Geology ↔ relates to ↔ Mining Gems

The Mine Safety and Health Administration (MSHA) () is a small agency of the United States Department of Labor which administers the provisions of the Federal Mine Safety and Health Act of 1977 ("Mine Act") to enforce compliance with mandatory safety and health standards as a means to eliminate fatal accidents, to reduce the frequency and severity of nonfatal accidents, to minimize health hazards, and to promote improved safety and health conditions in the nation's mines. MSHA carries out the mandates of the Mine Act at all mining and mineral processing operations in the United States, regardless of size, number of employees, commodity mined, or method of extraction. David Zatezalo was sworn in as Assistant Secretary of Labor for Mine Safety and Health, and head of MSHA, on November 30, 2017. He served until January 20, 2021. Jeannette Galanais served as Acting Assistant Secretary by President Joe Biden on February 1, 2021 until Christopher Williamson took office on April 11, 2022. MSHA is organized into several divisions. The Coal Mine Safety and Health division is divided into 12 districts covering coal mining in different portions of the United States.

uce the frequency and severity of nonfatal accidents, to minimize health hazards, and to promote improved safety and health conditions in the nation's mines. MSHA carries out the mandates of the Mine Act at all mining and mineral processing operations in the United States, regardless of size, number of employees, commodity mined, or method of extraction. David Zatezalo was sworn in as Assistant Secretary of Labor for Mine Safety and Health, and head of MSHA, on November 30, 2017. He served until January 20, 2021. Jeannette Galanais served as Acting Assistant Secretary by President Joe Biden on February 1, 2021 until Christopher Williamson took office on April 11, 2022. MSHA is organized into several divisions. The Coal Mine Safety and Health division is divided into 12 districts covering coal mining in different portions of the United States.

s mines. MSHA carries out the mandates of the Mine Act at all mining and mineral processing operations in the United States, regardless of size, number of employees, commodity mined, or method of extraction. David Zatezalo was sworn in as Assistant Secretary of Labor for Mine Safety and Health, and head of MSHA, on November 30, 2017. He served until January 20, 2021. Jeannette Galanais served as Acting Assistant Secretary by President Joe Biden on February 1, 2021 until Christopher Williamson took office on April 11, 2022. MSHA is organized into several divisions. The Coal Mine Safety and Health division is divided into 12 districts covering coal mining in different portions of the United States.

tment of Environmental Quality is the department of the Idaho state government responsible for administering state and federal environmental laws and regulations. The department's main offices are in Boise, and six regional offices are also maintained. History The department was established in 2000 upon the passing of amendments to the Idaho Environmental Protection and Health Act.

also maintained. History The department was established in 2000 upon the passing of amendments to the Idaho Environmental Protection and Health Act. Before 2000, DEQ in Idaho was a division of the Department of Health and Welfare. Structure and functions It is organized into five divisions: Air Quality: responsible for monitoring air pollution and permits relating to the same Water Quality: sets water quality standards and monitors ground, surface, and drinking water quality Waste Management and Remediation: responsible for all issues relating to waste disposal Environmental Management and Information: provides technical communications services, including publications Technical Services: the research and technical enforcement division, including inspection activities The department also exercises non-regulatory oversight of the Idaho National Laboratory. The director of the department reports to the governor.

Air Quality: responsible for monitoring air pollution and permits relating to the same Water Quality: sets water quality standards and monitors ground, surface, and drinking water quality Waste Management and Remediation: responsible for all issues relating to waste disposal Environmental Management and Information: provides technical communications services, including publications Technical Services: the research and technical enforcement division, including inspection activities The department also exercises non-regulatory oversight of the Idaho National Laboratory. The director of the department reports to the governor.

niversity comprises ten undergraduate, graduate, and professional schools. It enrolls approximately 12,000 students across its campuses, with 11,000 on the Moscow campus. The university is classified among "R1: Very High Spending and Doctorate Production". Located on the rural Palouse, the university is represented in intercollegiate athletics by the Idaho Vandals, who compete in NCAA Division I, primarily in the Big Sky Conference.

Under the elms Rare Camperdown elms line the walkway between the Music building, Nichols Building (home to Family and Consumer Sciences) and Administration Building. These "upside-down" trees have been on campus for over 80 years and are among few of their kind in the Northwest. The weeping branches and knotty trunk are formed by being grafted upwards. Steam plant Built in 1926, the steam plant provides heat to U of I buildings from a single location. Originally designed to burn coal, then oil, then natural gas, the plant was modified in 1986 to burn waste wood chips left over from local sawmills. The use of wood has significantly reduced the emissions of the plant, as well as cut costs to heat the campus. The plant is shut down twice a year for cleaning and maintenance.

College of Agricultural and Life Sciences (CALS, renamed 2001, formerly Agriculture (1901)) College of Art and Architecture (1981) College of Business and Economics (CBE, 1925) College of Education, Health and Human Sciences (EHH S,1920) College of Engineering (1911) College of Graduate Studies (COGS) College of Law (1909) College of Letters, Arts, and Social Sciences (CLASS, 2002, formed after split of Letters and Science (1900)) College of Natural Resources (CNR, renamed 2000, formerly Forestry, Wildlife, & Range Sciences, originally Forestry (1917)) College of Science (2002, formed after split of Letters and Science, and dissolution of Mines and Earth Resources) School of Health and Medical Professions (SHAMP, 2024) In July 2002, the College of Letters & Science was split into two separate colleges: the College of Science and the College of Letters, Arts, and Social Sciences (CLASS). Concurrently, the College of Mines and Earth Resources was discontinued; its programs were split between the College of Engineering and the new College of Science. The College of Law opened a second campus in Boise in 2010. Initially, the Boise campus only offered third-year classes. It expanded to offer second-year classes in 2014, and as of 2017–18, law students can take their entire three-year curriculum at either location. For the 2024–2025 academic year, the middle 50% of enrolled students scored between 1030 and 1330 on the SAT (with a 50th percentile of 1180), between 510 and 670 on the SAT Evidence-Based Reading and Writing section (50th percentile: 590), and between 520 and 660 on the SAT Math section (50th percentile: 590). Reputation and rankings U.S. News & World Report ranks U of I tied for 89th among the nation's best public universities and tied for 179th among the best national universities in its 2020 report. In 2024, Washington Monthly ranked U of I 83rd among 438 national universities in the U.S. based on U of I's contribution to the public good, as measured by social mobility, research, and promoting public service. In 2025, the Carnegie Classification listed University of Idaho among "R1 Doctoral Universities – Very high research spending and doctorate production", among with other 186 universities. The University of Idaho is included in the 2021 edition of Princeton Review's "Best 386 Colleges." The Princeton Review also ranks U-Idaho as one of the nation's top 286 environmentally responsible colleges. The university was named by the Corporation for National and Community Service to the 2010 President's Higher Education Community Service Honor Roll for exemplary service efforts—more than 3,800 students volunteered more than 150,000 hours to community and service-learning.

ds to undergo enrichment so that enough uranium-235 is present. Uranium-238 is fissionable by fast neutrons and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope, uranium-233, can be produced from natural thorium and is studied for future industrial use in nuclear technology. Uranium-238 has a small probability for spontaneous fission or even induced fission with fast neutrons; uranium-235, and to a lesser degree uranium-233, have a much higher fission cross-section for slow neutrons. In sufficient concentration, these isotopes maintain a sustained nuclear chain reaction. This generates the heat in nuclear power reactors and produces the fissile material for nuclear weapons. The primary civilian use for uranium harnesses the heat energy to produce electricity. Depleted uranium (238U) is used in kinetic energy penetrators and armor plating. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, who named the new element after the recently discovered planet Uranus. Eugène-Melchior Péligot was the first person to isolate the metal, and its radioactive properties were discovered in 1896 by Henri Becquerel. Research by Otto Hahn, Lise Meitner, Enrico Fermi and others, such as J. Robert Oppenheimer starting in 1934 led to its use as a fuel in the nuclear power industry and in Little Boy, the first nuclear weapon used in war. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of nuclear weapons that used uranium metal and uranium-derived plutonium-239. Dismantling of these weapons and related nuclear facilities is carried out within various nuclear disarmament programs and costs billions of dollars. Weapon-grade uranium obtained from nuclear weapons is diluted with uranium-238 and reused as fuel for nuclear reactors.

A team led by Enrico Fermi in 1934 found that bombarding uranium with neutrons produces beta rays (electrons or positrons from the elements produced; see beta particle). The fission products were at first mistaken for new elements with atomic numbers 93 and 94, which the Dean of the Sapienza University of Rome, Orso Mario Corbino, named ausenium and hesperium, respectively. The experiments leading to the discovery of uranium's ability to fission (break apart) into lighter elements and release binding energy were conducted by Otto Hahn and Fritz Strassmann in Hahn's laboratory in Berlin. Lise Meitner and her nephew, physicist Otto Robert Frisch, published the physical explanation in February 1939 and named the process "nuclear fission". Soon after, Fermi hypothesized that fission of uranium might release enough neutrons to sustain a fission reaction. Confirmation of this hypothesis came in 1939, and later work found that on average about 2.5 neutrons are released by each fission of uranium-235. Fermi urged Alfred O. C. Nier to separate uranium isotopes for determination of the fissile component, and on 29 February 1940, Nier used an instrument he built at the University of Minnesota to separate the world's first uranium-235 sample in the Tate Laboratory. Using Columbia University's cyclotron, John Dunning confirmed the sample to be the isolated fissile material on 1 March. Further work found that the far more common uranium-238 isotope can be transmuted into plutonium, which, like uranium-235, is also fissile by thermal neutrons. These discoveries led numerous countries to begin working on the development of nuclear weapons and nuclear power. Despite fission having been discovered in Germany, the Uranverein ("uranium club") Germany's wartime project to research nuclear power and/or weapons was hampered by limited resources, infighting, the exile or non-involvement of several prominent scientists in the field and several crucial mistakes such as failing to account for impurities in available graphite samples which made it appear less suitable as a neutron moderator than it is in reality. Germany's attempts to build a natural uranium / heavy water reactor had not come close to reaching criticality by the time the Americans reached Haigerloch, the site of the last German wartime reactor experiment. On 2 December 1942, as part of the Manhattan Project, another team led by Enrico Fermi was able to initiate the first artificial self-sustained nuclear chain reaction, Chicago Pile-1. An initial plan using enriched uranium-235 was abandoned as it was as yet unavailable in sufficient quantities.

The X-10 Graphite Reactor at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, formerly known as the Clinton Pile and X-10 Pile, was the world's second artificial nuclear reactor (after Enrico Fermi's Chicago Pile) and was the first reactor designed and built for continuous operation. Argonne National Laboratory's Experimental Breeder Reactor I, located at the Atomic Energy Commission's National Reactor Testing Station near Arco, Idaho, became the first nuclear reactor to create electricity on 20 December 1951. Initially, four 150-watt light bulbs were lit by the reactor, but improvements eventually enabled it to power the whole facility (later, the town of Arco became the first in the world to have all its electricity come from nuclear power generated by BORAX-III, another reactor designed and operated by Argonne National Laboratory). The world's first commercial scale nuclear power station, Obninsk in the Soviet Union, began generation with its reactor AM-1 on 27 June 1954. Other early nuclear power plants were Calder Hall in England, which began generation on 17 October 1956, and the Shippingport Atomic Power Station in Pennsylvania, which began on 26 May 1958.

t (BLM) is an agency within the United States Department of the Interior responsible for administering U.S. federal lands. Headquartered in Washington, D.C., the BLM oversees more than 247.3 million acres (1,001,000 km2) of land, or one-eighth of the United States's total landmass. The Bureau was created by Congress during the presidency of Harry S Truman in 1946 by combining two existing agencies: the United States General Land Office and the Grazing Service. The agency manages the federal government's nearly 700 million acres (2,800,000 km2) of subsurface mineral estate located beneath federal, state and private lands severed from their surface rights by the Homestead Act of 1862. Most BLM public lands are located in these 12 western states: Alaska, Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. The mission of the BLM is "to sustain the health, diversity, and productivity of the public lands for the use and enjoyment of present and future generations." Originally BLM holdings were described as "land nobody wanted" because homesteaders had passed them by. All the same, ranchers hold nearly 18,000 permits and leases for livestock grazing on 155 million acres (630,000 km2) of BLM public lands. The agency manages 263 wilderness areas, 31 national monuments and some 710 other protected areas as part of the National Conservation Lands (formerly known as the National Landscape Conservation System), totaling about 39.5 million acres (160,000 km2). In addition the National Conservation Lands include nearly 2,700 miles of Wild and Scenic Rivers, and nearly 6,000 miles of National Scenic and Historic Trails. There are more than 63,000 oil and gas wells on BLM public lands.

presidency of Harry S Truman in 1946 by combining two existing agencies: the United States General Land Office and the Grazing Service. The agency manages the federal government's nearly 700 million acres (2,800,000 km2) of subsurface mineral estate located beneath federal, state and private lands severed from their surface rights by the Homestead Act of 1862. Most BLM public lands are located in these 12 western states: Alaska, Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. The mission of the BLM is "to sustain the health, diversity, and productivity of the public lands for the use and enjoyment of present and future generations." Originally BLM holdings were described as "land nobody wanted" because homesteaders had passed them by. All the same, ranchers hold nearly 18,000 permits and leases for livestock grazing on 155 million acres (630,000 km2) of BLM public lands. The agency manages 263 wilderness areas, 31 national monuments and some 710 other protected areas as part of the National Conservation Lands (formerly known as the National Landscape Conservation System), totaling about 39.5 million acres (160,000 km2). In addition the National Conservation Lands include nearly 2,700 miles of Wild and Scenic Rivers, and nearly 6,000 miles of National Scenic and Historic Trails. There are more than 63,000 oil and gas wells on BLM public lands.

iginally BLM holdings were described as "land nobody wanted" because homesteaders had passed them by. All the same, ranchers hold nearly 18,000 permits and leases for livestock grazing on 155 million acres (630,000 km2) of BLM public lands. The agency manages 263 wilderness areas, 31 national monuments and some 710 other protected areas as part of the National Conservation Lands (formerly known as the National Landscape Conservation System), totaling about 39.5 million acres (160,000 km2). In addition the National Conservation Lands include nearly 2,700 miles of Wild and Scenic Rivers, and nearly 6,000 miles of National Scenic and Historic Trails. There are more than 63,000 oil and gas wells on BLM public lands.

erred to as the Silver City Range. About 8.3 kilometres (5.2 mi) west of Silver City is the De Lamar ghost town in Jordan Creek below the mine workings on De Lamar Mountain to the south. The area was active in the late 1880s.

The Owyhee Mountains are a mountain range in Owyhee County, Idaho and Malheur County, Oregon. Mahogany Mountain and the associated volcanic craters of the Lake Owyhee volcanic field are in the Owyhee Mountains of Oregon just east of the Owyhee Reservoir on the Owyhee River. The southeastern end of the range including the old mining area west of Silver City is referred to as the Silver City Range. About 8.3 kilometres (5.2 mi) west of Silver City is the De Lamar ghost town in Jordan Creek below the mine workings on De Lamar Mountain to the south. The area was active in the late 1880s.

ilometres (5.2 mi) west of Silver City is the De Lamar ghost town in Jordan Creek below the mine workings on De Lamar Mountain to the south. The area was active in the late 1880s.

phold the integrity of the aquifer, and to prevent contaminants from reaching the groundwater. Controversy arises in the use of groundwater when its usage impacts surface water systems, or when human activity threatens the integrity of the local aquifer system. Introduction Hydrogeology is an interdisciplinary subject; it can be difficult to account fully for the chemical, physical, biological, and even legal interactions between soil, water, nature, and society. The study of the interaction between groundwater movement and geology can be quite complex. Groundwater does not always follow the surface topography; groundwater follows pressure gradients (flow from high pressure to low), often through fractures and conduits in circuitous paths. Taking into account the interplay of the different facets of a multi-component system often requires knowledge in several diverse fields at both the experimental and theoretical levels.

California California sees some of the largest controversies in groundwater usage due to the dry conditions California faces, high population, and intensive agriculture. Conflicts generally occur over pumping groundwater and shipping it out of the area, unfair use of water by a commercial company, and contamination of groundwater by development projects. In Siskiyou County in northern California, the California Superior Court ruled poor groundwater regulations have allowed pumping to diminish the flows in the Scott River and disturbed the natural habitat of salmon. In Owens Valley in central California, groundwater was pumped for use in fish farms, which resulted in the death of local meadows and other ecosystems. This resulted in a lawsuit and settlement against the fish companies. Development in southern California is threatening local aquifers, contaminating groundwater through construction and normal human activity. For example, a solar project in San Bernardino County would allegedly threaten the ecosystem of bird and wildlife species because of its use of up to 1.3 million cubic meters of groundwater, which could impact Harper Lake.

Colorado Due to its arid climate, the state of Colorado gets most of its water from underground. Because of this, there have been issues regarding groundwater engineering practices. As many as 65,000 people were affected when high levels of PFCs were found in the Widefield Aquifer. Groundwater use in Colorado dates back to before the 20th century. Nineteen of Colorado's 63 counties depend mostly on groundwater for supplies and domestic uses. The Colorado Geological Survey has three significant reports on groundwater in the Denver Basin. The first report Geology of Upper Cretaceous, Paleocene and Eocene Strata in the Southwestern Denver Basin, The second report Bedrock Geology, Structure, and Isopach Maps of the Upper Cretaceous to Paleogene Strata between Greeley and Colorado Springs, The third publication Cross Sections of the Freshwater Bearing Strata of the Denver Basin between Greeley and Colorado Springs. New trends in groundwater engineering/hydrogeology Since the first wells were made thousands of years ago, groundwater systems have been changed by human activity. 50 years ago, the sustainability of these systems on a larger scale began to come into consideration, becoming one of the main focuses of groundwater engineering.

sumed on a large scale (1.3 million metric tons per year in 2022) for uses in many critical industries including refractories (50%), lithium-ion batteries (18%), foundries (10%), and lubricants (5%), among others (17%). Graphite converts to diamond under extremely high pressure and temperature.

Research Research and development efforts continue into new methods for the industrial production of graphite for a variety of applications, including lithium-ion batteries, refractories, and foundries, among others. Significant work has been done on graphitizing of traditionally non-graphitizable carbons. A company in New Zealand utilizes forestry waste to produce what they have termed 'biographite' through a process referred to as thermo-catalytic graphitization.

The ability to leave marks on paper and other objects gave graphite its name, given in 1789 by German mineralogist Abraham Gottlob Werner. It stems from γράφειν ("graphein"), meaning to write or draw in Ancient Greek. From the 16th century, all pencils were made with leads of English natural graphite, but modern pencil lead is most commonly a mix of powdered graphite and clay; it was invented by Nicolas-Jacques Conté in 1795. It is chemically unrelated to the metal lead, whose ores had a similar appearance, hence the continuation of the name. Plumbago is another older term for natural graphite used for drawing, typically as a lump of the mineral without a wood casing. The term plumbago drawing is normally restricted to 17th and 18th-century works, mostly portraits. Today, pencils are still a small but significant market for natural graphite. Around 7% of the 1.1 million tonnes produced in 2011 was used to make pencils. Low-quality amorphous graphite is used and sourced mainly from China. In art, graphite is typically used to create detailed and precise drawings, as it allows for a wide range of values (light to dark) to be achieved. It can also be used to create softer, more subtle lines and shading. Graphite is popular among artists because it is easy to control, easy to erase, and produces a clean, professional look. It is also relatively inexpensive and widely available. Many artists use graphite in conjunction with other media, such as charcoal or ink, to create a range of effects and textures in their work.

ider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or even water. Mining is also associated with a range of environmental, health, and social impacts. Mining activities contribute to land degradation, water contamination, and habitat loss. In addition to environmental impacts, mining has been linked to occupational health risks and community displacement, and has affected low-income and marginalized populations. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials, and final reclamation or restoration of the land after the mine is closed. Mining materials are often obtained from ore bodies, lodes, veins, seams, reefs, or placer deposits. The exploitation of these deposits for raw materials is dependent on investment, labor, energy, refining, and transportation costs. Mining operations can have negative environmental impacts, both during mining and after the mine closes. Hence, most of the world's nations have enacted regulations to reduce the impact; however, the outsized role of mining in generating business for often rural, remote, or economically depressed communities means that governments frequently fail to enforce them fully. Work safety has long been a concern as well, and where enforced, modern practices have significantly improved safety in mines. Unregulated, poorly regulated or illegal mining, especially in developing economies, frequently contributes to local human rights violations and environmental conflicts.

While individual entrepreneurs or small businesses can conduct exploration and mining, most modern-day mines are large enterprises that require substantial capital to establish. Consequently, the mining sector of the industry is dominated by large, often multinational companies, most of which are publicly listed. It can be argued that what is referred to as the 'mining industry' comprises two sectors: one specializing in the exploration of new resources and the other in mining those resources. The exploration sector is typically made up of individuals and small mineral resource companies, called "juniors", that depend on venture capital. The mining sector comprises large multinational companies that are sustained by production from their operations. Various other industries, such as equipment manufacturing, environmental testing, and metallurgical analysis, rely on and support the mining industry worldwide. Canadian stock exchanges have a particular focus on mining companies, particularly junior exploration companies, through Toronto's TSX Venture Exchange; Canadian companies raise capital on these exchanges and then invest the money in exploration globally. Some have argued that below juniors, there exists a substantial sector of illegitimate companies primarily focused on manipulating stock prices. Mining operations can be grouped into five major categories based on the resources they exploit. These are oil and gas extraction, coal mining, metal ore mining, nonmetallic mineral mining and quarrying, and mining support activities. Of all of these categories, oil and gas extraction remains one of the largest in terms of its global economic importance. Prospecting potential mining sites, a vital area of concern for the mining industry, is now done using sophisticated new technologies such as seismic prospecting and remote-sensing satellites. Mining is heavily affected by the prices of the commodity minerals, which are often volatile. The 2000s commodities boom ("commodities supercycle") increased commodity prices, driving aggressive mining.

Safety has long been a concern in the mining business, especially in sub-surface mining. The Courrières mine disaster, Europe's worst mining accident, involved the death of 1,099 miners in Northern France on March 10, 1906. This disaster was surpassed only by the Benxihu Colliery accident in China on April 26, 1942, which killed 1,549 miners. Although mining has become substantially safer than it was in previous decades, mining accidents still occur. Government figures indicate that around 5,000 Chinese miners die in accidents each year, while other reports have suggested a figure as high as 20,000. Between 1870 and 1920 in Queensland, Australia, an increase in mining accidents led to more safety measures regarding the use of explosives in mining. In the Democratic Republic of the Congo (DRC), safety concerns have been raised for both those who work in the mines and those who live in the surrounding areas. Workers are usually seen with a mustard-colored powder that turned out to be "...dried sulfuric acid, [which] they use in the mine to process the [mineral] ores. Surrounding the mine, there is a "small stream of foul, sludgy water that passes beneath a bridge next to the fence." Around the mine, biomonitoring studies of metal exposure show that "The levels found in Kinshasa remain above the CDC reference value (>5 μg/dL) and constitute a public health concern," and that subjects living close (< 3 km) to mines or metal-processing industries have higher urinary concentrations of various metals (p < 0.01) than those living further away (3–10 km)," revealing an "... absence of a national policy to control and prevent exposure to harmful chemicals." In the mines, specifically at the Tenke Fungurume mine, there were hundreds of thousands of people [who] engaged in the feverish excavation of cobalt in medieval conditions." These workers were locals who worked for "two dollars (roughly one day's income)." In addition, the rates of schistosomiasis, a mining related disease endemic to DRC, were found to be "higher among mining workers (27%) than in the total population (<13 %)," indicating harmful long-term impacts for the workers. In South Africa, issues are similar to those in the DRC. Miners are exposed to silica dust, which "increases the risk of pulmonary tuberculosis," with a tuberculosis rate of "over 1,000 per 100,000." "Mine shafts themselves are crowded and poorly-ventilated, but so are hostels where over a dozen men can share a small room. These conditions are highly conducive to infection; the rate of recurrent tuberculosis in a recent South African prospective cohort of 600 miners was about 8 per 100 person-years," which increases the risk of tuberculosis spreading in both mining and living locations. Past the mines, the "extraction of minerals often leads to the disruption of ecosystems, polluting water sources, and degrading habitats including cultural heritage critical for the livelihoods of people." Mining accidents continue worldwide, including incidents that have caused dozens of fatalities at a time, such as the 2007 Ulyanovskaya Mine disaster in Russia, the 2009 Heilongjiang mine explosion in China, and the 2010 Upper Big Branch Mine disaster in the United States. Mining has been identified by the National Institute for Occupational Safety and Health (NIOSH) as a priority industry sector in the National Occupational Research Agenda (NORA) to identify and provide intervention strategies regarding occupational health and safety issues. The Mining Safety and Health Administration (MSHA) was established in 1978 to "work to prevent death, illness, and injury from mining and promote safe and healthful workplaces for US miners." Since its implementation in 1978, the number of miner fatalities has decreased from 242 miners in 1978 to 24 miners in 2019. There are numerous occupational hazards associated with mining, including exposure to rockdust, which can lead to diseases such as silicosis, asbestosis, and pneumoconiosis. Gases in the mine can lead to asphyxiation and have a risk of ignition. Mining equipment can generate considerable noise, putting workers at risk for hearing loss. Cave-ins, rock falls, and exposure to excess heat are also known hazards. The NIOSH Recommended Exposure Limit (REL) of noise is 85 dBA with a 3 dBA exchange rate, and the MSHA Permissible Exposure Limit (PEL) is 90 dBA with a 5 dBA exchange rate as an 8-hour time-weighted average. NIOSH has found that 25% of noise-exposed workers in Mining, Quarrying, and Oil and Gas Extraction have hearing impairment. The prevalence of hearing loss increased by 1% from 1991 to 2001 within these workers. Noise studies have been conducted in several mining environments. Stageloaders (84-102 dBA), shearers (85-99 dBA), auxiliary fans (84–120 dBA), continuous mining machines (78–109 dBA), and roof bolters (92–103 dBA) represent some of the noisiest equipment in underground coal mines. Dragline oilers, dozer operators, and welders using air arcing were occupations with the highest noise exposures among surface coal miners. Coal mines had the highest hearing loss injury likelihood. Environmental effects Mining activities can significantly contribute to water pollution through the release of heavy metals and toxic substances into surrounding waterways. Processes such as acid mine drainage occur when sulfide minerals are exposed to air and water, producing acidic runoff that carry contaminants such as arsenic, lead, and mercury into rivers and groundwater. This pollution can harm aquatic ecosystems, reduce water quality, and pose risks to human health, particularly in communities that rely on local water sources for drinking and agriculture. In some cases, contamination persists long after mining operations have stopped, making remediation difficult and costly. Water pollution from mining can also result from the storage and disposal of mine waste, including tailings and waste rock, which may contain hazardous chemicals and heavy metals. Failures or leaks in tailings storage facilities have released large volumes of contaminated materials into rivers and surrounding ecosystems, causing widespread environmental damage. Even without major failures, runoff from mining sites can transport pollutants into nearby waterways during rainfall events, further degrading water quality. Abandoned mine sites are a particularly significant source of ongoing contamination, as untreated drainage can continue to release acidic and metal laden water into the environment for decades after closure. This is important because water is vital for many communities' survival. Fresh rivers are a source of fish and fresh water. However, the water isn't fresh anymore, it is heavily polluted by toxic runoff from nearby mines. Researcher Siddharth Kara explains that in the context of cobalt mining in the Democratic Republic of Congo, "water is heavily polluted, a condition that local residents attribute to toxic runoff from nearby mines. The environmental researcher at the University of Lubumbashi whom I met after my visit to Kipushi, Germain, took samples from the river water near Mupanja and found particularly high levels of lead, chromium, cobalt, and industrial acids.

y used for precious metal deposits (particularly gold, and platinum to a much lesser extent) and gemstones, both of which are often found in alluvial deposits—deposits of sand and gravel in modern or ancient stream beds, or occasionally glacial deposits. The metal or gemstones, having been moved by stream flow from an original source such as a vein, are typically only a minuscule portion of the total deposit. Since gems and heavy metals like gold are considerably denser than sand, they tend to accumulate at the base of placer deposits. Placer deposits can be as young as a few years old, such as the Canadian Queen Charlotte beach gold placer deposits, or billions of years old like the Elliot Lake uranium paleoplacer within the Huronian Supergroup in Canada. The containing material in an alluvial placer mine may be too loose to safely mine by tunnelling, though it is possible where the ground is permanently frozen.

An alternative etymology derives the English word from American Spanish placer (placer, sandbank), from earlier placel, apparently from obsolete Portuguese placel (placer, sandbank). History Placers supplied most of the gold for a large part of the ancient world. Hydraulic mining methods such as hushing were used widely by the Romans across their empire, but especially in the gold fields of northern Spain after its conquest by Augustus in 25 BC.

an original source such as a vein, are typically only a minuscule portion of the total deposit. Since gems and heavy metals like gold are considerably denser than sand, they tend to accumulate at the base of placer deposits. Placer deposits can be as young as a few years old, such as the Canadian Queen Charlotte beach gold placer deposits, or billions of years old like the Elliot Lake uranium paleoplacer within the Huronian Supergroup in Canada. The containing material in an alluvial placer mine may be too loose to safely mine by tunnelling, though it is possible where the ground is permanently frozen.

eyond currency and investment uses such as coins and bullion, silver is an important industrial material. It is used in photovoltaics, electrical contacts and conductors, printed electronics, brazing alloys, catalysis, specialised mirrors and window coatings, and antimicrobial materials.

Silver is similar in its physical and chemical properties to its two vertical neighbours in group 11 of the periodic table: copper, and gold. Its 47 electrons are arranged in the configuration [Kr]4d105s1, similarly to copper ([Ar]3d104s1) and gold ([Xe]4f145d106s1); group 11 is one of the few groups in the d-block which has a completely consistent set of electron configurations. This distinctive electron configuration, with a single electron in the highest occupied s subshell over a filled d subshell, accounts for many of the singular properties of metallic silver. Silver is a relatively soft and extremely ductile and malleable transition metal, though it is slightly less malleable than gold. Silver crystallises in a face-centred cubic lattice with bulk coordination number 12, where only the single 5s electron is delocalised, similarly to copper and gold. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant, white, metallic lustre that can take a high polish, and which is so characteristic that the name of the metal itself has become a colour name. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm. At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm. Very high electrical and thermal conductivity are common to the elements in group 11, because their single s electron is free and does not interact with the filled d subshell, as such interactions (which occur in the preceding transition metals) lower electron mobility. The thermal conductivity of silver is among the highest of all materials, although the thermal conductivity of carbon (in the diamond allotrope) and superfluid helium-4 are higher. The electrical conductivity of silver is the highest of all metals, greater even than copper. Silver also has the lowest contact resistance of any metal. Silver is rarely used for its electrical conductivity, due to its high cost, although an exception is in radio-frequency engineering, particularly at VHF and higher frequencies where silver plating improves electrical conductivity because those currents tend to flow on the surface of conductors rather than through the interior. During World War II in the US, 13540 tons of silver were used for the electromagnets in calutrons for enriching uranium, mainly because of the wartime shortage of copper. Silver readily forms alloys with copper, gold, and zinc. Zinc-silver alloys with low zinc concentration may be considered as face-centred cubic solid solutions of zinc in silver, as the structure of the silver is largely unchanged while the electron concentration rises as more zinc is added.

Silver is a rather unreactive metal. This is because its filled 4d shell is not very effective in shielding the electrostatic forces of attraction from the nucleus to the outermost 5s electron, and hence silver is near the bottom of the electrochemical series (E0(Ag+/Ag) = +0.799 V). In group 11, silver has the lowest first ionisation energy (showing the instability of the 5s orbital), but has higher second and third ionisation energies than copper and gold (showing the stability of the 4d orbitals), so that the chemistry of silver is predominantly that of the +1 oxidation state, reflecting the increasingly limited range of oxidation states along the transition series as the d-orbitals fill and stabilise. Unlike copper, for which the larger hydration energy of Cu2+ as compared to Cu+ is the reason why the former is the more stable in aqueous solution and solids despite lacking the stable filled d-subshell of the latter, with silver this effect is swamped by its larger second ionisation energy. Hence, Ag+ is the stable species in aqueous solution and solids, with Ag2+ being much less stable as it oxidises water. Most silver compounds have significant covalent character due to the small size and high first ionisation energy (730.8 kJ/mol) of silver. Furthermore, silver's Pauling electronegativity of 1.93 is higher than that of lead (1.87), and its electron affinity of 125.6 kJ/mol is much higher than that of hydrogen (72.8 kJ/mol) and not much less than that of oxygen (141.0 kJ/mol). Due to its full d-subshell, silver in its main +1 oxidation state exhibits relatively few properties of the transition metals proper from groups 4 to 10, forming rather unstable organometallic compounds, forming linear complexes showing very low coordination numbers like 2, and forming an amphoteric oxide as well as Zintl phases like the post-transition metals. Unlike the preceding transition metals, the +1 oxidation state of silver is stable even in the absence of π-acceptor ligands. Silver does not react with air, even at red heat, and thus was considered by alchemists to be a noble metal. Its reactivity is intermediate between that of copper (which forms copper(I) oxide when heated in air to red heat) and gold. Like copper, silver reacts with sulfur and its compounds; in their presence, silver tarnishes in air to form the black silver sulfide (copper forms the green sulfate instead, while gold does not react). While silver is not attacked by non-oxidising acids, the metal dissolves readily in hot concentrated sulfuric acid, as well as dilute or concentrated nitric acid. In the presence of air, and especially in the presence of hydrogen peroxide, silver dissolves readily in aqueous solutions of cyanide. The three main forms of deterioration in historical silver artifacts are tarnishing, formation of silver chloride due to long-term immersion in salt water, as well as reaction with nitrate ions or oxygen. Fresh silver chloride is pale yellow, becoming purplish on exposure to light; it projects slightly from the surface of the artifact or coin. The precipitation of copper in ancient silver can be used to date artifacts, as copper is nearly always a constituent of silver alloys. Silver metal is attacked by strong oxidant such as potassium permanganate (KMnO4) and potassium dichromate (K2Cr2O7), and in the presence of potassium bromide (KBr). These compounds are used in photography to bleach silver images, converting them to silver bromide that can either be fixed with thiosulfate or redeveloped to intensify the original image. Silver forms cyanide complexes (silver cyanide) that are soluble in water in the presence of an excess of cyanide ions. Silver cyanide solutions are used in electroplating of silver. The common oxidation states of silver are (in order of commonness): +1 (the most stable state; for example, silver nitrate, AgNO3); +2 (highly oxidising; for example, silver(II) fluoride, AgF2); and even very rarely +3 (extreme oxidising; for example, potassium tetrafluoroargentate(III), KAgF4). The +3 state requires very strong oxidising agents to attain, such as fluorine or peroxodisulfate, and some silver(III) compounds react with atmospheric moisture and attack glass.

n of industrial and municipal resources. In the United States, mine reclamation is a regular part of modern mining practices. Modern mine reclamation reduces the environmental effects of mining. Many abandoned mine sites have no reclamation works undertaken. The majority of mines throughout history have no stringent regulations applied. As a practice, mine reclamation began at the start of the 20th century. Returning the landscape to its original state is not possible in all cases.

Under the Surface Mining Control and Reclamation Act of 1977 The Surface Mining Control and Reclamation Act of 1977 (SMCRA) is the primary federal law that regulates the environmental effects of coal mining in the United States. It established permitting guidelines for existing and future coal mines as well as a trust fund to finance the reclamation of abandoned mines. SMCRA balances the need to protect the environment from the effects of surface coal mining with the Nation's need for coal as an essential energy source. It ensures that coal mining operations are conducted in an environmentally responsible manner and that the land is adequately reclaimed during and following the mining process. Most coal-mining states now have the primary responsibility to regulate surface coal mining on lands within their jurisdiction, with the Office of Surface Mining Reclamation and Enforcement (OSMRE) performing an oversight role. Under SMCRA, prior to receiving a mining permit, operators must present a detailed and comprehensive plan for reclaiming the land after mining has been completed. The reclamation plan must include, among other criteria, the pre-mining condition and use of the land to be mined; the proposed use of the land after reclamation; an estimated time table for the reclamation; and the steps that will be taken to comply with the relevant air and water quality laws. In addition to providing the reclamation plan, operators must also post a performance bond to ensure that monies will be available to complete the reclamation if the operator goes out of business prior to finishing the reclamation or is otherwise unable to complete the reclamation. The amount of the bond must equal the amount of the proposed reclamation plan.

Abandoned Mine Lands Program Funding for the reclamation of abandoned mines is accomplished through a coal production tax. Mine operators must pay a tax of $0.12 per ton for underground mined coal and $0.28 per ton for surfaced mined coal; the proceeds from this tax are put into the Abandoned Mine Reclamation Fund (created by SMCRA) to pay for the reclamation of abandoned mines. A percentage of the fund is distributed to states with approved reclamation programs for their projects, and the remaining monies are used by the federal government through the OSMRE to reclaim abandoned mines in states without active programs.

ndard conditions, when uncombined), making it difficult to work into metal. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw. Tungsten occurs in many alloys, which have numerous applications, including incandescent light bulb filaments, X-ray tubes, electrodes in gas tungsten arc welding, superalloys, and radiation shielding. Tungsten's hardness and high density make it suitable for military applications in penetrating projectiles. Tungsten compounds are often used as industrial catalysts. Its largest use is in tungsten carbide, a wear-resistant material used in metalworking, mining, and construction. About 50% of tungsten is used in tungsten carbide, with the remaining major use being alloys and steels: less than 10% is used in other compounds. Tungsten is the only metal in the third transition series that is known to occur in biomolecules, found in a few species of bacteria and archaea.

Its largest use is in tungsten carbide, a wear-resistant material used in metalworking, mining, and construction. About 50% of tungsten is used in tungsten carbide, with the remaining major use being alloys and steels: less than 10% is used in other compounds. Tungsten is the only metal in the third transition series that is known to occur in biomolecules, found in a few species of bacteria and archaea.

In its raw form, tungsten is a hard steel-grey metal that is often brittle and hard to work. Purified, monocrystalline tungsten retains its hardness (which exceeds that of many steels), and becomes malleable enough that it can be worked easily. It can be worked by forging, drawing, rolling, or extruding. Most materials based on tungsten are formed by sintering tungsten powder along with additives, though this results in a more porous final product. Of all metals in pure form, tungsten has the highest melting point (3,422 °C, 6,192 °F), lowest vapor pressure (at temperatures above 1,650 °C, 3,000 °F), and the highest tensile strength. Although carbon remains solid at higher temperatures than tungsten, carbon sublimes at atmospheric pressure instead of melting, so it has no melting point. Moreover, tungsten's most stable crystal phase does not exhibit any high-pressure-induced structural transformations for pressures up to at least 364 gigapascals. Tungsten has the lowest coefficient of thermal expansion of any pure metal. The low thermal expansion and high melting point and tensile strength of tungsten originate from strong covalent bonds formed between tungsten atoms by the 5d electrons. Alloying small quantities of tungsten with steel greatly increases its toughness. Tungsten exists in two major crystalline forms: α and β. The former has a body-centered cubic structure and is the more stable form. The structure of the β phase is called A15 cubic; it is metastable, but can coexist with the α phase at ambient conditions owing to non-equilibrium synthesis or stabilization by impurities. Contrary to the α phase which crystallizes in isometric grains, the β form exhibits a columnar habit. The α phase has one third of the electrical resistivity and a much lower superconducting transition temperature TC relative to the β phase: ca. 0.015 K vs. 1–4 K; mixing the two phases allows obtaining intermediate TC values. The TC value can also be raised by alloying tungsten with another metal (e.g. 7.9 K for W-Tc). Such tungsten alloys are sometimes used in low-temperature superconducting circuits. Isotopes Naturally occurring tungsten consists of four stable isotopes (182W, 183W, 184W, and 186W) and one very long-lived radioisotope, 180W. Theoretically, all five can decay into isotopes of element 72 (hafnium) by alpha emission, but only 180W has been observed to do so, with a half-life of (1.8±0.2)×1018 years; on average, this yields about two alpha decays of 180W per gram of natural tungsten per year. Another 34 artificial radioisotopes of tungsten have been characterized, the most stable of which are 181W with a half-life of 121.2 days, 185W with a half-life of 75.1 days, 188W with a half-life of 69.4 days, 178W with a half-life of 21.6 days, and 187W with a half-life of 23.72 h. All of the remaining radioactive isotopes have half-lives of less than 3 hours, and most of these have half-lives below 8 minutes.

used for economic and industrial purposes. These materials include precious and base metals, nonmetallic minerals and construction-grade stone. Economic geology is a subdiscipline of the geosciences; according to Lindgren (1933) it is “the application of geology”. It may be called the scientific study of the Earth's sources of mineral raw materials and the practical application of the acquired knowledge. The study is primarily focused on metallic mineral deposits and mineral resources. The techniques employed by other Earth science disciplines (such as geochemistry, mineralogy, geophysics, petrology, paleontology and structural geology) might all be used to understand, describe and exploit an ore deposit. Economic geology is studied and practiced by geologists.

discipline of the geosciences; according to Lindgren (1933) it is “the application of geology”. It may be called the scientific study of the Earth's sources of mineral raw materials and the practical application of the acquired knowledge. The study is primarily focused on metallic mineral deposits and mineral resources. The techniques employed by other Earth science disciplines (such as geochemistry, mineralogy, geophysics, petrology, paleontology and structural geology) might all be used to understand, describe and exploit an ore deposit. Economic geology is studied and practiced by geologists.

employed by other Earth science disciplines (such as geochemistry, mineralogy, geophysics, petrology, paleontology and structural geology) might all be used to understand, describe and exploit an ore deposit. Economic geology is studied and practiced by geologists.

, coined the name "Treasure Valley" in 1959 to reflect the treasure chest of resources and opportunities that the region offered. The valley has a very diverse terrain, from sage flatlands, to mesas, agricultural areas, and urbanized areas. As the Boise Metropolitan Area grows, more and more undeveloped and agricultural land is being urbanized. History Settling the region The tribes that roamed the area, specifically, were the Northern Paiute and Shoshone. In 1834, Thomas McKay built the original Fort Boise, in the area near present-day Parma, which was run for a time by Francois Payette. It later was moved because of flooding troubles and was abandoned in 1854. The Oregon Trail runs through the Treasure Valley. The valley was settled for the most part by ranchers and farmers, initially to supply the gold and silver mining communities in the higher elevations nearby: Idaho City in the Boise Basin and Silver City in the Owyhees. A new Fort Boise was constructed by the U.S. Army in 1863 in present-day Boise, from which the city grew.

ern Oregon to Boise, and is the most populated area in Idaho. Historically, the valley had been known as the Lower Snake River Valley or the Boise River Valley. Pete Olesen, president of the valley's association of local Chambers of Commerce, coined the name "Treasure Valley" in 1959 to reflect the treasure chest of resources and opportunities that the region offered. The valley has a very diverse terrain, from sage flatlands, to mesas, agricultural areas, and urbanized areas.

The Treasure Valley is a valley in the western United States, primarily in southwestern Idaho, where the Payette, Boise, Weiser, Malheur, and Owyhee rivers drain into the Snake River. It includes all the lowland areas from Vale in rural eastern Oregon to Boise, and is the most populated area in Idaho. Historically, the valley had been known as the Lower Snake River Valley or the Boise River Valley. Pete Olesen, president of the valley's association of local Chambers of Commerce, coined the name "Treasure Valley" in 1959 to reflect the treasure chest of resources and opportunities that the region offered. The valley has a very diverse terrain, from sage flatlands, to mesas, agricultural areas, and urbanized areas.

der the Idaho State Board of Land Commissioners and is the administrative arm of the Idaho Oil and Gas Conservation Commission. The Idaho Department of Lands staffs 16 offices and manages 2.5 million acres under a constitutional mandate on State Trust Lands to maximize long term returns.

Programs and responsibilities Different duties under the IDL include the forestry program, fire program, mining industry regulations, and the Idaho oil and gas conservation commission. Fire program The IDL works for the protection of more than 6 million acres of land. The IDL is responsible for the fire protection and conservation of state and private forest lands. The IDL also provides services for families to help cope with losses due to forest fire. The IDL works in coordination with two timber protective associations, U.S.

of mining practices, as well as administering forestry programs and providing fire protection and prevention on state lands. IDL operates under the Idaho State Board of Land Commissioners and is the administrative arm of the Idaho Oil and Gas Conservation Commission. The Idaho Department of Lands staffs 16 offices and manages 2.5 million acres under a constitutional mandate on State Trust Lands to maximize long term returns.

reference point. One of only four metal elements that is liquid at, or near, normal room temperature, gallium will melt in a person's hands at normal human body temperature of 37 °C (99 °F). Gallium alloys with low temperatures are used in thermometers as a non-toxic and environmentally friendly alternative to mercury, and can withstand higher temperatures than mercury. A melting point of −19 °C (−2 °F), well below the freezing point of water, is claimed for the alloy galinstan (62–⁠95% gallium, 5–⁠22% indium, and 0–⁠16% tin by weight), but that may be the freezing point with the effect of supercooling. Gallium is predominantly used in electronics. Gallium arsenide, the primary chemical compound of gallium in electronics, is used in microwave circuits, high-speed switching circuits, and infrared circuits. Semiconducting gallium nitride and indium gallium nitride produce blue and violet light-emitting diodes and diode lasers. Gallium is also used in the production of artificial gadolinium gallium garnet for jewelry. It has no known natural role in biology.

Physical properties Elemental gallium is not found in nature, but it is easily obtained by smelting. Very pure gallium is a silvery blue metal that fractures conchoidally like glass. Gallium forms alloys with most metals. It readily diffuses into cracks or grain boundaries of some metals such as aluminium, aluminium–zinc alloys and steel, causing extreme loss of strength and ductility called liquid metal embrittlement. Under normal conditions, gallium does not crystallize in any of the simple crystal structures. Instead, its stable phase (Ga-I) is a complex orthorhombic structure with eight atoms in the conventional unit cell. Within a unit cell, each atom has only one nearest neighbor (at a distance of 244 pm). The remaining six unit cell neighbors are spaced 27, 30 and 39 pm farther away, and they are grouped in pairs with the same distance. The bonding between the two nearest neighbors is covalent; hence Ga2 dimers are seen as the fundamental building blocks of the crystal. This explains the low melting point relative to the neighbor elements, aluminium and indium. This structure is strikingly similar to that of iodine and may form because of interactions between the single 4p electrons of gallium atoms, further away from the nucleus than the 4s electrons and the [Ar]3d10 core. This phenomenon recurs with mercury with its "pseudo-noble-gas" [Xe]4f145d106s2 electron configuration, which is liquid at room temperature. The 3d10 electrons do not shield the outer electrons very well from the nucleus and hence the first ionisation energy of gallium is greater than that of aluminium.

Mendeleev further predicted that eka-aluminium would be discovered by means of the spectroscope, and that metallic eka-aluminium would dissolve slowly in both acids and alkalis and would not react with air. He also predicted that M2O3 would dissolve in acids to give MX3 salts, that eka-aluminium salts would form basic salts, that eka-aluminium sulfate should form alums, and that anhydrous MCl3 should have a greater volatility than ZnCl2. All of these predictions were later proven accurate. Gallium was discovered using spectroscopy by French chemist Paul-Émile Lecoq de Boisbaudran in 1875 from its characteristic spectrum (two violet lines) in a sample of sphalerite. Later that year, Lecoq obtained the free metal by electrolysis of the hydroxide in potassium hydroxide solution. He named the element "gallia", from Latin Gallia meaning 'Gaul', a name for his native land of France. It was later claimed that, in a multilingual pun of a kind favoured by men of science in the 19th century, he had also named gallium after himself: Le coq is French for 'the rooster', and the Latin word for 'rooster' is gallus. In an 1877 article, Lecoq denied this conjecture. Originally, de Boisbaudran determined the density of gallium as 4.7 g/cm3, the only property that failed to match Mendeleev's predictions; Mendeleev then wrote to him and suggested that he should remeasure the density, and de Boisbaudran then obtained the correct value of 5.9 g/cm3, that Mendeleev had predicted exactly. From its discovery in 1875 until the era of semiconductors, the primary uses of gallium were high-temperature thermometrics and metal alloys with unusual properties of stability or ease of melting (some such being liquid at room temperature). The development of gallium arsenide as a direct bandgap semiconductor in the 1960s ushered in the most important stage in the applications of gallium. In the late 1960s, the electronics industry started using gallium on a commercial scale to fabricate light emitting diodes, photovoltaics and semiconductors, while the metals industry used it to reduce the melting point of alloys. First blue gallium nitride LED were developed in 1971–1973, but they were feeble. Only in the early 1990s Shuji Nakamura managed to combine GaN with indium gallium nitride and develop the modern blue LED, now making the basis of ubiquitous white LEDs, which Nichia commercialized in 1993. He and two other Japanese scientists received a Nobel in Physics in 2014 for this work. Global gallium production slowly grew from several tens of t/year in the 1970s til ca.

anese in the form of the deep violet salt potassium permanganate is commonly used in laboratories as an oxidizer. Potassium permanganate is also used as a biocide in water treatment. It occurs at the active sites in some enzymes. Of particular interest is the use of a Mn–O cluster, the oxygen-evolving complex, in the production of oxygen by plants. Characteristics Physical properties Manganese is a silvery-gray metal that resembles iron. It is hard and very brittle, difficult to melt, but oxidizes easily. Manganese and its common ions are paramagnetic.

Naturally occurring manganese is composed of one stable isotope, 55Mn. Several radioisotopes have been isolated and described, ranging from 46Mn to 72Mn; the most stable ones are 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.08 days, and 52Mn with a half-life of 5.591 days. All of the remaining radioactive isotopes have half-lives of less than three hours, and the majority of less than one minute. The primary decay mode in isotopes lighter than the most abundant stable isotope, 55Mn, is electron capture, and the primary mode in heavier isotopes is beta decay. Manganese also has three meta states. Manganese is part of the iron group of elements, which are thought to be synthesized in massive stars shortly before the supernova explosion. 53Mn decays to 53Cr with a half-life of 3.7 million years. Because of its short half-life, 53Mn is relatively rare; it is produced by the impact of cosmic rays on iron. Chromium and manganese are found together sufficiently for measurement of both to find application in isotope geology, and the Mn/Cr ratios here for dating the early Solar System. Mn–Cr isotopic ratios reinforce the evidence from 26Al and 107Pd for the early history of the Solar System. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites suggest a non-zero initial 53Mn/55Mn ratio, which indicate that Cr isotopic composition variations must result from in situ decay of 53Mn in differentiated planetary bodies.

Manganese forms a large variety of organometallic derivatives, i.e., compounds with Mn-C bonds. The organometallic derivatives include numerous examples of Mn in its lower oxidation states, i.e. Mn(−III) up through Mn(I). This area of organometallic chemistry is attractive because Mn is inexpensive and of relatively low toxicity. Of greatest commercial interest is methylcyclopentadienyl manganese tricarbonyl (MMT), which is used as an anti-knock compound added to gasoline in some countries, featuring Mn(I). Consistent with other aspects of Mn(II) chemistry, manganocene (Mn(C5H5)2) is high-spin. In contrast, its neighboring metal, iron, forms an air-stable, low-spin derivative in the form of ferrocene (Fe(C5H5)2). When conducted under an atmosphere of carbon monoxide, reduction of Mn(II) salts gives dimanganese decacarbonyl Mn2(CO)10, an orange and volatile solid. The air-stability of this Mn(0) compound (and its many derivatives) reflects the powerful electron-acceptor properties of carbon monoxide. Many alkene complexes and alkyne complexes are derived from Mn2(CO)10. In Mn(CH3)2(dmpe)2, Mn(II) is low spin, which contrasts with the high spin character of its precursor, MnBr2(dmpe)2 (dmpe = (CH3)2PCH2CH2P(CH3)2). Polyalkyl and polyaryl derivatives of manganese often exist in higher oxidation states, reflecting the electron-releasing properties of alkyl and aryl ligands.

Mining engineering is the extraction of minerals from the ground. It is associated with many other disciplines, such as mineral processing, exploration, excavation, geology, metallurgy, geotechnical engineering and surveying.

Once the mineral identification and reserve amount are reasonably determined, the next step is to determine the feasibility of recovering the mineral deposit. A preliminary survey shortly after the discovery of the deposit examines the market conditions, such as the supply and demand of the mineral, the amount of ore needed to be moved to recover a certain quantity of that mineral, and analysis of the cost associated with the operation. This pre-feasibility study determines whether the mining project is likely to be profitable; if so, a more in-depth analysis of the deposit is undertaken. After the full extent of the ore body is known and has been examined by engineers, the feasibility study examines the cost of initial capital investment, methods of extraction, the cost of operation, an estimated length of time to pay back the investment, the gross revenue and net profit margin, any possible resale price of the land, the total life of the reserve, the full value of the account, investment in future projects, and the property owner or owners' contract. In addition, environmental impact, reclamation, possible legal ramifications, and all government permitting are considered. These steps of analysis determine whether the mining company and its investors should proceed with the extraction of the minerals or whether the project should be abandoned. The mining company may decide to sell the rights to the reserve to a third party rather than develop it themselves.

eer may manage any phase of mining operations, from exploration and discovery of the mineral resources, through feasibility study, mine design, development of plans, production and operations to mine closure. History of mining engineering From prehistoric times to the present, mining has played a significant role in the existence of the human race. Since the beginning of civilization, people have used stone and ceramics and, later, metals found on or close to the Earth's surface. These were used to manufacture early tools and weapons. For example, high-quality flint found in northern France and southern England were used to set fire and break rock. Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries. The oldest known mine on the archaeological record is the "Lion Cave" in Eswatini. At this site, which radiocarbon dating indicates to be about 43,000 years old, paleolithic humans mined mineral hematite, which contained iron and was ground to produce the red pigment ochre. The ancient Romans were innovators of mining engineering. They developed large-scale mining methods, such as the use of large volumes of water brought to the minehead by aqueducts for hydraulic mining. The exposed rock was then attacked by fire-setting, where fires were used to heat the rock, which would be quenched with a stream of water. The thermal shock cracked the rock, enabling it to be removed. In some mines, the Romans utilized water-powered machinery such as reverse overshot water-wheels. These were used extensively in the copper mines at Rio Tinto in Spain, where one sequence comprised 16 such wheels arranged in pairs, lifting water about 80 feet (24 m). Black powder was first used in mining in Banská Štiavnica, Kingdom of Hungary (present-day Slovakia) in 1627. This allowed blasting of rock and earth to loosen and reveal ore veins, which was much faster than fire-setting.

able to prepare it and characterize it in pure form. Its oxides form a family of anions known as silicates. Its melting and boiling points of 1414 °C and 3265 °C, respectively, are the second highest among all the metalloids and nonmetals, being surpassed only by boron. Silicon is the eighth most common element in the universe by mass, but very rarely occurs in its pure form in the Earth's crust. It is widely distributed throughout space in cosmic dusts, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. More than 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 28% by mass), after oxygen. Most silicon is used commercially without being separated, often with very little processing of the natural minerals. Such use includes industrial construction with clays, silica sand, and stone. Silicates are used in Portland cement for mortar and stucco, and mixed with silica sand and gravel to make concrete for walkways, foundations, and roads. They are also used in whiteware ceramics such as porcelain, and in traditional silicate-based soda–lime glass and many other specialty glasses. Silicon compounds such as silicon carbide are used as abrasives and components of high-strength ceramics. Silicon is the basis of the widely used synthetic polymers called silicones. The late 20th century to early 21st century has been described as the Silicon Age (also known as the Digital Age or Information Age) because of the large impact that elemental silicon has on the modern world economy. The small portion of very highly purified elemental silicon used in semiconductor electronics (<15%) is essential to the transistors and integrated circuit chips used in most modern technology such as smartphones and other computers. In 2019, 32.4% of the semiconductor market segment was for networks and communications devices, and the semiconductors industry is projected to reach $726.73 billion by 2027. Silicon is an essential element in biology. Only traces are required by most animals, but some sea sponges and microorganisms, such as diatoms and radiolaria, secrete skeletal structures made of silica.

Silicon is the eighth most abundant element in the universe, coming after hydrogen, helium, oxygen, carbon, neon, iron, and nitrogen. This differs from abundance of elements in Earth's crust due to substantial separation of the elements taking place during the formation of the Solar System. Silicon makes up 27.2% of the Earth's crust by weight, second only to oxygen at 45.5%, with which it always is associated in nature. Further fractionation took place in the formation of the Earth by planetary differentiation: Earth's core, which makes up 31.5% of the mass of the Earth, has approximate composition Fe25Ni2Co0.1S3; the mantle makes up 68.1% of the Earth's mass and is composed mostly of denser oxides and silicates, an example being olivine, (Mg,Fe)2SiO4; while the lighter siliceous minerals such as aluminosilicates rise to the surface and form the crust, making up 0.4% of the Earth's mass. The crystallisation of igneous rocks from magma depends on a number of factors; among them are the chemical composition of the magma, the cooling rate, and some properties of the individual minerals to be formed, such as lattice energy, melting point, and complexity of their crystal structure. As magma is cooled, olivine appears first, followed by pyroxene, amphibole, biotite mica, orthoclase feldspar, muscovite mica, quartz, zeolites, and finally, hydrothermal minerals. This sequence shows a trend toward increasingly complex silicate units with cooling, and the introduction of hydroxide and fluoride anions in addition to oxides. Many metals may substitute for silicon. After these igneous rocks undergo weathering, transport, and deposition, sedimentary rocks like clay, shale, and sandstone are formed. Metamorphism also may occur at high temperatures and pressures, creating an even vaster variety of minerals. There are four sources for silicon fluxes into the ocean: chemical weathering of continental rocks, river transport, dissolution of continental terrigenous silicates, and the reaction between submarine basalts and hydrothermal fluid which release dissolved silicon. All four of these fluxes are interconnected in the ocean's biogeochemical cycle as they all were initially formed from the weathering of Earth's crust. Approximately 300–900 megatonnes of aeolian dust is deposited into the world's oceans each year. Of that value, 80–240 megatonnes are in the form of particulate silicon. The total amount of particulate silicon deposition into the ocean is still less than the amount of silicon influx into the ocean via riverine transportation. Aeolian inputs of particulate lithogenic silicon into the North Atlantic and Western North Pacific oceans are the result of dust settling on the oceans from the Sahara and Gobi Desert, respectively.

Alloys Elemental silicon is added to molten iron as ferrosilicon alloys to improve performance in casting thin sections and to prevent the formation of cementite where exposed to outside air. The presence of elemental silicon in molten iron acts as a sink for oxygen, so that the steel carbon content, which must be kept within narrow limits for each type of steel, can be more closely controlled. Around 75% of ferrosilicon produced is used in the steel industry. Silicon is an important constituent of transformer steel, modifying its resistivity and ferromagnetic properties. The properties of silicon may be used to modify alloys with metals other than iron. "Metallurgical grade" silicon is silicon of 95–99% purity. About 55% of the world consumption of metallurgical purity silicon goes for production of aluminium-silicon alloys (silumin alloys) for aluminium part casts, mainly for use in the automotive industry. Silicon's importance in aluminium casting is that a significantly high amount (12%) of silicon in aluminium forms a eutectic mixture which solidifies with very little thermal contraction. This greatly reduces tearing and cracks formed from stress as casting alloys cool to solidity. Silicon also significantly improves the hardness and thus wear-resistance of aluminium. Metallurgical grade silicon is made by melting quartz or quartzite in a large arc furnace, in a carbothermal reduction process with carbon-containing material such as coal, coke or charcoal and woodchips for gas circulation. This production technique without iron is often used for polysilicon production for photovoltaics and also semiconductors. Electronics Silicon semiconductor devices enable modern information technology. The electronic applications are broad, including microelectronics, computing, optoelectronics, and nanotechnology. Among the many advantages of silicon for electronics are: low cost, formation of large pure single crystals, not brittle, conducts heat generated by electrical activity adequately, can be micro-structured and modified in layers, and its oxide is an excellent insulator. An estimated 15% of the world production of metallurgical grade silicon is refined to semiconductor purity. This is typically the "nine-9" or 99.9999999% purity, nearly defect-free single crystalline material. Monocrystalline silicon of such purity is usually produced by the Czochralski process, and is used to produce silicon wafers used in the semiconductor industry, in electronics, and in some high-cost and high-efficiency photovoltaic applications. Pure silicon is an intrinsic semiconductor, which means that unlike metals, it conducts electron holes and electrons released from atoms by heat. Intrinsic silicon's electrical conductivity increases with temperature due to the broadening of the Fermi-Dirac distribution. Pure silicon has too low a conductivity (i.e., too high a resistivity) to be used as a circuit element in electronics. In practice, pure silicon is doped with small concentrations of elements with differing valence electron count (typically boron and phosphorus), which greatly increase its conductivity and adjust its electrical response by controlling the number and type (positive or negative) of activated charge carriers. Such control is necessary for transistors, solar cells, semiconductor detectors, and other semiconductor devices used in the computer industry and other technical applications.

roduct of copper and lead production. Commercially, the primary use of tellurium is CdTe solar panels and thermoelectric devices. A more traditional application in copper (tellurium copper) and steel alloys, where tellurium improves machinability, also consumes a considerable portion of tellurium production. Tellurium has no biological function, although fungi can use it in place of sulfur and selenium in amino acids such as tellurocysteine and telluromethionine.

Tellurium (Latin tellus meaning "earth") was discovered in the 18th century in a gold ore from the mines in Kleinschlatten (today Zlatna), near today's city of Alba Iulia, Romania. This ore was known as "Faczebajer weißes blättriges Golderz" (white leafy gold ore from Faczebaja, German name of Facebánya, now Fața Băii in Alba County) or antimonalischer Goldkies (antimonic gold pyrite), and according to Anton von Rupprecht, was Spießglaskönig (argent molybdique), containing native antimony. In 1782 Franz-Joseph Müller von Reichenstein, who was then serving as the Austrian chief inspector of mines in Transylvania, concluded that the ore did not contain antimony but was bismuth sulfide. The following year, he reported that this was erroneous and that the ore contained mostly gold and an unknown metal very similar to antimony. After a thorough investigation that lasted three years and included more than fifty tests, Müller determined the specific gravity of the mineral and noted that when heated, the new metal gives off a white smoke with a radish-like odor; that it imparts a red color to sulfuric acid; and that when this solution is diluted with water, it has a black precipitate. Nevertheless, he was not able to identify this metal and gave it the names aurum paradoxum (paradoxical gold) and metallum problematicum (problem metal), because it did not exhibit the properties predicted for antimony. In 1789, a Hungarian scientist, Pál Kitaibel, discovered the element independently in an ore from Deutsch-Pilsen that had been regarded as argentiferous molybdenite, but later he gave the credit to Müller. In 1798, it was named by Martin Heinrich Klaproth, who had earlier isolated it from the mineral calaverite. In the early 1920s, Thomas Midgley Jr. found tellurium prevented engine knocking when added to fuel, but ruled it out due to the difficult-to-eradicate smell. Midgley went on to discover and popularize the use of tetraethyl lead. The 1960s brought an increase in thermoelectric applications for tellurium (as bismuth telluride), and in free-machining steel alloys, which became the dominant use. These applications were overtaken by the growing importance of CdTe in thin-film solar cells in the 2000s. Production Most Te (and Se) is obtained from porphyry copper deposits, where it occurs in trace amounts. The element is recovered from anode sludges from the electrolytic refining of blister copper. It is a component of dusts from blast furnace refining of lead. Treatment of 1000 tons of copper ore yields approximately one kilogram (2.2 pounds) of tellurium. The anode sludges contain the selenides and tellurides of the noble metals in compounds with the formula M2Se or M2Te (M = Cu, Ag, Au). At temperatures of 500 °C the anode sludges are roasted with sodium carbonate under air.

Applications In 2022, the major applications of tellurium were thin-film solar cells (40%), thermoelectrics (30%), metallurgy (15%), and rubber (5%), with the first two applications experiencing a rapid increase owing to the worldwide tendency of reducing dependence on the fossil fuel. In metallurgy, tellurium is added to iron, stainless steel, copper, and lead alloys. It improves the machinability of copper without reducing its high electrical conductivity.

o the client. Second-tier suppliers supply to the first tier, and so on, creating a hierarchical structure within the supply network. The phrase "supply chain" may have been first published in a 1905 article in The Independent, which briefly mentioned the difficulty of "keeping a supply chain with India unbroken" during the British expedition to Tibet. Overview A typical supply chain can be divided into two stages namely, production and distribution stages. In the production stage, components and semi-finished parts are produced in manufacturing centres. The components are then put together in an assembly plant. The distribution stage consists of central and regional distribution centres that transport products to end-consumers. Mentzer et al. suggest that at least three entities are required for there to be a "supply chain". At the end of the supply chain, materials and finished products only flow there because of the customer behaviour at the end of the chain; academics Alan Harrison and Janet Godsell argue that "supply chain processes should be coordinated in order to focus on end customer buying behaviour", and look for "customer responsiveness" as an indicator confirming that materials are able to flow "through a sequence of supply chain processes in order to meet end customer buying behaviour". Many of the exchanges encountered in the supply chain take place between varied companies that seek to maximize their revenue within their sphere of interest but may have little or no knowledge or interest in the remaining players in the supply chain. More recently, the loosely coupled, self-organizing network of businesses who cooperate in providing product and service offerings has been called the extended enterprise, and the use of the term "chain" and the linear structure it appears to represent have been criticized as "harder to relate to the way supply networks really operate". A chain is actually a complex and dynamic supply and demand network. As part of their efforts to demonstrate ethical practices, many large companies and global brands are integrating codes of conduct and guidelines into their corporate cultures and management systems. Through these, corporations are making demands on their suppliers (facilities, farms, subcontracted services such as cleaning, canteen, security etc.) and verifying, through social audits, that they are complying with the required standard. A lack of transparency in the supply chain can bar consumers from knowledge of where their purchases originated and facilitate socially irresponsible practices. In 2018, the Loyola University Chicago's Supply and Value Chain Center found in a survey that 53% of supply chain professionals considered ethics to be "extremely" important to their organizations. In some cases, the operation of multiple tiers within a supply chain may give rise to additional costs, due to the "profit layering", where each tier's operators add a profit margin to their costs. For example, in 2015 the UK's Ministry of Justice recognised that its lift maintenance and refurbishment contracts were let to a main contractor who then sub-contracted the work to a specialist lift contractor.

A typical supply chain can be divided into two stages namely, production and distribution stages. In the production stage, components and semi-finished parts are produced in manufacturing centres. The components are then put together in an assembly plant. The distribution stage consists of central and regional distribution centres that transport products to end-consumers. Mentzer et al. suggest that at least three entities are required for there to be a "supply chain". At the end of the supply chain, materials and finished products only flow there because of the customer behaviour at the end of the chain; academics Alan Harrison and Janet Godsell argue that "supply chain processes should be coordinated in order to focus on end customer buying behaviour", and look for "customer responsiveness" as an indicator confirming that materials are able to flow "through a sequence of supply chain processes in order to meet end customer buying behaviour". Many of the exchanges encountered in the supply chain take place between varied companies that seek to maximize their revenue within their sphere of interest but may have little or no knowledge or interest in the remaining players in the supply chain. More recently, the loosely coupled, self-organizing network of businesses who cooperate in providing product and service offerings has been called the extended enterprise, and the use of the term "chain" and the linear structure it appears to represent have been criticized as "harder to relate to the way supply networks really operate". A chain is actually a complex and dynamic supply and demand network. As part of their efforts to demonstrate ethical practices, many large companies and global brands are integrating codes of conduct and guidelines into their corporate cultures and management systems. Through these, corporations are making demands on their suppliers (facilities, farms, subcontracted services such as cleaning, canteen, security etc.) and verifying, through social audits, that they are complying with the required standard. A lack of transparency in the supply chain can bar consumers from knowledge of where their purchases originated and facilitate socially irresponsible practices. In 2018, the Loyola University Chicago's Supply and Value Chain Center found in a survey that 53% of supply chain professionals considered ethics to be "extremely" important to their organizations. In some cases, the operation of multiple tiers within a supply chain may give rise to additional costs, due to the "profit layering", where each tier's operators add a profit margin to their costs. For example, in 2015 the UK's Ministry of Justice recognised that its lift maintenance and refurbishment contracts were let to a main contractor who then sub-contracted the work to a specialist lift contractor. The ministry avoided the cost impact of this arrangement by contracting for lift work directly with the specialist contractors. Typologies Marshall L. Fisher (1997) asks the question in a key article, "Which is the right supply chain for your product?" Fisher, and also Naylor, Naim and Berry (1999), identify two matching characteristics of supply chain strategy: a combination of "functional" and "efficient", or a combination of "responsive" and "innovative" (Harrison and Godsell). Mentzer et al.

A supply chain is a complex logistics system that consists of facilities that convert raw materials into finished products and distribute them to end consumers or end customers, while supply chain management focuses on the optimization of the flow of goods within the supply chain's distribution channels to ensure efficiency. In sophisticated supply chain systems, the reintroduction of used products into the supply chain may occur at any point where the residual value of the product is recyclable. Supply chains are linked to value chains, and suppliers within a supply chain are often organized into tiers. First-tier suppliers, also referred to as "direct suppliers", directly supply goods or services to the client.

assing the entire Solar System, and has made important contributions to the understanding of a number of processes including mantle convection, the formation of planets and the origins of granite and basalt. It is an integrated field of chemistry and geology. History The term geochemistry was first used by the Swiss-German chemist Christian Friedrich Schönbein in 1838: "a comparative geochemistry ought to be launched, before geognosy can become geology, and before the mystery of the genesis of our planets and their inorganic matter may be revealed." However, for the rest of the century the more common term was "chemical geology", and there was little contact between geologists and chemists. Geochemistry emerged as a separate discipline after major laboratories were established, starting with the United States Geological Survey (USGS) in 1884, which began systematic surveys of the chemistry of rocks and minerals. The chief USGS chemist, Frank Wigglesworth Clarke, noted that the elements generally decrease in abundance as their atomic weights increase, and summarized the work on elemental abundance in The Data of Geochemistry. The composition of meteorites was investigated and compared to terrestrial rocks as early as 1850. In 1901, Oliver C. Farrington hypothesised that, although there were differences, the relative abundances should still be the same. This was the beginnings of the field of cosmochemistry and has contributed much of what we know about the formation of the Earth and the Solar System. In the early 20th century, Max von Laue and William L. Bragg showed that X-ray scattering could be used to determine the structures of crystals. In the 1920s and 1930s, Victor Goldschmidt and associates at the University of Oslo applied these methods to many common minerals and formulated a set of rules for how elements are grouped.

Differentiation and mixing The chemical composition of the Earth and other bodies is determined by two opposing processes: differentiation and mixing. In the Earth's mantle, differentiation occurs at mid-ocean ridges through partial melting, with more refractory materials remaining at the base of the lithosphere while the remainder rises to form basalt. After an oceanic plate descends into the mantle, convection eventually mixes the two parts together. Erosion differentiates granite, separating it into clay on the ocean floor, sandstone on the edge of the continent, and dissolved minerals in ocean waters. Metamorphism and anatexis (partial melting of crustal rocks) can mix these elements together again.

ry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the entire Solar System, and has made important contributions to the understanding of a number of processes including mantle convection, the formation of planets and the origins of granite and basalt. It is an integrated field of chemistry and geology.

conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, and constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few native metals, meaning metals that occur naturally in a directly usable, unalloyed metallic form. This led to very early human use in several regions, from c. 8000 BC. Thousands of years later, it was the first metal to be smelted from sulfide ores, c. 5000 BC; the first metal to be cast into a shape in a mold, c. 4000 BC; and the first metal to be purposely alloyed with another metal, tin, to create bronze, c. 3500 BC. Commonly encountered compounds are copper(II) salts, which often impart blue or green colors to such minerals as azurite, malachite, and turquoise, and have been used widely and historically as pigments. Copper used in buildings, usually for roofing, oxidizes to form a green patina of compounds called verdigris. Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as bacteriostatic agents, fungicides, and wood preservatives. Copper is essential to all aerobic organisms. It is particularly associated with oxygen metabolism. For example, it is found in the respiratory enzyme complex cytochrome c oxidase, in the oxygen carrying hemocyanin, and in several hydroxylases.

Recycling According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of copper in use in society is 35–55 kg. Much of this is in more-developed countries (140–300 kg per capita) rather than less-developed countries (30–40 kg per capita). In 2001, a typical automobile contained 20–30 kg of copper. By 2014, the copper and copper alloy content of internal combustion engine vehicles decreased to 16.8 kg, but increased again to 24.5 kg by 2023. At the same time, a battery electric vehicle already contains around 91 kg of copper and copper alloys. Like aluminium, copper is recyclable without any loss of quality, both from raw state and from manufactured products. An estimated 80% of all copper ever mined is still in use today. In volume, copper is the third most recycled metal after iron and aluminium. As of 2023, recycled copper supplies about one-third of global demand. The process of recycling copper is roughly the same as is used to extract copper but requires fewer steps. High-purity scrap copper is melted in a furnace and then reduced and cast into billets and ingots.

Copper mining is energy intensive. The extraction generates a substantial waste stream, including potentially toxic dust and heavy metal contamination near sites where it is refined. Since most copper ores are sulfides, smelting is required. Smelting generates sulfur dioxide, a precursor to atmospheric sulfuric acid, unless it is captured. About 15% of copper comes from low grade (dilute) ore bodies. Processing is achieved by hydrometallurgy, requiring acidic extractants, which remains in the waste streams after electrolytic deposition of the copper. Alloys Numerous copper alloys have been formulated, many with important uses. Brass is an alloy of copper and zinc. Bronze usually refers to copper–tin alloys, but can refer to any alloy of copper such as aluminium bronze. Copper-tin bronzes with various additional metals have been used to create bells for centuries; the composition of the alloy directly affects the tone and mechanical characteristics of the instrument. Copper is one of the most important constituents of silver and karat gold solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys. Some lead-free solders consist of tin alloyed with a small proportion of copper and other metals. The alloy of copper and nickel, called cupronickel, is used in low-denomination coins, often for the outer cladding. The US five-cent coin (currently called a nickel) consists of 75% copper and 25% nickel in homogeneous composition. Prior to the introduction of cupronickel, which was widely adopted by countries in the latter half of the 20th century, alloys of copper and silver were also used, with the United States using an alloy of 90% silver and 10% copper until 1965, when circulating silver was removed from all coins with the exception of the half dollar—these were debased to an alloy of 40% silver and 60% copper between 1965 and 1970. The alloy of 90% copper and 10% nickel, remarkable for its resistance to corrosion, is used for various objects exposed to seawater, though it is vulnerable to the sulfides sometimes found in polluted harbors and estuaries. Alloys of copper with aluminium (about 7%) have a golden color and are used in decorations.

anadium ions are found in a few organisms, possibly as a toxin. The oxide and some other salts of vanadium have moderate toxicity. Particularly in the ocean, vanadium is used by some life forms as an active center of enzymes, such as the vanadium bromoperoxidase of some ocean algae. History Vanadium was discovered in Mexico in 1801 by the Spanish mineralogist Andrés Manuel del Río. Del Río extracted the element from a sample of Mexican "brown lead" ore, later named vanadinite. He found that its salts exhibit a wide variety of colors, and as a result, he named the element panchromium (Greek: παγχρώμιο "all colors"). Later, del Río renamed the element erythronium (Greek: ερυθρός "red") because most of the salts turned red upon heating. In 1805, French chemist Hippolyte Victor Collet-Descotils, backed by del Río's friend Baron Alexander von Humboldt, incorrectly declared that del Río's new element was an impure sample of chromium. Del Río accepted Collet-Descotils' statement and retracted his claim. In 1831 Swedish chemist Nils Gabriel Sefström rediscovered the element in a new oxide he found while working with iron ores. Later that year, Friedrich Wöhler confirmed that this element was identical to that found by del Río and hence confirmed del Río's earlier work. Sefström chose a name beginning with V, which had not yet been assigned to any element. He called the element vanadium after Old Norse Vanadís (another name for the Norse Vanir goddess Freyja, whose attributes include beauty and fertility), because of the many beautifully colored chemical compounds it produces. On learning of Wöhler's findings, del Río began to passionately argue that his old claim be recognized, but the element kept the name vanadium. In 1831, the geologist George William Featherstonhaugh suggested that vanadium should be renamed "rionium" after del Río, but this suggestion was not followed. As vanadium is usually found combined with other elements, the isolation of vanadium metal was difficult. In 1831, Berzelius reported the production of the metal, but Henry Enfield Roscoe showed that Berzelius had produced the nitride, vanadium nitride (VN). Roscoe eventually produced the metal in 1867 by reduction of vanadium(II) chloride, VCl2, with hydrogen. In 1927, pure vanadium was produced by reducing vanadium pentoxide with calcium. The first large-scale industrial use of vanadium was in the steel alloy chassis of the Ford Model T, inspired by French race cars. Vanadium steel allowed reduced weight while increasing tensile strength (c. 1905). For the first decade of the 20th century, most vanadium ore was mined by the American Vanadium Company from the Minas Ragra in Peru. Later, the demand for uranium rose, leading to increased mining of that metal's ores. One major uranium ore was carnotite, which also contains vanadium. Thus, vanadium became available as a by-product of uranium production.

Vanadium is an average-hard, ductile, steel-blue metal. Vanadium is usually described as "soft", because it is ductile, malleable, and not brittle. Vanadium is harder than most metals and steels (see Hardnesses of the elements (data page) and iron). It has good resistance to corrosion and it is stable against alkalis and sulfuric and hydrochloric acids. It is oxidized in air at about 933 K (660 °C, 1220 °F), although an oxide passivation layer forms even at room temperature. It also reacts with hydrogen peroxide. Isotopes Naturally occurring vanadium is composed of one stable isotope, 51V, and one radioactive isotope, 50V. The latter has a half-life of 2.71×1017 years and a natural abundance of 0.25%. 51V has a nuclear spin of 7⁄2 and can be used for NMR spectroscopy. Twenty-five artificial radioisotopes have been characterized, ranging in mass number from 42 to 68. The most stable of these isotopes are 49V with a half-life of 330 days, and 48V with a half-life of 15.97 days. The remaining radioactive isotopes have half-lives shorter than an hour, most below 10 seconds. Electron capture is the main decay mode for isotopes lighter than 51V. For the heavier ones, the most common mode is beta decay.

Naturally occurring vanadium is composed of one stable isotope, 51V, and one radioactive isotope, 50V. The latter has a half-life of 2.71×1017 years and a natural abundance of 0.25%. 51V has a nuclear spin of 7⁄2 and can be used for NMR spectroscopy. Twenty-five artificial radioisotopes have been characterized, ranging in mass number from 42 to 68. The most stable of these isotopes are 49V with a half-life of 330 days, and 48V with a half-life of 15.97 days. The remaining radioactive isotopes have half-lives shorter than an hour, most below 10 seconds. Electron capture is the main decay mode for isotopes lighter than 51V. For the heavier ones, the most common mode is beta decay.

the agency also provides state and local governments with experts in specialized fields, funding for rebuilding efforts, and relief funds for infrastructure (re)development. It also helps individuals access low-interest disaster recovery loans, in conjunction with the Small Business Administration.

These teams provide communications support to local public safety. For instance, they may operate a truck with satellite uplink, computers, telephone, and power generation at a staging area near a disaster so that the responders can communicate with the outside world. There are also Mobile Air Transportable Telecommunications System (MATTS) assets which can be airlifted in. Also, portable cell phone towers can be erected to allow local responders to access telephone systems. The first test of the national wireless emergency system by FEMA was broadcast to an estimated 225 million electronic devices at 14:18 EDT on October 3, 2018. The text message was accompanied by a flashing warning sign and warning tone. The president may direct FEMA to broadcast such alerts only for national emergencies or if the public is in danger. The facility may not be used for personal messages from the president.

In early April 2020, the Los Angeles Times reported that the Trump administration was "quietly" seizing medical supplies from states and hospitals, citing hospital and clinic officials catering to seven states. These officials stated that the administration has not informed them how they can otherwise get access to their ordered supplies. A FEMA representative said the agency, working with the Department of Health and Human Services and the Department of Defense, has developed a system for identifying needed supplies from vendors and distributing them equitably. The federal government also seized an order for thermometers meant for Florida, an order for masks from the Texas Association of Community Health Centers, and an order for testing supplies meant for the PeaceHealth hospital system in Washington, Oregon and Alaska. On April 24, San Francisco Mayor London Breed said "We've had situations when things we've ordered that have gone through Customs were confiscated by FEMA to be diverted to other locations. We know everyone is dealing with a serious challenge. Through Customs, we've had situations where those items have been taken and put out on the market for the highest bidder, putting cities against cities and states against states." Massachusetts Secretary of Health and Human Services Marylou Sudders cited a shipment of 3 million masks that the state had negotiated to buy from BJ's Wholesale Club, until the federal government impounded them from the Port of New York and New Jersey on March 18. A further order from MSC Industrial Supply for 400 masks to be delivered on March 20 was also claimed by the federal government using force majeure. Massachusetts Governor Charlie Baker reached out to the New England Patriots professional American football team, who used the team plane "AirKraft" to bring approximately 1.2 million N95 masks from China to Boston. In late April, reports of the actions taken by FEMA in Massachusetts prompted Maryland Governor Larry Hogan to deploy the Maryland National Guard and task them with guarding a shipment of 500,000 COVID-19 testing kits purchased from South Korean company LabGenomics by the Government of Maryland. The tests were subsequently held in an "undisclosed location," under the continued supervision of the Maryland National Guard. The state of Colorado was set to purchase 500 ventilators before Federal Emergency Management Agency swooped in and bought them first. President Trump announced on Twitter that the federal government would be sending 100 ventilators to Colorado at the request of Senator Cory Gardner. The incident caused Colorado Governor Polis to make future supply purchases in secret. In late April, 5,000,000 masks meant for hospitals of the Veterans Health Administration were seized by FEMA and redirected to the Strategic National Stockpile, stated Richard Stone, Executive in Charge, Veterans Health Administration.

nt to investigate Earth and planetary systems across diverse spatial and temporal scales. Its methods include field measurements, laboratory experiments, remote sensing, numerical modelling, and data analysis of both natural and instrumented records, including signal processing.

agnetic compasses, and later extending to Newtonian analyses of tides, precession, and Earth’s physical properties. Today, geophysics is pursued for fundamental scientific understanding and practical applications, including the exploration of mineral and energy resources, assessment and mitigation of natural hazards, groundwater and environmental studies, archaeological investigations, and environmental monitoring. Geophysics integrates theory, observation, and experiment to investigate Earth and planetary systems across diverse spatial and temporal scales. Its methods include field measurements, laboratory experiments, remote sensing, numerical modelling, and data analysis of both natural and instrumented records, including signal processing.

International Union of Geodesy and Geophysics (IUGG) Sociedade Brasileira de Geofísica Earth system science – Scientific study of the Earth's spheres and their natural integrated systems List of geophysicists Outline of geophysics – Topics in the physics of the Earth and its vicinity Geodynamics – Study of dynamics of the Earth Planetary science – Science of planets and planetary systems Geological Engineering Physics Space physics Geosciences Geodesy Aeromagnetic survey Notes References External links A reference manual for near-surface geophysics techniques and applications Archived 18 February 2021 at the Wayback Machine Commission on Geophysical Risk and Sustainability (GeoRisk), International Union of Geodesy and Geophysics (IUGG) Study of the Earth's Deep Interior,

and four navigation dams on its lower section created a shipping channel to Lewiston, Idaho – the furthest inland seaport on the West Coast. While dam construction, commercial fishing and other human activities have greatly reduced anadromous fish populations since the late 19th century, the Snake River watershed is still considered important habitat for these fish. The Snake and its tributary, the Salmon River, host the longest sockeye salmon run in the world, stretching 900 miles (1,400 km) from the Pacific to Redfish Lake in Idaho. Since the 1950s, public agencies, tribal governments and private utilities have invested heavily in fishery restoration and hatchery programs, with limited success.

sh. The Snake and its tributary, the Salmon River, host the longest sockeye salmon run in the world, stretching 900 miles (1,400 km) from the Pacific to Redfish Lake in Idaho. Since the 1950s, public agencies, tribal governments and private utilities have invested heavily in fishery restoration and hatchery programs, with limited success.

As gold mining declined in the late 19th century, the wheat industry boomed in the Palouse of southeast Washington. By the 1870s, the Oregon Steam Navigation Company was operating seven steamboats transporting grain from the Snake River to lower Columbia River ports. These were the Harvest Queen, John Gates, Spokane, Annie Faxon, Mountain Queen, R.R. Thompson, and Wide West. In the 1890s, a huge copper deposit was discovered at Eureka Bar in Hells Canyon. Several ships transported ore from there to Lewiston, including Imnaha, Mountain Gem, and Norma. In 1893 the Annie Faxon suffered a boiler explosion and sank on the Snake below Lewiston, killing five people. Starting in the 1880s, the Army Corps began dredging the Snake River below Lewiston to maintain a 5-foot (1.5 m) deep navigation channel. River traffic declined rapidly once railroads arrived. By 1899, the Union Pacific line along the south bank of the Snake River had reached Riparia, Washington. It then joined forces with the Northern Pacific Railroad, which was building a line along the north bank, to build the shared Camas Prairie Railroad the rest of the way to Lewiston, which it reached in 1908. The Open River Transportation Company, which operated steamboats between Lewiston and Celilo Falls on the Columbia, went bankrupt in 1912. The 1915 completion of the Celilo Canal made it much easier for boats from the upper Columbia and Snake to reach Portland, and the Columbia River Transportation Company began operating a water route between Lewiston and Portland. Still, steamboats were unable to compete with railroads on speed and efficiency. The last steamboat on the lower Snake ran in 1920. Once the railroads monopolized grain shipments, they raised shipping rates, to farmers' consternation. In 1934, political activist Herbert G. West organized the Inland Empire Waterways Association (IEWA), to promote an "open river" – a deep-water shipping channel on the Snake and Columbia Rivers that could compete with rail. The IEWA initially pushed for improvements such as bigger locks at Bonneville Dam in 1938 and the construction of McNary Dam on the Columbia, which would improve navigation to the mouth of the Snake. In 1941 a bill was first introduced in Congress authorizing the Army Corps to develop the lower Snake River. The 1941 bill failed, but after several years of debate, Congress finally authorized the Snake River development in 1945. Early plans included anywhere from six to ten low dams for the lower Snake. Eventually this was reduced to four bigger dams, which would lower costs, but would require what at the time were the tallest navigation locks in the world, at over 100 feet (30 m). Tribes, state wildlife agencies and the fishing industry opposed the dams, arguing that they would kill too many salmon. In 1947, the U.S. Department of the Interior proposed a ten-year moratorium on dam construction while the fishery problem was studied. With the onset of the Cold War, rising electricity demand in the Pacific Northwest – particularly at the nearby Hanford nuclear site – turned the project's focus towards hydropower. By 1948, the Army Corps estimated that over 80 percent of the economic benefits would come from power, and only 15 percent from navigation. Dam opponents countered that if the primary objective was now power, other dam sites existed in the Northwest that would have less impact on fish. These objections proved futile, as the lower Snake River dams were already authorized, and the federal government had little interest in studying alternatives. While opponents continued to stall the project for a few more years, Washington Senator Warren G.

A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities ("doping") to its crystal structure. When two regions with different doping levels are present in the same crystal, they form a semiconductor junction. The term "semiconductors" is sometimes used to refer to semiconductor devices such as microchips and computer processors, which work using the physical properties of semiconductors. The behavior of charge carriers, which include electrons, ions, and electron holes, at these junctions is the basis of diodes, transistors, and most modern electronics. Some examples of semiconductors are silicon, germanium, gallium arsenide, and elements near the so-called "metalloid staircase" on the periodic table. After silicon, gallium arsenide is the second-most common semiconductor and is used in laser diodes, solar cells, microwave-frequency integrated circuits, and others. Silicon is a critical element for fabricating most electronic circuits. Semiconductor devices can display a range of different useful properties, such as passing current more easily in one direction than the other, showing variable resistance, and having sensitivity to light or heat. Because the electrical properties of a semiconductor material can be modified by doping and by the application of electrical fields or light, devices made from semiconductors can be used for amplification, switching, and energy conversion. The term semiconductor is also used to describe materials used in high capacity, medium- to high-voltage cables as part of their insulation, and these materials are often plastic XLPE (cross-linked polyethylene) with carbon black. The conductivity of silicon can be increased by adding a small amount (of the order of 1 in 108) of pentavalent (antimony, phosphorus, or arsenic) or trivalent (boron, gallium, indium) atoms. This process is known as doping, and the resulting semiconductors are known as doped or extrinsic semiconductors. Apart from doping, the conductivity of a semiconductor can be improved by increasing its temperature. This is contrary to the behavior of a metal, in which conductivity decreases with an increase in temperature. The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of charge carriers in a crystal lattice. Doping greatly increases the number of charge carriers within the crystal. When a semiconductor is doped by Group V elements, they will behave like donors creating free electrons, known as "n-type" doping. When a semiconductor is doped by Group III elements, they will behave like acceptors creating free holes, known as "p-type" doping. The semiconductor materials used in electronic devices are doped under precise conditions to control the concentration and regions of p- and n-type dopants. A single semiconductor device crystal can have many p- and n-type regions; the p–n junctions between these regions are responsible for the useful electronic behavior. Using a hot-point probe, one can determine quickly whether a semiconductor sample is p- or n-type. A few of the properties of semiconductor materials were observed throughout the mid-19th and first decades of the 20th century. The first practical application of semiconductors in electronics was the 1904 development of the cat's-whisker detector, a primitive semiconductor diode used in early radio receivers.

, medium- to high-voltage cables as part of their insulation, and these materials are often plastic XLPE (cross-linked polyethylene) with carbon black. The conductivity of silicon can be increased by adding a small amount (of the order of 1 in 108) of pentavalent (antimony, phosphorus, or arsenic) or trivalent (boron, gallium, indium) atoms. This process is known as doping, and the resulting semiconductors are known as doped or extrinsic semiconductors. Apart from doping, the conductivity of a semiconductor can be improved by increasing its temperature. This is contrary to the behavior of a metal, in which conductivity decreases with an increase in temperature. The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of charge carriers in a crystal lattice. Doping greatly increases the number of charge carriers within the crystal. When a semiconductor is doped by Group V elements, they will behave like donors creating free electrons, known as "n-type" doping. When a semiconductor is doped by Group III elements, they will behave like acceptors creating free holes, known as "p-type" doping. The semiconductor materials used in electronic devices are doped under precise conditions to control the concentration and regions of p- and n-type dopants. A single semiconductor device crystal can have many p- and n-type regions; the p–n junctions between these regions are responsible for the useful electronic behavior. Using a hot-point probe, one can determine quickly whether a semiconductor sample is p- or n-type. A few of the properties of semiconductor materials were observed throughout the mid-19th and first decades of the 20th century. The first practical application of semiconductors in electronics was the 1904 development of the cat's-whisker detector, a primitive semiconductor diode used in early radio receivers.

Semiconductors are defined by their unique electric conductive behavior, somewhere between that of a conductor and an insulator. The differences between these materials can be understood in terms of the quantum states for electrons, each of which may contain zero or one electron (by the Pauli exclusion principle). These states are associated with the electronic band structure of the material. Electrical conductivity arises due to the presence of electrons in states that are delocalized (extending through the material), however in order to transport electrons a state must be partially filled, containing an electron only part of the time. If the state is always occupied with an electron, then it is inert, blocking the passage of other electrons via that state. The energies of these quantum states are critical since a state is partially filled only if its energy is near the Fermi level (see Fermi–Dirac statistics). High conductivity in a material comes from it having many partially filled states and much state delocalization. Metals are good electrical conductors and have many partially filled states with energies near their Fermi level. Insulators, by contrast, have few partially filled states, their Fermi levels sit within band gaps with few energy states to occupy. Importantly, an insulator can be made to conduct by increasing its temperature: heating provides energy to promote some electrons across the band gap, inducing partially filled states in both the band of states beneath the band gap (valence band) and the band of states above the band gap (conduction band). An (intrinsic) semiconductor has a band gap that is smaller than that of an insulator and at room temperature, significant numbers of electrons can be excited to cross the band gap. A pure semiconductor, however, is not very useful, as it is neither a very good insulator nor a very good conductor. However, one important feature of semiconductors (and some insulators, known as semi-insulators) is that their conductivity can be increased and controlled by doping with impurities and gating with electric fields. Doping and gating move either the conduction or valence band much closer to the Fermi level and greatly increase the number of partially filled states. Some wider-bandgap semiconductor materials are sometimes referred to as semi-insulators. When undoped, these have electrical conductivity nearer to that of electrical insulators, however they can be doped (making them as useful as semiconductors). Semi-insulators find niche applications in micro-electronics, such as substrates for HEMT. An example of a common semi-insulator is gallium arsenide. Some materials, such as titanium dioxide, can even be used as insulating materials for some applications, while being treated as wide-gap semiconductors for other applications. Charge carriers (electrons and holes) The partial filling of the states at the bottom of the conduction band can be understood as adding electrons to that band. The electrons do not stay indefinitely (due to the natural thermal recombination) but they can move around for some time. The actual concentration of electrons is typically very dilute, and so (unlike in metals) it is possible to think of the electrons in the conduction band of a semiconductor as a sort of classical ideal gas, where the electrons fly around freely without being subject to the Pauli exclusion principle. In most semiconductors, the conduction bands have a parabolic dispersion relation, and so these electrons respond to forces (electric field, magnetic field, etc.) much as they would in a vacuum, though with a different effective mass. Because the electrons behave like an ideal gas, one may also think about conduction in very simplistic terms such as the Drude model, and introduce concepts such as electron mobility. For partial filling at the top of the valence band, it is helpful to introduce the concept of an electron hole. Although the electrons in the valence band are always moving around, a completely full valence band is inert, not conducting any current. If an electron is taken out of the valence band, then the trajectory that the electron would normally have taken is now missing its charge. For the purposes of electric current, this combination of the full valence band, minus the electron, can be converted into a picture of a completely empty band containing a positively charged particle that moves in the same way as the electron. Combined with the negative effective mass of the electrons at the top of the valence band, we arrive at a picture of a positively charged particle that responds to electric and magnetic fields just as a normal positively charged particle would do in a vacuum, again with some positive effective mass.

recorded history. In the past, a gold standard was often implemented as a monetary policy. Most gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a fiat currency system after the Nixon shock measures of 1971. In 2023, the world's largest gold producer was China, followed by Russia and Australia. As of 2020, a total of around 201,296 tonnes of gold exist above ground. If all of this gold were put together into a cube shape, each of its sides would measure 21.7 meters (71 ft). The world's consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold's high malleability, ductility, resistance to corrosion and most other chemical reactions, as well as conductivity of electricity have led to its continued use in corrosion-resistant electrical connectors in all types of computerized devices (its chief industrial use). Gold is also used in infrared shielding, the production of colored glass, gold leafing, and tooth restoration.

Gold has been widely used throughout the world as money, for efficient indirect exchange (versus barter), and to store wealth in hoards. For exchange purposes, mints produce standardized gold bullion coins, bars and other units of fixed weight and purity. The first known coins containing gold were struck in Lydia, Asia Minor, around 600 BC. The talent coin of gold in use during the periods of Grecian history both before and during the time of the life of Homer weighed between 8.42 and 8.75 grams. From an earlier preference in using silver, European economies re-established the minting of gold as coinage during the thirteenth and fourteenth centuries. Bills (that mature into gold coin) and gold certificates (convertible into gold coin at the issuing bank) added to the circulating stock of gold standard money in most 19th century industrial economies. In preparation for World War I the warring nations moved to fractional gold standards, inflating their currencies to finance the war effort. Post-war, the victorious countries, most notably Britain, gradually restored gold-convertibility, but international flows of gold via bills of exchange remained embargoed; international shipments were made exclusively for bilateral trades or to pay war reparations. After World War II gold was replaced by a system of nominally convertible currencies related by fixed exchange rates following the Bretton Woods system. Gold standards and the direct convertibility of currencies to gold have been abandoned by world governments, led in 1971 by the United States' refusal to redeem its dollars in gold. Fiat currency now fills most monetary roles. Switzerland was the last country to tie its currency to gold; this was ended by a referendum in 1999. Central banks continue to keep a portion of their liquid reserves as gold in some form, and metals exchanges such as the London Bullion Market Association still clear transactions denominated in gold, including future delivery contracts. Today, gold mining output is declining. With the sharp growth of economies in the 20th century, and increasing foreign exchange, the world's gold reserves and their trading market have become a small fraction of all markets and fixed exchange rates of currencies to gold have been replaced by floating prices for gold and gold future contract. Though the gold stock grows by only 1% or 2% per year, very little metal is irretrievably consumed. Inventory above ground would satisfy many decades of industrial and even artisan uses at current prices. The gold proportion (fineness) of alloys is measured by karat (k). Pure gold (commercially termed fine gold) is designated as 24 karat, abbreviated 24k. English gold coins intended for circulation from 1526 into the 1930s were typically a standard 22k alloy called crown gold, for hardness (American gold coins for circulation after 1837 contain an alloy of 0.900 fine gold, or 21.6 kt). Often the prices of various platinum group metals can be much higher than gold, although gold has been used as a standard for currencies to a greater degree than the platinum group metals. Gold has been used as a symbol for purity, value, royalty, and particularly roles that combine these properties. Gold as a sign of wealth and prestige was ridiculed by Thomas More in his treatise Utopia. On that imaginary island, gold is so abundant that it is used to make chains for slaves, tableware, and lavatory seats. When ambassadors from other countries arrive, dressed in ostentatious gold jewels and badges, the Utopians mistake them for menial servants, paying homage instead to the most modestly dressed of their party. The ISO 4217 currency code of gold is XAU. Many holders of gold store it in form of bullion coins or bars as a hedge against inflation or other economic disruptions. A paper by the National Bureau of Economic Research found that gold may be reliable as an inflation hedge over long timescales (centuries) but not over practical timescales. Modern bullion coins for investment or collector purposes do not require good mechanical wear properties; they are typically fine gold at 24k, although the American Gold Eagle and the British gold sovereign continue to be minted in 22k (0.92) metal in historical tradition, and the South African Krugerrand, first released in 1967, is also 22k (0.92). The special issue Canadian Gold Maple Leaf coin contains the highest purity gold of any bullion coin, at 99.999% or 0.99999, while the popular issue Canadian Gold Maple Leaf coin has a purity of 99.99%. In 2006, the United States Mint began producing the American Buffalo gold bullion coin with a purity of 99.99%. The Australian Gold Kangaroos were first coined in 1986 as the Australian Gold Nugget but changed the reverse design in 1989.

metallic substances, giving rise to the term "acid test". Gold dissolves in alkaline solutions of cyanide, which are used in mining and electroplating. Gold also dissolves in mercury, forming amalgam alloys, and as the gold acts simply as a solute, this is not a chemical reaction. A relatively rare element when compared to silver (though thirty times more common than platinum), gold is a precious metal that has been used for coinage, jewelry, and other works of art throughout recorded history. In the past, a gold standard was often implemented as a monetary policy. Most gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a fiat currency system after the Nixon shock measures of 1971. In 2023, the world's largest gold producer was China, followed by Russia and Australia. As of 2020, a total of around 201,296 tonnes of gold exist above ground. If all of this gold were put together into a cube shape, each of its sides would measure 21.7 meters (71 ft). The world's consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold's high malleability, ductility, resistance to corrosion and most other chemical reactions, as well as conductivity of electricity have led to its continued use in corrosion-resistant electrical connectors in all types of computerized devices (its chief industrial use). Gold is also used in infrared shielding, the production of colored glass, gold leafing, and tooth restoration.

In organic chemistry, phosphate or orthophosphate is an organophosphate, an ester of orthophosphoric acid of the form PO4RR′R″ where one or more hydrogen atoms are replaced by organic groups. An example is trimethyl phosphate, (CH3)3PO4. The term also refers to the trivalent functional group OP(O−)3 in such esters. Phosphates may contain sulfur in place of one or more oxygen atoms (thiophosphates and organothiophosphates). Orthophosphates are especially important among the various phosphates because of their key roles in biochemistry, biogeochemistry, and ecology, and their economic importance for agriculture and industry. The addition and removal of phosphate groups (phosphorylation and dephosphorylation) are key steps in cell metabolism. Phosphates are a major component of agricultural fertilizers and play an important role in plant growth. Since phosphates stimulate plant growth, too much phosphate in the environment can cause pollution in the environment and lead to excessive plant growth. Phosphates are mined around the world for use in agriculture and industry.

In soils Calcium hydroxyapatite and calcite precipitates can be found around bacteria in alluvial topsoil. As clay minerals promote biomineralization, the presence of bacteria and clay minerals resulted in calcium hydroxyapatite and calcite precipitates. Phosphates often adsorb to soil mineral surfaces, mainly Fe- and Al- (oxyhydr)oxides. Goethite is one particularly common and important form of iron for these bonds. High pH can reduce adsorption capacity of these minerals. Phosphate may also adsorb to the edges of clay minerals including koalinite, montmorillonite, and illite. Soil organic matter competes with phosphates for adsorption sites, so soils with high organic matter content have reduced capacity to adsorb phosphate. Pollution Phosphate is a main component of many fertilizers. After application to agricultural fields, rain may wash excess phosphate into nearby water bodies. Demand for phosphate fertilizers is increasing, likely increasing the impact on water bodies. Other sources of phosphate to the environment include detergent, sewage, and residential fertilizer use. Some countries have created laws regulating phosphate in detergents to reduce the phosphate pollution from detergents (see Phosphates in detergent). Addition of high levels of phosphate to environments can have significant ecological consequences such as excessive plant growth. In freshwaters, large algal growth can result in depletion of oxygen as bacteria feed on dead algae (see eutrophication).

Phosphates are the naturally occurring form of the element phosphorus, found in many phosphate minerals. In mineralogy and geology, phosphate refers to a rock or ore containing phosphate ions. Inorganic phosphates are mined to obtain phosphorus for use in agriculture and industry. The largest global producer and exporter of phosphates is China, with Morocco possessing the greatest known reserves. Within North America, the largest deposits lie in the Bone Valley region of central Florida, the Soda Springs region of southeastern Idaho, and the coast of North Carolina. Smaller deposits are located in Montana, Tennessee, Georgia, and South Carolina. The small island nation of Nauru and its neighbor Banaba Island, which used to have massive phosphate deposits of the best quality, have been mined excessively.

of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining and is therefore considered an ore. A complex ore is one containing more than one valuable mineral. Minerals of interest are generally oxides, sulfides, silicates, or native metals such as copper or gold. Ore bodies are formed by a variety of geological processes generally referred to as ore genesis and can be classified based on their deposit type. Ore is extracted from the earth through mining and treated or refined, often via smelting, to extract the valuable metals or minerals.

Magmatic deposits Magmatic deposits are ones which originate directly from magma Pegmatites are very coarse grained, igneous rocks. They crystallize slowly at great depth beneath the surface, leading to their very large crystal sizes. Most are of granitic composition. They are a large source of industrial minerals such as quartz, feldspar, spodumene, petalite, and rare lithophile elements. Carbonatites are an igneous rock whose volume is made up of over 50% carbonate minerals. They are produced from mantle derived magmas, typically at continental rift zones. They contain more rare earth elements than any other igneous rock, and as such are a major source of light rare earth elements. Magmatic Sulfide Deposits form from mantle melts which rise upwards, and gain sulfur through interaction with the crust. This causes the sulfide minerals present to be immiscible, precipitating out when the melt crystallizes. Magmatic sulfide deposits can be subdivided into two groups by their dominant ore element: Ni-Cu, found in komatiites, anorthosite complexes, and flood basalts. This also includes the Sudbury Nickel Basin, the only known astrobleme source of such ore. Platinum Group Elements (PGE) from large mafic intrusions and tholeiitic rock. Stratiform Chromites are strongly linked to PGE magmatic sulfide deposits. These highly mafic intrusions are a source of chromite, the only chromium ore. They are so named due to their strata-like shape and formation via layered magmatic injection into the host rock. Chromium is usually located within the bottom of the intrusion. They are typically found within intrusions in continental cratons, the most famous example being the Bushveld Complex in South Africa. Podiform Chromitites are found in ultramafic oceanic rocks resulting from complex magma mixing. They are hosted in serpentine and dunite rich layers and are another source of chromite. Kimberlites are a primary source for diamonds.

Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. Ore grade refers to the concentration of the desired material it contains. The value of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining and is therefore considered an ore. A complex ore is one containing more than one valuable mineral. Minerals of interest are generally oxides, sulfides, silicates, or native metals such as copper or gold. Ore bodies are formed by a variety of geological processes generally referred to as ore genesis and can be classified based on their deposit type. Ore is extracted from the earth through mining and treated or refined, often via smelting, to extract the valuable metals or minerals.

strial methods for refining antimony from stibnite are roasting followed by reduction with carbon, or direct reduction of stibnite with iron. The most common applications for metallic antimony are in alloys with lead and tin, which have improved properties for solders, bullets, and plain bearings. It improves the rigidity of lead-alloy plates in lead–acid batteries. Antimony trioxide is a prominent additive for halogen-containing flame retardants.

Flame retardants Antimony is mainly used as the trioxide for flame-proofing compounds, always in combination with halogenated flame retardants except in halogen-containing polymers. The flame retarding effect of antimony trioxide is produced by the formation of halogenated antimony compounds, which react with hydrogen atoms, and probably also with oxygen atoms and OH radicals, thus inhibiting fire. Markets for these flame-retardants include children's clothing, toys, aircraft, and automobile seat covers. They are also added to polyester resins in fiberglass composites for such items as light aircraft engine covers. The resin will burn in the presence of an externally generated flame, but will extinguish when the external flame is removed. Antimony trioxide is also used as a synergist with brominated flame retardants in housings and plastic parts for electrical and electronic equipment (e.g., HIPS/ABS enclosures) to meet flammability standards such as UL 94. Alloys Antimony forms a highly useful alloy with lead, increasing its hardness and mechanical strength. When casting it increases fluidity of the melt and reduces shrinkage during cooling. For most applications involving lead, varying amounts of antimony are used as alloying metal. In lead–acid batteries, this addition improves plate strength and charging characteristics. For sailboats, lead keels are used to provide righting moment, ranging from 600 lbs to over 200 tons for the largest sailing superyachts; to improve hardness and tensile strength of the lead keel, antimony is mixed with lead between 2% and 5% by volume.

Alloys Antimony forms a highly useful alloy with lead, increasing its hardness and mechanical strength. When casting it increases fluidity of the melt and reduces shrinkage during cooling. For most applications involving lead, varying amounts of antimony are used as alloying metal. In lead–acid batteries, this addition improves plate strength and charging characteristics. For sailboats, lead keels are used to provide righting moment, ranging from 600 lbs to over 200 tons for the largest sailing superyachts; to improve hardness and tensile strength of the lead keel, antimony is mixed with lead between 2% and 5% by volume.

, Arts & Sciences, and Education; MPA program in the School of Public Service; and the MPH program in the College of Health Sciences. It is classified among "R2: Doctoral Universities – High research activity".

The university also has an honors college. Within the College of Arts and Sciences is the School of the Environment, approved by the Idaho State Board of Education in 2022 and established in 2023. Boise State's fall enrollment in 2016 was 23,886 students, and approximately 76 percent of these students were Idaho residents. More than 90 percent of Boise State's first-year students come directly from high school. In the 2015–16 school year, Boise State awarded diplomas to 3,916 distinct graduates, including 18 doctorates, 10 education specialists, 670 master's and 2,998 bachelor's degrees. The university is classified among "R2: Doctoral Universities – High research spending and doctorate production".

Boise State University (BSU) is a public research university in Boise, Idaho, United States. Founded in 1932 by the Episcopal Church, it became an independent junior college in 1934 and has been awarding baccalaureate and master's degrees since 1965. It became a public institution in 1969. Boise State offers more than 100 graduate programs, including a variety of MBA programs and the MAcc program in the College of Business and Economics; master's and PhD programs in the Colleges of Engineering, Arts & Sciences, and Education; MPA program in the School of Public Service; and the MPH program in the College of Health Sciences. It is classified among "R2: Doctoral Universities – High research activity".

Construction aggregate, or simply aggregate, is a broad category of coarse to medium-grained particulate material used in construction. Traditionally, it includes natural materials such as sand, gravel, and crushed stone. As with other types of aggregates, it is a component of composite materials, particularly concrete and asphalt. Aggregates are the most mined materials in the world, being a significant part of the 6 billion tons of concrete produced per year. Aggregate serves as reinforcement to add strength to the resulting material. Due to the relatively high hydraulic conductivity as compared to most soil types, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and roadside edge drains. Aggregates are also used as base material under building foundations, roads and railroads (aggregate base). It has predictable, uniform properties, preventing differential settling under the road or building.

omponent of composite materials, particularly concrete and asphalt. Aggregates are the most mined materials in the world, being a significant part of the 6 billion tons of concrete produced per year. Aggregate serves as reinforcement to add strength to the resulting material. Due to the relatively high hydraulic conductivity as compared to most soil types, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and roadside edge drains. Aggregates are also used as base material under building foundations, roads and railroads (aggregate base). It has predictable, uniform properties, preventing differential settling under the road or building.

ion tons of concrete produced per year. Aggregate serves as reinforcement to add strength to the resulting material. Due to the relatively high hydraulic conductivity as compared to most soil types, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and roadside edge drains. Aggregates are also used as base material under building foundations, roads and railroads (aggregate base). It has predictable, uniform properties, preventing differential settling under the road or building.

The National Environmental Policy Act (NEPA) is a United States environmental law designed to promote the enhancement of the environment. It created new laws requiring U.S. federal government agencies to evaluate the environmental impacts of their actions and decisions, and it established the President's Council on Environmental Quality (CEQ). The act was passed by the U.S. Congress in December 1969 and signed into law by President Richard Nixon on January 1, 1970. More than 100 nations around the world have enacted national environmental policies modeled after NEPA. NEPA requires federal agencies to evaluate the environmental effects of their actions. NEPA's most significant outcome was the requirement that all executive federal agencies prepare environmental assessments (EAs) and environmental impact statements (EISs). These reports state the potential environmental effects of proposed federal agency actions. Further, U.S. Congress recognizes that each person has a responsibility to preserve and enhance the environment as trustees for succeeding generations. NEPA's procedural requirements do not apply to the president, Congress, or the federal courts since they are not a "federal agency" by definition.

Environmental Quality (CEQ). The act was passed by the U.S. Congress in December 1969 and signed into law by President Richard Nixon on January 1, 1970. More than 100 nations around the world have enacted national environmental policies modeled after NEPA. NEPA requires federal agencies to evaluate the environmental effects of their actions. NEPA's most significant outcome was the requirement that all executive federal agencies prepare environmental assessments (EAs) and environmental impact statements (EISs). These reports state the potential environmental effects of proposed federal agency actions. Further, U.S. Congress recognizes that each person has a responsibility to preserve and enhance the environment as trustees for succeeding generations. NEPA's procedural requirements do not apply to the president, Congress, or the federal courts since they are not a "federal agency" by definition.

January 1, 1970. More than 100 nations around the world have enacted national environmental policies modeled after NEPA. NEPA requires federal agencies to evaluate the environmental effects of their actions. NEPA's most significant outcome was the requirement that all executive federal agencies prepare environmental assessments (EAs) and environmental impact statements (EISs). These reports state the potential environmental effects of proposed federal agency actions. Further, U.S. Congress recognizes that each person has a responsibility to preserve and enhance the environment as trustees for succeeding generations. NEPA's procedural requirements do not apply to the president, Congress, or the federal courts since they are not a "federal agency" by definition.

The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the primary responsibilities of the states in addressing pollution and providing assistance to states to do so, including funding for publicly owned treatment works for the improvement of wastewater treatment; and maintaining the integrity of wetlands. The Clean Water Act was one of the first and most influential modern environmental laws in the United States. Its laws and regulations are primarily administered by the U.S. Environmental Protection Agency (EPA) in coordination with state governments, though some of its provisions, such as those involving filling or dredging, are administered by the U.S. Army Corps of Engineers. Its implementing regulations are codified at 40 C.F.R. Subchapters D, N, and O (Parts 100–140, 401–471, and 501–503). Technically, the name of the law is the Federal Water Pollution Control Act. The first FWPCA was enacted in 1948, but took on its modern form when completely rewritten in 1972 in an act entitled the Federal Water Pollution Control Act Amendments of 1972. Major changes have subsequently been introduced via amendatory legislation including the Clean Water Act of 1977 and the Water Quality Act (WQA) of 1987. The Clean Water Act does not directly address groundwater contamination.

d providing assistance to states to do so, including funding for publicly owned treatment works for the improvement of wastewater treatment; and maintaining the integrity of wetlands. The Clean Water Act was one of the first and most influential modern environmental laws in the United States. Its laws and regulations are primarily administered by the U.S. Environmental Protection Agency (EPA) in coordination with state governments, though some of its provisions, such as those involving filling or dredging, are administered by the U.S. Army Corps of Engineers. Its implementing regulations are codified at 40 C.F.R. Subchapters D, N, and O (Parts 100–140, 401–471, and 501–503). Technically, the name of the law is the Federal Water Pollution Control Act. The first FWPCA was enacted in 1948, but took on its modern form when completely rewritten in 1972 in an act entitled the Federal Water Pollution Control Act Amendments of 1972. Major changes have subsequently been introduced via amendatory legislation including the Clean Water Act of 1977 and the Water Quality Act (WQA) of 1987. The Clean Water Act does not directly address groundwater contamination.

ngineers. Its implementing regulations are codified at 40 C.F.R. Subchapters D, N, and O (Parts 100–140, 401–471, and 501–503). Technically, the name of the law is the Federal Water Pollution Control Act. The first FWPCA was enacted in 1948, but took on its modern form when completely rewritten in 1972 in an act entitled the Federal Water Pollution Control Act Amendments of 1972. Major changes have subsequently been introduced via amendatory legislation including the Clean Water Act of 1977 and the Water Quality Act (WQA) of 1987. The Clean Water Act does not directly address groundwater contamination.

he Copperbelt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. World production in 2016 was 116,000 tonnes (114,000 long tons; 128,000 short tons) according to Natural Resources Canada, and the DRC alone accounted for more than 50%. In 2024, production exceeded 300,000 tons, of which DRC accounted for more than 80%. Cobalt is primarily used in lithium-ion batteries, and in the manufacture of magnetic, wear-resistant and high-strength alloys. The compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes. Cobalt occurs naturally as only one stable isotope, cobalt-59. Cobalt-60 is a commercially important radioisotope, used as a radioactive tracer and for the production of high-energy gamma rays. Cobalt is also used in the petroleum industry as a catalyst when refining crude oil. This is to purge it of sulfur, which is very polluting when burned and causes acid rain. Cobalt is the active center of a group of coenzymes called cobalamins, also known as Vitamin B12, which is an essential vitamin for all animals.

Changes that Congo made to mining laws in 2002 attracted new investments in Congolese copper and cobalt projects. In 2005, the top producer of cobalt was the copper deposits in the Democratic Republic of the Congo's Katanga Province. Formerly Shaba province, the area had almost 40% of global reserves, reported the British Geological Survey in 2009. The Mukondo Mountain project, operated by the Central African Mining and Exploration Company (CAMEC) in Katanga Province, may be the richest cobalt reserve in the world. It produced an estimated one-third of the total global cobalt production in 2008. In July 2009, CAMEC announced a long-term agreement to deliver its entire annual production of cobalt concentrate from Mukondo Mountain to Zhejiang Galico Cobalt & Nickel Materials of China. In 2016, Chinese ownership of cobalt production in the Congo was estimated at over 10% of global cobalt supply, forming a key input to the Chinese cobalt refining industry and granting China substantial influence over the global cobalt supply chain. Chinese control of Congolese cobalt has raised concern in Western nations which have sought to reduce supply chain reliance upon China and have expressed concern regarding labor and human rights violations in cobalt mines in the DRC. Glencore's Mutanda Mine shipped 24,500 tons of cobalt in 2016, 40% of Congo DRC's output and nearly a quarter of global production. After oversupply, Glencore closed Mutanda for two years in late 2019. Glencore's Katanga Mining project is resuming as well and should produce 300,000 tons of copper and 20,000 tons of cobalt by 2019, according to Glencore. In February 2018, global asset management firm AllianceBernstein defined the DRC as economically "the Saudi Arabia of the electric vehicle age", due to its cobalt resources, as essential to the lithium-ion batteries that drive electric vehicles. On 9 March 2018, President Joseph Kabila updated the 2002 mining code, increasing royalty charges and declaring cobalt and coltan "strategic metals". The 2002 mining code was effectively updated on 4 December 2018. In February 2025, the DRC implemented a four-month suspension of cobalt exports, citing an oversupply of the metal amid a price decline to its lowest level in 21 years. Cobalt, a key byproduct of copper mining, is an essential material in battery technology. The DRC accounts for approximately 75 percent of the global supply. Within the country, the China Molybdenum Company (CMOC) dominates the industry, contributing roughly 40 percent of the world's cobalt production.

Artisanal mining supplied 17% to 40% of the DRC production as of 2016. Some 100,000 cobalt miners in Congo DRC use hand tools to dig hundreds of feet, with little planning and fewer safety measures, say workers and government and NGO officials, as well as The Washington Post reporters' observations on visits to isolated mines. The lack of safety precautions frequently causes injuries or death. Mining pollutes the vicinity and exposes local wildlife and indigenous communities to toxic metals thought to cause birth defects and breathing difficulties, according to health officials. Child labor is used in mining cobalt from African artisanal mines. Human rights activists have highlighted this and investigative journalism reporting has confirmed it. This revelation prompted cell phone maker Apple Inc., on 3 March 2017, to stop buying ore from suppliers such as Zhejiang Huayou Cobalt who source from artisanal mines in the DRC, and begin using only suppliers that are verified to meet its workplace standards. In 2023, Apple announced it would convert to using recycled cobalt by 2025. There is a push globally by the EU and major car manufacturers (OEM) for global production of cobalt to be sourced and –produced sustainably, responsibly and traceability of the supply chain. Mining companies are adopting and practising ESG initiatives in line with OECD Guidance and putting in place evidence of zero to low carbon footprint activities in the supply chain production of lithium-ion batteries. These initiatives are already taking place with major mining companies, artisanal and small-scale mining companies (ASM). Car manufacturers and battery manufacturer supply chains: Tesla, VW, BMW, BASF and Glencore are participating in several initiatives, such as the Responsible Cobalt Initiative and Cobalt for Development study. In 2018 BMW Group in partnership with BASF, Samsung SDI and Samsung Electronics have launched a pilot project in the DRC over one pilot mine, to improve conditions and address challenges for artisanal miners and the surrounding communities. The political and ethnic dynamics of the region have in the past caused outbreaks of violence and years of armed conflict and displaced populations. This instability affected the price of cobalt and also created perverse incentives for the combatants in the First and Second Congo Wars to prolong the fighting, since access to diamond mines and other valuable resources helped to finance their military goals—which frequently amounted to genocide—and also enriched the fighters themselves. While DR Congo has in the 2010s not recently been invaded by neighboring military forces, some of the richest mineral deposits adjoin areas where Tutsis and Hutus still frequently clash, unrest continues although on a smaller scale and refugees still flee outbreaks of violence. Cobalt extracted from small Congolese artisanal mining endeavors in 2007 supplied a single Chinese company, Congo DongFang International Mining. A subsidiary of Zhejiang Huayou Cobalt, one of the world's largest cobalt producers, Congo DongFang supplied cobalt to some of the world's largest battery manufacturers, who produced batteries for ubiquitous products like the Apple iPhones. Because of accused labour violations and environmental concerns, LG Chem subsequently audited Congo DongFang in accordance with OECD guidelines. LG Chem, which also produces battery materials for car companies, imposed a code of conduct on all suppliers that it inspects. In December 2019, International Rights Advocates, a human rights NGO, filed a landmark lawsuit against Apple, Tesla, Dell, Microsoft and Google company Alphabet for "knowingly benefiting from and aiding and abetting the cruel and brutal use of young children" in mining cobalt. The companies in question denied their involvement in child labour. In 2024 the court ruled that the suppliers facilitate force labor but the US tech companies are not liable because they don't operate as a shared enterprise with the suppliers and that the "alleged injuries are not fairly traceable" to any of the defendants' conduct. The book Cobalt Red alleges that workers including children suffer injuries, amputations, and death as the result of the hazardous working conditions and mine tunnel collapses during artisanal mining of cobalt in the DRC. Since child and slave labor have been repeatedly reported in cobalt mining, primarily in the artisanal mines of DR Congo, technology companies seeking an ethical supply chain have faced shortages of this raw material and the price of cobalt metal reached a nine-year high in October 2017, more than US$30 a pound, versus US$10 in late 2015. After oversupply, the price dropped to a more normal $15 in 2019. As a reaction to the issues with artisanal cobalt mining in DR Congo a number of cobalt suppliers and their customers have formed the Fair Cobalt Alliance (FCA) which aims to end the use of child labor and to improve the working conditions of cobalt mining and processing in the DR Congo.

nded over the years. In 2015, most REEs were being used for catalysts and magnets. The global move towards renewable energy technologies, such as electric vehicles (EVs) and wind turbines, along with advanced electronics, defence applications, and consumer electronics such as smartphones, has caused increased demand for REEs. REE extraction and processing can result in anthropogenic environmental enrichment. Effects of REE pollution on human and environmental health are still being explored. In recent years, there has been a sharp increase in published research on the health impacts as scholars call for more work to bridge gaps in available data. China dominates the rest of the world in terms of REE reserves and production; in 2019, it supplied around 90% of the global demand for the 17 rare-earth powders. The Chinese government has placed restrictions on its supply and sales of REEs since around 2010 for various reasons. After United States President Donald Trump escalated the trade war with China in 2025, China introduced further restrictions, leading other countries with known reserves to step up their exploration and production efforts. As of 2025, the US and Australia produce the second- and third-highest amounts of REEs, but Brazil has the second-largest reserves of the metals. A U.S. defense procurement restriction is scheduled to take effect in January 2027, prohibiting the use of Chinese-origin rare-earth metals and magnets in U.S.

India India has the third-largest reserves of rare-earths in the world, at 6.9 MT, including almost 35% of the world's sand mineral deposits, and has been stepping up the industry in the face of restrictions by China. The government-owned Indian Rare Earths is a major player. It was reported in parliament in July 2025 that The country has around 7.23 million tonnes (MT) of REOs contained in 13.15 MT monazite, found in coastal, inland, and riverine sands in the states of Andhra Pradesh, Odisha, Tamil Nadu, Kerala, West Bengal, Jharkhand, Gujarat, and Maharashtra, while another 1.29 MT rare earths are held in hard rocks in parts of Gujarat and Rajasthan. The Atomic Minerals Directorate for Exploration and Research is carrying out exploration in all terrains. The Geological Survey of India has been involved in 34 exploration projects. India exported around 18 tonnes of rare earth minerals between 2015 and 2025. However, India is lacking in advanced REE processing technology and skills, especially compared with China, the US, and Japan, so in 2025 the government launched its "National Critical Mineral Mission", with the aim of developing REE self-reliance.

In 2011, Australia produced 1,995 tonnes of rare earths. By 2021, it was the fourth largest producer of rare earths in the world, with a total production of 19,958 tonnes. As of August 2025 the largest Australian REE companies in terms of stocks are Lynas Corporation; Iluka Resources; Brazilian Rare Earths (whose 1,410 km2 (540 sq mi) of mining claims are in the state of Bahia, Brazil); Arafura Rare Earths; and Northern Minerals, whose main development is in Browns Range, Western Australia. Following the publication of its "Critical Minerals Strategy 2023–2030" in June 2023, in November 2024, the Albanese government announced its "International Partnerships in Critical Minerals" program, which will provide AU$40 million in grants across eight projects. The government's Critical Minerals Strategic Reserve plan is due for publication at the end of 2026. The intention of this plan is to introduce mechanisms such as a price floor that bring stability to the market and reduce price volatility. On 21 October 2025, the Prime Minister of Australia, Anthony Albanese, signed a deal with the President of the United States, Donald Trump, over rare-earths and other critical minerals that are needed for commercial clean energy production and technologically advanced military hardware. They each committed to provide at least US$1bn (A$1.54bn) towards a number of projects worth $US8.5bn (A$13bn) in both countries over six months.

owman, Centerville, Placerville, Pioneerville, Star Ranch, Crouch, Garden Valley, and Horseshoe Bend. Boise County is part of the Boise metropolitan area. Despite the name, Boise itself is in nearby Ada County. The Bogus Basin ski area is in the southwestern part of the county.

History The county was established on February 4, 1864, with its county seat at Idaho City. It was named for the Boise River, which was named by French-Canadian explorers and trappers for the great variety of trees growing along its banks in the lower desert valley. The county is one of four Idaho counties that also existed under Washington Territory. On January 12, 1863, The Washington territorial legislature established the county containing most of Idaho below 114° 30', excluding the territory lying west of the Payette River. They established its county seat at what later became Idaho City. The Boise Basin, which contains Idaho City, was one of the nation's richest gold mining districts; gold was discovered in 1862, and more of it was pulled from present-day Boise County than from the entire state of Alaska. At its peak in the mid-1860s, Idaho City was the largest city in the Northwest, and it was this rapid population influx that led to the establishment of the Idaho Territory in 1863. The lower–elevation communities of Horseshoe Bend (Payette River) and Boise (Boise River) were staging areas for the Boise Basin mines. The county's boundaries changed several times during Idaho's territorial period. Owyhee County (Idaho's oldest) and a portion of Oneida County were carved from the southern and eastern portion of the county as it existed under Washington Territory in late December 1863 and January 1864. When Idaho Territory established the county in February 1864, it contained all of present Ada, Canyon, and Payette counties. It also included most of present Boise and Gem Counties, the southern half of Washington County, and small portions of Adams, Custer, Owyhee, and Valley counties. When Ada County was created in December 1864, most of that territory was transferred to Ada County, leaving only small portions of Custer, Gem, Payette, Valley, and Washington counties together with most of present-day Boise County. The Boise River portion of the current western boundary was established by 1866. The southern boundary common to present Ada County was defined the following year. The northern boundary was most volatile Between 1873 and 1887 with the boundary shifting further north into Valley County, back south below Cascade, and then again north to include the North Fork of Payette River Basin. The county obtained its current boundary after Gem County was created in 1915 and Valley County in 1918. In March 2011, the county filed a Chapter 9 bankruptcy petition due to judgment against the county for violating the Fair Housing Act.

Major highways SH-21 - Ponderosa Pine Scenic Byway SH-52 SH-55 - Payette River Scenic Byway The county's two primary routes are scenic byways. Both are two-lane undivided highways for most of their length. The Ponderosa Pine Scenic Byway on State Highway 21 climbs northeast from Boise to Idaho City and Lowman, and ends at Stanley in Custer County, at the junction with State Highway 75. The Payette River Scenic Byway on State Highway 55 is a designated national scenic byway. It heads north from Eagle to Horseshoe Bend and climbs the whitewater of the Payette River to Cascade and McCall in Valley County, and ends at New Meadows in Adams County, at the junction with US Route 95. The closest thing to a traffic signal in Boise County is a flashing red light for Highway 52 where it meets Highway 55, in Horseshoe Bend.

The Idaho Batholith is a granitic and granodioritic batholith of Cretaceous-Paleogene age that covers approximately 25,000 square kilometres (9,700 sq mi) of central Idaho and adjacent Montana. The batholith has two lobes that are separate from each other geographically and geologically. The Bitterroot lobe is the smaller lobe and the larger lobe is the Atlanta lobe. The Bitterroot lobe is in the north and is separated from the larger Atlanta lobe in the south by the Belt Supergroup metamorphic rocks that compose the Salmon River Arch. Much of the Atlanta and Bitterroot lobes are in the Idaho Batholith ecoregion. The overall intrusive event that created the Idaho batholith lasted for around 55 million years from Late Cretaceous to the Eocene (98 to 43 Ma) of magmatism and includes the younger Challis suite which is not considered to be part of the Idaho Batholith. The Challis suite intruded both the Atlanta and Bitterroot lobes of the Idaho Batholith as well as the surrounding areas to the east of the Atlanta lobe.

orphic rocks that compose the Salmon River Arch. Much of the Atlanta and Bitterroot lobes are in the Idaho Batholith ecoregion. The overall intrusive event that created the Idaho batholith lasted for around 55 million years from Late Cretaceous to the Eocene (98 to 43 Ma) of magmatism and includes the younger Challis suite which is not considered to be part of the Idaho Batholith. The Challis suite intruded both the Atlanta and Bitterroot lobes of the Idaho Batholith as well as the surrounding areas to the east of the Atlanta lobe.

Idaho batholith lasted for around 55 million years from Late Cretaceous to the Eocene (98 to 43 Ma) of magmatism and includes the younger Challis suite which is not considered to be part of the Idaho Batholith. The Challis suite intruded both the Atlanta and Bitterroot lobes of the Idaho Batholith as well as the surrounding areas to the east of the Atlanta lobe.

ise, as well as part of the western Snake River Plain. The watershed encompasses approximately 4,100 square miles (11,000 km2) of highly diverse habitats, including alpine canyons, forest, rangeland, agricultural lands, and urban areas. Description The Boise River rises in three separate forks in the Sawtooth Range at elevations exceeding 10,000 feet (3,050 m), and is formed by the confluence of its North and Middle forks. The North Fork, 50 miles (80 km) long, rises in the Sawtooth Wilderness Area, along the Boise–Elmore county line, 60 miles (100 km) northeast of Boise. It flows generally southwest through the remote mountains in the Boise National Forest. The Middle Fork, approximately 52 miles (84 km) in length, rises within 12 miles (19 km) of the North Fork in the southern Sawtooth Wilderness Area in northeastern Elmore County. It flows west-southwest near the town of Atlanta, joining the North Fork to form the Boise River, approximately 15 miles (24 km) southeast of Idaho City.

History The river was called "Reed's River" in the early 19th century, named after Pacific Fur Company employee John Reed, who explored parts of the river throughout 1813 and 1814. The river is diverted to canals for irrigation on the plain west of what is now Boise. The dams that form the mountain reservoirs were constructed as part of the Bureau of Reclamation's "Boise Project" to provide agricultural irrigation, hydroelectricity, drinking water, and flood control to Boise and the Treasure Valley. The major projects' initial completion dates were: 1909 – Boise River Diversion Dam & New York Canal 1915 – Arrowrock Dam 1950 – Anderson Ranch Dam - (S. Fork) 1955 – Lucky Peak Dam - (U.S. Army Corps of Engineers) The Boise River was proposed for 50 years for a dam at Twin Springs, culminating in a 1966 Project Travois proposal, which would have used nuclear explosives to either create large amounts of rockfill aggregate for dam construction, or to induce a landslide that would have much the same effect. Project Travois was a component of Project Plowshare.

Recreation The river is a popular destination for floating, specifically on the Boise greenbelt. Tubers and floaters launch at Barber Park and land at Ann Morrison Park, between major irrigation diversion dams. Several minor diversion weirs are passed as well as several bridges on the 6-mile (10 km) trip. Water skiing is popular above the dam at the Lucky Peak Reservoir. On the lower (warmwater) course of the river, low summer flows and poorer water quality from agricultural runoff limit fishery production. This section of river supports a fair fishery for largemouth bass, smallmouth bass, and channel catfish. Upstream from Star, the river is a coldwater stream and supports a greater variety of fish. The most prevalent species on this section is mountain whitefish, as well as hatchery-reared rainbow trout, wild rainbow trout, and brown trout. Upstream from Lucky Peak and Arrowrock reservoirs, the river and its tributaries contain excellent populations of wild rainbow trout, mountain whitefish, and bull trout.

rs about a quarter of Idaho. Three major volcanic buttes dot the plain east of Arco, the largest being Big Southern Butte. Most of Idaho's major cities are in the Snake River Plain, as is much of its agricultural land. Geology The Snake River Plain can be divided into three sections: western, central, and eastern. The western Snake River Plain is a large tectonic graben or rift valley filled with several kilometers of Lake Idaho sediments; the sediments are underlain by rhyolite and basalt, and overlain by basalt. The western plain began to form around 11–12 Ma (million years ago) with the eruption of rhyolite lavas and ignimbrites. The western plain is not parallel to North American Plate motion and lies at a high angle to the central and eastern Snake River Plain.

The Snake River Plain is a geologic feature located primarily within the U.S. state of Idaho. It stretches about 400 miles (640 km) westward from northwest of the state of Wyoming to the Idaho-Oregon border. The plain is a wide, flat bow-shaped depression and covers about a quarter of Idaho.

The Snake River Plain can be divided into three sections: western, central, and eastern. The western Snake River Plain is a large tectonic graben or rift valley filled with several kilometers of Lake Idaho sediments; the sediments are underlain by rhyolite and basalt, and overlain by basalt. The western plain began to form around 11–12 Ma (million years ago) with the eruption of rhyolite lavas and ignimbrites. The western plain is not parallel to North American Plate motion and lies at a high angle to the central and eastern Snake River Plain.

The General Mining Act of 1872 is a United States federal law that authorizes and governs prospecting and mining for economic minerals, such as gold, platinum, and silver, on federal public lands. This law, approved on May 10, 1872, codified the informal system of acquiring and protecting mining claims on public land, formed by prospectors in California and Nevada from the late 1840s through the 1860s, such as during the California Gold Rush. All citizens of the United States of America 18 years or older have the right under the 1872 mining law to locate a lode (hard rock) or placer (gravel) mining claim on federal lands open to mineral entry. These claims may be located once a discovery of a locatable mineral is made.

Miners and prospectors in the California Gold Rush of 1849 found themselves in a legal vacuum. Although the US federal government had laws governing the leasing of mineral land, the United States had only recently acquired California by the Treaty of Guadalupe Hidalgo, and had little presence in the newly acquired territories. Miners organized their own governments in each new mining camp (for example the Great Republic of Rough and Ready), and adopted the Mexican mining laws then existing in California that gave the discoverer right to explore and mine gold and silver on public land. Miners moved from one camp to the next, and made the rules of all camps more or less the same, usually differing only in specifics such as in the maximum size of claims, and the frequency with which a claim had to be worked to avoid being forfeited and subject to being claimed by someone else. California miners spread the concept all over the west with each new mining rush, and the practices spread to all the states and territories west of the Great Plains. Mining legislation before 1872 Although the practices for open mining on public land were more-or-less universal in the West, and supported by state and territorial legislation, they were still illegal under existing federal law. At the end of the American Civil War, some eastern congressmen regarded western miners as squatters who were robbing the public patrimony, and proposed seizure of the western mines to pay the huge war debt. In June 1865, Representative George Washington Julian of Indiana introduced a bill for the government to take the western mines from their discoverers, and sell them at public auction. Representative Fernando Wood proposed that the government send an army to California, Colorado, and Arizona to expel the miners "by armed force if necessary to protect the rights of the Government in the mineral lands." He advocated that the federal government itself work the mines for the benefit of the treasury. Western representatives successfully argued that western miners and prospectors were performing valuable services by promoting commerce and settling new territory. In 1864, Congress passed a law that instructed courts deciding questions of contested mining rights to ignore federal ownership, and defer to the miners in actual possession of the ground. The following year, Congressional supporters of western miners tacked legislation legalizing lode (hardrock) mining on public land onto a law regarding ditch and canal rights in California, Oregon, and Nevada. The legislation, known as the "Chaffee laws" after Colorado Territorial representative Jerome B.

Mining legislation before 1872 Although the practices for open mining on public land were more-or-less universal in the West, and supported by state and territorial legislation, they were still illegal under existing federal law. At the end of the American Civil War, some eastern congressmen regarded western miners as squatters who were robbing the public patrimony, and proposed seizure of the western mines to pay the huge war debt. In June 1865, Representative George Washington Julian of Indiana introduced a bill for the government to take the western mines from their discoverers, and sell them at public auction. Representative Fernando Wood proposed that the government send an army to California, Colorado, and Arizona to expel the miners "by armed force if necessary to protect the rights of the Government in the mineral lands." He advocated that the federal government itself work the mines for the benefit of the treasury. Western representatives successfully argued that western miners and prospectors were performing valuable services by promoting commerce and settling new territory. In 1864, Congress passed a law that instructed courts deciding questions of contested mining rights to ignore federal ownership, and defer to the miners in actual possession of the ground. The following year, Congressional supporters of western miners tacked legislation legalizing lode (hardrock) mining on public land onto a law regarding ditch and canal rights in California, Oregon, and Nevada. The legislation, known as the "Chaffee laws" after Colorado Territorial representative Jerome B.

e United States Forest Service (USFS) is an agency within the United States Department of Agriculture. It administers the nation's 154 national forests and 20 national grasslands covering 193 million acres (780,000 km2) of land. The major divisions of the agency are the Chief's Office, National Forest System, State and Private Forestry, Business Operations, as well as Research and Development. The agency manages about 25% of federal lands and is the sole major national land management agency not part of the U.S. Department of the Interior (which manages the National Park Service, the U.S.

In 1876, Congress formed the office of Special Agent in the Department of Agriculture to assess the quality and conditions of forests in the United States. Franklin B. Hough was appointed the head of the office. In 1881, the office was expanded into the newly formed Division of Forestry. The Forest Reserve Act of 1891 authorized withdrawing land from the public domain as forest reserves managed by the Department of the Interior. In 1901, the Division of Forestry was renamed the Bureau of Forestry. The Transfer Act of 1905 transferred the management of forest reserves from the United States General Land Office of the Interior Department to the Bureau of Forestry, henceforth known as the United States Forest Service. Gifford Pinchot was the first United States chief forester in the presidency of Theodore Roosevelt. A historical note to include is that the National Park Service was created in 1916 to manage Yellowstone and several other parks; in 1956, the Fish and Wildlife Service became the manager of lands reserved for wildlife. The Grazing Service and the United States General Land Office were combined to create the Bureau of Land Management in 1946. Also of note was that it was not until 1976 that the Federal Land Policy and Management Act became the national policy for retaining public land for federal ownership. Significant federal legislation affecting the Forest Service includes the Weeks Act of 1911, the Taylor Grazing Act of 1934, P.L. 73-482; the Multiple Use – Sustained Yield Act of 1960, P.L. 86-517; the Wilderness Act, P.L. 88-577; the National Forest Management Act, P.L. 94-588; the National Environmental Policy Act, P.L. 91–190; the Cooperative Forestry Assistance Act, P.L. 95-313; and the Forest and Rangelands Renewable Resources Planning Act, P.L. 95-307. From the early 1900s to the present, there has been a fierce rivalry over control of forests between the Department of Agriculture and the Department of the Interior. Their roles overlap but numerous proposals to combine the two have failed. In 2009, the Government Accountability Office (GAO) evaluated whether the Forest Service should be moved from the Department of Agriculture to the Department of the Interior, which already manages some 438 million acres (1,770,000 km2) of public land through the National Park Service, the Fish and Wildlife Service, and the Bureau of Land Management. GAO ultimately did not offer a recommendation upon the conclusion of its performance audit. The Forest Service remains a part of the USDA. In March 2026, President Donald Trump announced his plans to move the Forest Service's headquarters from Washington D.C.

As of 2019, FY 2020 Forest Service total budget authority is $5.14 billion, a decrease of $815 million from 2019. The budget includes $2.4 billion for Wildland Fire Management, a decrease of $530 million from the 2019 Annualized Continuing Resolution because the "fire fix" cap adjustment becomes available in FY 2020, while the FY 2019 Annualized Continuing Resolution includes $500 million above the base as bridge to the first year of the fire fix. The Forest Service, headquartered in Washington, D.C., has 27,062 permanent, full-time employees as of Sept. 20, 2018, including 541 in the headquarters office and 26,521 in regional and field office. In March 2026, the Forest Service announced the move of its main office to Salt Lake City, Utah, as part of a restructuring plan so their leaders can be closer to the forests and the people they serve in the West. The Chief of the Forest Service is a career federal employee who oversees the agency. The Chief reports to the Under Secretary for Natural Resources and Environment in the U.S. Department of Agriculture, an appointee of the President confirmed by the Senate. The Chief's staff provides broad policy and direction for the agency, works with the Administration to develop a budget to submit to Congress, provides information to Congress on accomplishments, and monitors activities of the agency. There are five deputy chiefs for the following areas: National Forest System, State and Private Forestry, Research and Development, Business Operations, and Finance. The USDA Forest Service's mission is to sustain the health, diversity, and productivity of the Nation's forests and grasslands to meet the needs of present and future generations. Its motto is "Caring for the land and serving people." As the lead federal agency in natural resource conservation, the Forest Service provides leadership in the protection, management, and use of the nation's forest, rangeland, and aquatic ecosystems. The agency's ecosystem approach to management integrates ecological, economic, and social factors to maintain and enhance the quality of the environment to meet current and future needs. Through implementation of land and resource management plans, the agency ensures sustainable ecosystems by restoring and maintaining species diversity and ecological productivity that helps provide recreation, water, timber, minerals, fish, wildlife, wilderness, and aesthetic values for current and future generations of people. The everyday work of the Forest Service balances resource extraction, resource protection, and providing recreation. The work includes managing 193 million acres (780,000 km2) of national forest and grasslands, including 59 million acres (240,000 km2) of roadless areas; 14,077 recreation sites; 143,346 miles (230,693 km) of trails; 374,883 miles (603,316 km) of roads; and the harvesting of 1.5 billion trees per year. Further, the Forest Service fought fires on 2.996 million acres (12,120 km2) of land in 2007. The Forest Service organization includes ranger districts, national forests, regions, research stations and research work units and the Northeastern Area Office for State and Private Forestry.

ividual might become abundantly wealthy almost instantly, as expressed in the California Dream. Gold rushes helped spur waves of immigration that often led to the permanent settlement of new regions. Activities propelled by gold rushes define significant aspects of the culture of the Australian and North American frontiers. At a time when the world's money supply was based on gold, the newly-mined gold provided economic stimulus far beyond the goldfields, feeding into local and wider economic booms. The Gold Rush was a topic that inspired many TV shows and books considering it was a very important topic at the time.

ortant topic at the time. During various gold rushes, many books were published including The Call of the Wild, which had much success during the period. Gold rushes occurred as early as the times of ancient Greece, whose gold mining was described by Diodorus Siculus and Pliny the Elder. Surviving the gold rush Within each mining rush there is typically a transition through progressively higher capital expenditures, larger organizations, and more specialized knowledge. A rush typically begins with the discovery of placer gold made by an individual. At first the gold may be washed from the sand and gravel by individual miners with little training, using a gold pan or similar simple instrument. Once it is clear that the volume of gold-bearing sediment is larger than a few cubic metres, the placer miners will build rockers or sluice boxes, with which a small group can wash gold from the sediment many times faster than using gold pans. Winning the gold in this manner requires almost no capital investment, only a simple pan or equipment that may be built on the spot, and only simple organisation. The low investment, the high value per unit weight of gold, and the ability of gold dust and gold nuggets to serve as a medium of exchange, allow placer gold rushes to occur even in remote locations. After the sluice-box stage, placer mining may become increasingly large scale, requiring larger organisations and higher capital expenditures. Small claims owned and mined by individuals may need to be merged into larger tracts. Difficult-to-reach placer deposits may be mined by tunnels. Water may be diverted by dams and canals to placer mine active river beds or to deliver water needed to wash dry placers. The more advanced techniques of ground sluicing, hydraulic mining and dredging may be used. Typically the heyday of a placer gold rush would last only a few years. The free gold supply in stream beds would become depleted somewhat quickly, and the initial phase would be followed by prospecting for veins of lode gold that were the original source of the placer gold. Hard rock mining, like placer mining, may evolve from low capital investment and simple technology to progressively higher capital and technology. The surface outcrop of a gold-bearing vein may be oxidized, so that the gold occurs as native gold, and the ore needs only to be crushed and washed (free milling ore). The first miners may at first build a simple arrastra to crush their ore; later, they may build stamp mills to crush ore at greater speed. As the miners venture downwards, they may find that the deeper part of vein contains gold locked in sulfide or telluride minerals, which will require smelting. If the ore is still sufficiently rich, it may be worth shipping to a distant smelter (direct shipping ore). Lower-grade ore may require on-site treatment to either recover the gold or to produce a concentrate sufficiently rich for transport to the smelter. As the district turns to lower-grade ore, the mining may change from underground mining to large open-pit mining. Many silver rushes followed upon gold rushes. As transportation and infrastructure improve, the focus may change progressively from gold to silver to base metals. In this way, Leadville, Colorado started as a placer gold discovery, achieved fame as a silver-mining district, then relied on lead and zinc in its later days.

The resulting increase in the world's gold supply stimulated global trade and investment. Historians have written extensively about the mass migration, trade, colonization, and environmental history associated with gold rushes. Gold rushes were typically marked by a general buoyant feeling of a "free-for-all" in income mobility, in which any single individual might become abundantly wealthy almost instantly, as expressed in the California Dream. Gold rushes helped spur waves of immigration that often led to the permanent settlement of new regions. Activities propelled by gold rushes define significant aspects of the culture of the Australian and North American frontiers. At a time when the world's money supply was based on gold, the newly-mined gold provided economic stimulus far beyond the goldfields, feeding into local and wider economic booms. The Gold Rush was a topic that inspired many TV shows and books considering it was a very important topic at the time.

The Environmental Protection Agency (EPA) is an independent agency of the United States government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on December 2, 1970, after Nixon signed an executive order. The order establishing the EPA was ratified by committee hearings in the House and Senate. The agency is led by its administrator, who is appointed by the president and approved by the Senate. Since January 29, 2025, the administrator is Lee Zeldin. The EPA is not a Cabinet department, but the administrator is normally given cabinet rank. The EPA has its headquarters in Washington, D.C. There are regional offices for each of the agency's ten regions, as well as 27 laboratories around the country. The agency conducts environmental assessment, research, and education. It has the responsibility of maintaining and enforcing national standards under a variety of U.S. environmental laws, in consultation with state, tribal, and local governments. EPA enforcement powers include fines, sanctions, and other measures. It delegates some permitting, monitoring, and enforcement responsibility to U.S. states and the federally recognized tribes. The agency also works with industries and all levels of government in a wide variety of voluntary pollution prevention programs and energy conservation efforts. The agency's budgeted employee level in 2023 was 16,204.1 full-time equivalent (FTE).

r is Lee Zeldin. The EPA is not a Cabinet department, but the administrator is normally given cabinet rank. The EPA has its headquarters in Washington, D.C. There are regional offices for each of the agency's ten regions, as well as 27 laboratories around the country. The agency conducts environmental assessment, research, and education. It has the responsibility of maintaining and enforcing national standards under a variety of U.S. environmental laws, in consultation with state, tribal, and local governments. EPA enforcement powers include fines, sanctions, and other measures. It delegates some permitting, monitoring, and enforcement responsibility to U.S. states and the federally recognized tribes. The agency also works with industries and all levels of government in a wide variety of voluntary pollution prevention programs and energy conservation efforts. The agency's budgeted employee level in 2023 was 16,204.1 full-time equivalent (FTE).

or is normally given cabinet rank. The EPA has its headquarters in Washington, D.C. There are regional offices for each of the agency's ten regions, as well as 27 laboratories around the country. The agency conducts environmental assessment, research, and education. It has the responsibility of maintaining and enforcing national standards under a variety of U.S. environmental laws, in consultation with state, tribal, and local governments. EPA enforcement powers include fines, sanctions, and other measures. It delegates some permitting, monitoring, and enforcement responsibility to U.S. states and the federally recognized tribes. The agency also works with industries and all levels of government in a wide variety of voluntary pollution prevention programs and energy conservation efforts. The agency's budgeted employee level in 2023 was 16,204.1 full-time equivalent (FTE).

Boise (locally also ) is the capital and most populous city in the U.S. state of Idaho. It is the county seat of Ada County. The population of the city was 235,685 at the 2020 census. The Boise metropolitan area, located in the Treasure Valley, includes five counties of Idaho with an estimated population of 846,000, the most populous metropolitan area in Idaho and 95th-most populous in the United States. Located on the Boise River in southwestern Idaho, it is 41 miles (66 km) east of the Oregon border and 110 miles (177 km) north of the Nevada border. Downtown Boise's elevation is 2,704 feet (824 m) above sea level. Boise is home to major employers in the technology, manufacturing, and service sectors, including companies such as Micron Technology and Hewlett-Packard.

an area in Idaho and 95th-most populous in the United States. Located on the Boise River in southwestern Idaho, it is 41 miles (66 km) east of the Oregon border and 110 miles (177 km) north of the Nevada border. Downtown Boise's elevation is 2,704 feet (824 m) above sea level. Boise is home to major employers in the technology, manufacturing, and service sectors, including companies such as Micron Technology and Hewlett-Packard.

...that the military should continue killing Indians 'until the last Indian in the Territories was either on his reservation or enriched the sagebrush with his decaying carcass.' ...if the Indians refused to move there, 'they will be killed or put on the reservation by force, and certainly shot if they don't stay there.' Furthermore, the editor continues, 'The idea that the Indians have any right to the soil is ridiculous. ...They have no more rights to the soil of the Territories of the United States than wolves or coyotes...' This would be our plan of establishing friendship upon an eternal basis with our Indians: Let all the hostile bands of Idaho Territory be called in (they will not be caught in any other manner) to attend a grand treaty; plenty of blankets and nice little trinkets distributed among them; plenty of grub on hand; have a real jolly time with them; then just before the big feast put strychnine in their meat and poison to death the last mother's son of them. At the same time, native warriors around the valley, under the leadership of Howluck also known as "Bigfoot" among white settlers, among others, waged an escalating and intensified guerrilla campaign of harassment of passerby caravans along the Oregon Trail. The United States Army also escalated and intensified "punitive expeditions" against formations of warriors and against civilian communities as well. This marked the start of the "unofficial" Snake War in 1866. This war lasted until 1868, and is statistically the deadliest of the Indian Wars in the West in terms of casualties. In the end, 1,762 men were counted as the casualties of this war from both sides. In 1868, Fort Hall Indian Reservation was established in Southeastern Idaho, about 220 miles upstream, according to the terms of Fort Bridger Treaty. The Boise Valley Shoshone and Bannock Tribes were not party to this treaty. Nevertheless, in April 1869, the United States Military embarked on a campaign of "Removal, rounding up of natives in the region including in and around Boise, and expelling them with cavalry escort to Fort Hall Indian Reservation. This period is known among the Shoshone and Bannock people as Idaho's Trail of Tears. Some of the natives managed to escape, and they ran to either Duck Valley or Fort McDermitt in Nevada. Incorporation and growth Boise's early growth was significantly driven by its role in supplying the nearby gold towns that sprung up in the 1860s northeast and then southwest of the town. Miners sometimes wintered in Boise and a number of early prominent businessmen were miners who settled in town in the years after the gold rush waned. By 1864 substantial agricultural production was underway on easily irrigated lands near the river and three canal companies had been incorporated. Early transportation improvements were largely a result of toll road franchises awarded by the territorial legislature starting in the 1860s. These first ran from Fort Boise to the mining centers in the Boise Basin and east to Rocky Bar and to Rattlesnake Station where they connected to the Oregon Trail. Territorial census records from a special 1864 enumeration list the population of Boise as 1,658, and an act of December 12, 1864, was the first attempt by the Idaho Territorial Legislature to incorporate the city. This was rejected by voters the following March. Two more unsuccessful attempts were made to organize a city administration by election before the 1866 version of the city charter was approved by voters on January 6, 1868. The growing number of homes and businesses, for which owners wanted proper legal title, may have contributed to the eventual success of incorporation. All of these rejected efforts to incorporate the city came after Boise had been controversially made the state capital in 1864 over strong opposition from northern Idaho interests. This decision reflected the rapid shift of population growth from north to south after the discovery of gold in southern Idaho. By 1868 Boise had over 400 permanent buildings with a wide range of commercial services. 1868 also marked the formal beginning of a long advocacy for railroad connections to other Idaho communities and, just as importantly, to other growing cities in the west such as Portland, Oregon. Competing railroad and western state government interests frustrated these efforts for many years. Designed by Alfred B. Mullett, the U.S. Assay Office at 210 Main Street was built in 1871 and today is a National Historic Landmark. It first began accepting gold and silver for purchase on March 2, 1872, largely eliminating the need to transport ore to the mint in San Francisco. A territorial penitentiary, now known as the Old Idaho State Penitentiary, opened the same month several miles east of town. Mining continued to be important to Boise's economic growth and periodic booms contributed to population growth as well, though production of gold and silver probably peaked in the 1860s. 1882's gold and silver production of $3,500,000 declined to $1,488,315 (including lead) by 1899. Boise began to earn its City of Trees nickname in this period with a popular focus on a range of tree planting projects. Thomas J. Davis planted several thousand fruit trees in 1864 and several other early businessmen either founded nurseries or orchards of their own. In the 1870s tree planting began in earnest in downtown Boise led by prominent hotels as well as businessmen and residents. In 1907 Davis donated 43 acres of his orchard property to the city for use as a park in the name of his wife Julia. Commercial agriculture continued to expand, but was slowed by the lack of reliable rail links to regional and national markets and by a lack of large scale irrigation projects, which themselves were often tied to hoped-for railroad projects for financing. A.D. Foote, a successful mining engineer, drew up plans to irrigate up to 500,000 acres immediately south of Boise in 1882, but progress was halting and smaller farms were the norm until after the turn of the century with most located near to the river bottom where soil was productive and irrigation more easily achieved. Fruit orchards proliferated and sugar beets, still an important agricultural industry in Idaho, began to be widely cultivated in the 1890s. Cattle and sheep farming became increasingly important as the century closed. With the exception of dairy, most livestock products were exported from Idaho, unlike other agricultural products which were still largely scaled to support local markets. The timber industry also increasingly thrived in the Boise market in the 1880s and 1890s. Large quantities of timber were exported from elsewhere in Idaho, but a growing Boise supported the expansion of Alexander Rossi's sawmill, first established in 1865. Prominent early Boisean William Ridenbaugh had inherited control of the canal now bearing his name from his uncle William Morris in 1878 and later partnered with Rossi to expand the sawmill capacity under the name Rossi and Ridenbaugh Lumber Company. Their materials supported bridge building and the rapid expansion of Boise in the 1890s. As with many early infrastructure ventures, electrification succeeded only after at least one false start. July 4, 1887, marked the start of electrical transmission from a plant located on the Bench. William Ridenbaugh provided expertise and manpower for the water supply and several months were spent rigging poles and lines from the Bench to the service area across the river. Additional electrical supplies allowed the building of an electric streetcar line in 1891. This ran without interruption until buses replaced the lines in 1927, tracking—and sometimes driving—the development of Boise and nearby communities. This system expanded over several decades, reaching into the North End, South Boise and across the river on Front St. A loop line, completed in 1912, ran as far as Caldwell and Nampa, providing transport throughout the valley. Three early trolley companies merged in 1912 to form the Idaho Traction Company with a depot at 7th and Bannock Streets downtown. Additional services and urban amenities arrived in the 1890s as Boise grew. Exploratory drilling for hot water was successful in 1890 and by the end of the decade many homes along Warm Springs avenue were being heated by this source. A natatorium was built in 1892 close to the source of the hot water near the Idaho State Penitentiary. Churches serving several denominations, a Jewish synagogue, a major hardware store and department store, a Masonic hall, the Columbia Theater, Saint Alphonsus' Hospital, a number of parochial and secular schools, a City Hall and a new Union Pacific passenger station, constructed when service was finally extended to downtown, were all built during the 1890s. Falk's Department Store sponsored a semi-professional baseball team representing Boise from at least 1892 and the city supported other organized sports as they became popular.

at extracts rock or minerals from the earth. Open-pit mines are used when deposits of commercially useful ore or rocks are found near the surface where the overburden is relatively thin.

Miners typically drill a series of test holes to locate an underground ore body. From the extracted samples, they can determine the extent of the ore. This helps them determine the likely location of the veins or benches of ore and its commercial value. Open-pit mines that produce building materials and dimension stone are commonly referred to as quarries. Open-cast mines are dug on benches, which describe vertical levels of the hole. The interval of the benches depends on the deposit being mined, the mineral being mined, and the size of the machinery that is being used. Generally, large mine benches are 12 to 15 metres thick. In contrast, many quarries do not use benches, as they are usually shallow. Mining can be conducted on more than one bench at a time, and access to different benches is done with a system of ramps. The width of each bench is determined by the size of the equipment being used, generally 20–40 metres wide. Downward ramps are created to allow mining on a new level to begin. This new level will become progressively wider to form the new pit bottom. Most walls of the pit are generally mined on an angle less than vertical. Waste rock is stripped when the pit becomes deeper, therefore this angle is a safety precaution to prevent and minimize damage and danger from rock falls. However, this depends on how weathered and eroded the rocks are, and the type of rocks involved. It also depends on the amount of structural weaknesses that occur within the rocks, such as faults, shears, joints or foliations. The walls are stepped. The inclined section of the wall is known as the batter, and the flat part of the step is known as the bench or berm. The steps in the walls help prevent rock falls continuing down the entire face of the wall. In some instances additional ground support is required and rock bolts, cable bolts and shotcrete are used.

See also Artisanal mining – Independent, small-scale, subsistence mining Closure problem – Computational problem in graph theory applied to open-pit mines for optimal extraction (not related to closing the mine) Cut (earthmoving) – Location where earth is removed to make way for a road, railway, or canalPages displaying short descriptions of redirect targets List of open-pit mines Trench – Excavated channel in ground Tunneling – Underground passage made for traffic

Source is required because metal must come from somewhere, and be liberated by some process. Transport is required first to move the metal-bearing fluids or solid minerals into their current position, and refers to the act of physically moving the metal, as well as to chemical or physical phenomena which encourage movement. Trapping is required to concentrate the metal via some physical, chemical, geological, or biological mechanism into a concentration which forms mineable ore. The biggest deposits form when the source is large, the transport mechanism is efficient, and the trap is active and ready at the right time.

Magmatic processes Fractional crystallization: separates ore and non-ore minerals according to their crystallization temperature. As early crystallizing minerals form from magma, they incorporate certain elements, some of which are metals. These crystals may settle onto the bottom of the intrusion, concentrating ore minerals there. Chromite and magnetite are ore minerals that form in this way. Liquid immiscibility: sulfide ores containing copper, nickel, or platinum may form from this process. As a magma changes, parts of it may separate from the main body of magma. Two liquids that will not mix are called immiscible; oil and water are an example. In magmas, sulfides may separate and sink below the silicate-rich part of the intrusion or be injected into the rock surrounding it. These deposits are found in mafic and ultramafic rocks. Hydrothermal processes These processes are the physicochemical phenomena and reactions caused by movement of hydrothermal water within the crust, often as a consequence of magmatic intrusion or tectonic upheavals. The foundations of hydrothermal processes are the source-transport-trap mechanism. Sources of hydrothermal solutions include seawater and meteoric water circulating through fractured rock, formational brines (water trapped within sediments at deposition), and metamorphic fluids created by dehydration of hydrous minerals during metamorphism. Metal sources may include a plethora of rocks. However most metals of economic importance are carried as trace elements within rock-forming minerals, and so may be liberated by hydrothermal processes.

Hydrothermal processes These processes are the physicochemical phenomena and reactions caused by movement of hydrothermal water within the crust, often as a consequence of magmatic intrusion or tectonic upheavals. The foundations of hydrothermal processes are the source-transport-trap mechanism. Sources of hydrothermal solutions include seawater and meteoric water circulating through fractured rock, formational brines (water trapped within sediments at deposition), and metamorphic fluids created by dehydration of hydrous minerals during metamorphism. Metal sources may include a plethora of rocks. However most metals of economic importance are carried as trace elements within rock-forming minerals, and so may be liberated by hydrothermal processes.

The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the United States Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March 3, 1879, to study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The agency also makes maps of planets and moons, based on data from U.S. space probes. The sole scientific agency of the U.S. Department of the Interior, USGS is a fact-finding research organization with no regulatory responsibility. It is headquartered in Reston, Virginia, with major offices near Lakewood, Colorado; at the Denver Federal Center; and in NASA Research Park in California. In 2009, it employed about 8,670 people. The current motto of the USGS, in use since August 1997, is "science for a changing world".

scape of the United States, its natural resources, and the natural hazards that threaten it. The agency also makes maps of planets and moons, based on data from U.S. space probes. The sole scientific agency of the U.S. Department of the Interior, USGS is a fact-finding research organization with no regulatory responsibility. It is headquartered in Reston, Virginia, with major offices near Lakewood, Colorado; at the Denver Federal Center; and in NASA Research Park in California. In 2009, it employed about 8,670 people. The current motto of the USGS, in use since August 1997, is "science for a changing world".

enver Federal Center; and in NASA Research Park in California. In 2009, it employed about 8,670 people. The current motto of the USGS, in use since August 1997, is "science for a changing world". The agency's previous slogan, adopted on its hundredth anniversary, was "Earth Science in the Public Service". History Prior Surveys In the early-1800s, geological surveys were conducted by states and private individuals to support agriculture as a result of westward migration after the War of 1812. The first Federal survey was conducted in 1834 by George William Featherstonhaugh under the Topographical Bureau of the U.S. Army Corps of Engineers to create a geological map of the United States. This was followed by other geological explorations like the United States Exploring Expedition and the establishment of the Corps of Topographical Engineers led by John James Abert. As minerals like gold were being discovered in the west, land surveys became necessary as part of Manifest destiny. As a result, various states set up geological survey institutions in the mid-1800s, e.g., the Kentucky Geological Survey, established in 1854. On March 2, 1867, Congress authorized explorations focused on the geology along the Transcontinental railroad under the U.S. Army Corps of Engineers led by Clarence King and a survey of the natural resources of Nebraska under the General Land Office led by Ferdinand Vandeveer Hayden. The explorations led to the creation of the United States Geological and Geographical Survey of the Territories which included surveys led by John Wesley Powell (Powell Geographic Expedition of 1869) and George Wheeler (Wheeler Survey).

state 84, and 6 miles (9.7 km) west of Meridian. It is the second principal city of the Boise metropolitan area. The name "Nampa" may have come from a Shoshoni word meaning 'moccasin' or 'footprint'. According to toponymist William O. Bright, the name comes from the Shoshoni word /nampai/, meaning "foot".

W. J. McClelland, c.1901–1903 Frank H. Sutherland, c.1903–1904 H. A. Partridge, c.1904–1905, 1907–1908, 1913–1914 Rudolphus W. Purdum, c.1905–1906 E. H. Dewey, c.1909–1911 T. E. Munhall, c.1915–1917 Robert A. Davis, c.1917–1919 H. H. Keim, c.1919–1920 J. Fremont Bow, 1921–1923 Eugene Emerson, c.1923–1925 George Meffan, 1925–1929 Eustace Smallwood, c.1929–1930 E. W. Rising, c.1933–1935 George I. Van Name, 1935–1937 R. Lewis Ord, 1937–1939 Ben H. Waigand, 1939–1943 A. E. Lindsey, c.1943–1945 Sevren G. Honstead, 1945–1947 Peter Johnson, 1947–1951 Preston Capell, c.1951–1957 Thomas Leupp, 1957–1961 Ernest Starr, 1961–1981 Winston K.

pa ( ) is the most populous city in Canyon County, Idaho, United States. The population was 100,200 at the 2020 census. It is Idaho's third-most populous city. Nampa is about 20 miles (32 km) west of Boise along Interstate 84, and 6 miles (9.7 km) west of Meridian. It is the second principal city of the Boise metropolitan area. The name "Nampa" may have come from a Shoshoni word meaning 'moccasin' or 'footprint'. According to toponymist William O. Bright, the name comes from the Shoshoni word /nampai/, meaning "foot".

contains slightly more than half of the Duck Valley Indian Reservation, which extends over the Nevada border, into Elko County. The majority of the federally recognized Shoshone-Paiute Tribe that is associated with this reservation lives on the Nevada side; its tribal center is in Owyhee, Nevada. History This area was the territory of Western Shoshone, Northern Paiute, and Bannock peoples and their ancestors for thousands of years prior to the arrival of European settlers. Settler interests in securing land and resources spurred conflict and led to the indigenous peoples being forced onto reservations. On December 31, 1863, Owyhee County became the first county organized by the Idaho Territory Legislature. While Boise, Idaho, Nez Perce, and Shoshone counties were organized under the laws of Washington Territory, they were not recognized by the Idaho Territory until February 1864. The original county seat at Ruby City was moved to nearby Silver City in 1867. Owyhee County's original boundary was the portion of Idaho Territory south of the Snake River and west of the Rocky Mountains. Less than a month after the creation of Owyhee County, Oneida County was formed in January 1864 from the eastern portion of the county. The formation of Cassia County in 1879 took further territory in the east. Owyhee County's history is closely linked to the mining boom that dominated Idaho Territory in the second half of the 19th century. Silver City and Ruby City developed as boom towns. At its height in the 1880s, Owyhee County was among the most populous places in Idaho. Today it is among the least populous, at 1.4 persons per square mile (0.54 persons/km2). Because of pressure from miners and settlers, the federal government made a treaty in 1877 with the Western Shoshone to cede land, and established what is now known as the Duck Valley Indian Reservation in this county and across the border in Elko County, Nevada. The reservation was expanded in 1886 to accommodate people of the Northern Paiute. In the 20th century, the tribes combined and are federally recognized as a single government; the majority of the people live on the Nevada side of the reservation. There were two railroad lines extending into Owyhee County, the first was the Boise Nampa & Owyhee Railroad which built starting in 1896 from Nampa, Idaho south towards Melba, Idaho and eventually across the Snake River into Owyhee County in 1897, whereupon it crossed Rabbit Creek before arriving in Murphy, Idaho. The first train into Murphy occurred in 1899. The Boise, Nampa & Owyhee Railroad was acquired by the Idaho Northern Railroad in 1907; the line was taken over by the Oregon Short Line Railroad in 1913 following their purchase of the Idaho Northern Railroad, after which it became known as the Murphy Branch line. Daily passenger service to Murphy was discontinued in 1942. By 1947, shipping animals out of Murphy was no longer profitable for the railroad. The Murphy portion of the line was abandoned in 1947. In the 1950s, trucks and highways became the dominant mode of transportation. The last train left Melba in 1994, and all rails were torn out in that same year. The second railroad line was the Oregon Shortline Railroad which built south from Nyssa Oregon beginning in 1911, passing through Adrian Oregon the line ended after 25 miles in Homedale Idaho, in 1922 it was extended Marsing Idaho to accommodate additional agricultural traffic. In 1970, the Marsing and Homedale depots were closed by Union Pacific. In 1987, with declining carload, Union Pacific offered the line for sale but no buyers were found. Following the closure of the lumber mill in Homedale in the early 1990s, the Homedale branch (now reduced to the status of an "industrial lead") generated a total of 49 carloads in 1995 and 42 in 1996. In 1997, Union Pacific filed for permission to abandon the Idaho portion of the line and received no formal protest, the tracks were ripped up the following year. Owyhee County gained its present boundaries in 1930 after an election approved moving a portion of it near Glenns Ferry and King Hill to neighboring Elmore County. In 1934, the county seat was moved from the nearly abandoned Silver City to its present location in Murphy.

020 census, the population was 11,913. The county seat is Murphy, and its largest city is Homedale. In area it is the second-largest county in Idaho, behind Idaho County. Owyhee County is part of the Boise metropolitan area and contains slightly more than half of the Duck Valley Indian Reservation, which extends over the Nevada border, into Elko County.

History This area was the territory of Western Shoshone, Northern Paiute, and Bannock peoples and their ancestors for thousands of years prior to the arrival of European settlers. Settler interests in securing land and resources spurred conflict and led to the indigenous peoples being forced onto reservations. On December 31, 1863, Owyhee County became the first county organized by the Idaho Territory Legislature. While Boise, Idaho, Nez Perce, and Shoshone counties were organized under the laws of Washington Territory, they were not recognized by the Idaho Territory until February 1864. The original county seat at Ruby City was moved to nearby Silver City in 1867. Owyhee County's original boundary was the portion of Idaho Territory south of the Snake River and west of the Rocky Mountains. Less than a month after the creation of Owyhee County, Oneida County was formed in January 1864 from the eastern portion of the county. The formation of Cassia County in 1879 took further territory in the east. Owyhee County's history is closely linked to the mining boom that dominated Idaho Territory in the second half of the 19th century. Silver City and Ruby City developed as boom towns. At its height in the 1880s, Owyhee County was among the most populous places in Idaho. Today it is among the least populous, at 1.4 persons per square mile (0.54 persons/km2). Because of pressure from miners and settlers, the federal government made a treaty in 1877 with the Western Shoshone to cede land, and established what is now known as the Duck Valley Indian Reservation in this county and across the border in Elko County, Nevada. The reservation was expanded in 1886 to accommodate people of the Northern Paiute. In the 20th century, the tribes combined and are federally recognized as a single government; the majority of the people live on the Nevada side of the reservation. There were two railroad lines extending into Owyhee County, the first was the Boise Nampa & Owyhee Railroad which built starting in 1896 from Nampa, Idaho south towards Melba, Idaho and eventually across the Snake River into Owyhee County in 1897, whereupon it crossed Rabbit Creek before arriving in Murphy, Idaho. The first train into Murphy occurred in 1899. The Boise, Nampa & Owyhee Railroad was acquired by the Idaho Northern Railroad in 1907; the line was taken over by the Oregon Short Line Railroad in 1913 following their purchase of the Idaho Northern Railroad, after which it became known as the Murphy Branch line. Daily passenger service to Murphy was discontinued in 1942. By 1947, shipping animals out of Murphy was no longer profitable for the railroad. The Murphy portion of the line was abandoned in 1947. In the 1950s, trucks and highways became the dominant mode of transportation. The last train left Melba in 1994, and all rails were torn out in that same year. The second railroad line was the Oregon Shortline Railroad which built south from Nyssa Oregon beginning in 1911, passing through Adrian Oregon the line ended after 25 miles in Homedale Idaho, in 1922 it was extended Marsing Idaho to accommodate additional agricultural traffic. In 1970, the Marsing and Homedale depots were closed by Union Pacific. In 1987, with declining carload, Union Pacific offered the line for sale but no buyers were found. Following the closure of the lumber mill in Homedale in the early 1990s, the Homedale branch (now reduced to the status of an "industrial lead") generated a total of 49 carloads in 1995 and 42 in 1996. In 1997, Union Pacific filed for permission to abandon the Idaho portion of the line and received no formal protest, the tracks were ripped up the following year. Owyhee County gained its present boundaries in 1930 after an election approved moving a portion of it near Glenns Ferry and King Hill to neighboring Elmore County. In 1934, the county seat was moved from the nearly abandoned Silver City to its present location in Murphy.

The Resource Conservation and Recovery Act (RCRA), enacted in 1976, is the primary federal law in the United States governing the disposal of solid waste and hazardous waste. History and goals Congress enacted RCRA to address the increasing problems the nation faced from its growing volume of municipal and industrial waste. RCRA was an amendment of the Solid Waste Disposal Act of 1965.

Implementation The EPA publishes waste management regulations, which are codified in Title 40 of the Code of Federal Regulations in parts 239 through 282. Regulations regarding management of hazardous waste begin in part 260.

Subtitle F: Federal responsibilities Application of Federal, State and Local Law to Federal Facilities Federal procurement Cooperation with EPA; Applicability of solid waste disposal guidelines to executive agencies Subtitle G: Miscellaneous provisions Whistleblower protection.

city in Idaho. As of the 2020 census, Caldwell had a population of 59,996. Caldwell is considered part of the Boise metropolitan area, and is the location of the College of Idaho. The city is located approximately 24 miles (39 km) west of Boise, and approximately 17 miles (27 km) east of the Oregon border. History The present-day location of Caldwell is along a natural passageway to the Inland and Pacific Northwest. Native American tribes from the west coast, north Idaho and as far away as Colorado came to the banks of the Boise River for annual trading fairs, or rendezvous. European and some Hawaiian explorers and traders soon followed the paths left by Native Americans and hopeful emigrants later forged the Oregon Trail and followed those paths to seek a better life in the Oregon Territory. Pioneers of the Trail traveled along the Boise River to Canyon Hill and forded the river close to the Silver Bridge on Plymouth Street. During the Civil War, the discovery of gold in Idaho's mountains brought a variety of new settlers into the area. Many never made it to the mines but settled along the Boise River and run ferries, stage stations, and freighting businesses. These early entrepreneurs created small ranches and farms in the river valleys. Caldwell's inception occurred largely as a result of the construction of the Oregon Short Line Railroad, which connected Wyoming to Oregon through Idaho. Robert E. Strahorn came to the Boise River Valley in 1883 to select a route for the railroad. He rejected the grade into Boise City as too steep and chose a site 30 miles to the west. He drove a stake into an alkali flat of sagebrush and greasewood and the City of Caldwell was platted. Caldwell was named after one of Strahorn's business partners, Alexander Caldwell, a former senator from Kansas. When Caldwell was platted in August 1883, its founder, the Idaho and Oregon Land Improvement Company, started persuading settlers and businessmen to move to the area. Within four months, Caldwell had 600 residents living in 150 dwellings, 40 businesses, a school, a telephone exchange, and two newspapers. On January 15, 1890, the Board of Commissioners of Ada County issued a handwritten order incorporating the City of Caldwell. The College of Idaho was founded in Caldwell in 1891. In 1892, Canyon County was established from a portion of Ada County, and Caldwell was named the county seat. Irrigation canals and waterways were constructed throughout Canyon County, providing the foundation for an agricultural economy. The Oregon Short Line Railroad became part of the larger Union Pacific Railroad network and in 1906 the Caldwell freight and passenger depot was constructed. Caldwell experienced moderate growth as an agricultural processing, commercial retail and educational center during the 20th century. In 2009, the City of Caldwell completed a revitalization project to restore Indian Creek, which runs through downtown Caldwell, but had been used for sewage disposal by local industries and been covered over.

History The present-day location of Caldwell is along a natural passageway to the Inland and Pacific Northwest. Native American tribes from the west coast, north Idaho and as far away as Colorado came to the banks of the Boise River for annual trading fairs, or rendezvous. European and some Hawaiian explorers and traders soon followed the paths left by Native Americans and hopeful emigrants later forged the Oregon Trail and followed those paths to seek a better life in the Oregon Territory. Pioneers of the Trail traveled along the Boise River to Canyon Hill and forded the river close to the Silver Bridge on Plymouth Street. During the Civil War, the discovery of gold in Idaho's mountains brought a variety of new settlers into the area. Many never made it to the mines but settled along the Boise River and run ferries, stage stations, and freighting businesses. These early entrepreneurs created small ranches and farms in the river valleys. Caldwell's inception occurred largely as a result of the construction of the Oregon Short Line Railroad, which connected Wyoming to Oregon through Idaho. Robert E. Strahorn came to the Boise River Valley in 1883 to select a route for the railroad. He rejected the grade into Boise City as too steep and chose a site 30 miles to the west. He drove a stake into an alkali flat of sagebrush and greasewood and the City of Caldwell was platted. Caldwell was named after one of Strahorn's business partners, Alexander Caldwell, a former senator from Kansas. When Caldwell was platted in August 1883, its founder, the Idaho and Oregon Land Improvement Company, started persuading settlers and businessmen to move to the area. Within four months, Caldwell had 600 residents living in 150 dwellings, 40 businesses, a school, a telephone exchange, and two newspapers. On January 15, 1890, the Board of Commissioners of Ada County issued a handwritten order incorporating the City of Caldwell. The College of Idaho was founded in Caldwell in 1891. In 1892, Canyon County was established from a portion of Ada County, and Caldwell was named the county seat. Irrigation canals and waterways were constructed throughout Canyon County, providing the foundation for an agricultural economy. The Oregon Short Line Railroad became part of the larger Union Pacific Railroad network and in 1906 the Caldwell freight and passenger depot was constructed. Caldwell experienced moderate growth as an agricultural processing, commercial retail and educational center during the 20th century. In 2009, the City of Caldwell completed a revitalization project to restore Indian Creek, which runs through downtown Caldwell, but had been used for sewage disposal by local industries and been covered over.

location of the College of Idaho. The city is located approximately 24 miles (39 km) west of Boise, and approximately 17 miles (27 km) east of the Oregon border. History The present-day location of Caldwell is along a natural passageway to the Inland and Pacific Northwest. Native American tribes from the west coast, north Idaho and as far away as Colorado came to the banks of the Boise River for annual trading fairs, or rendezvous. European and some Hawaiian explorers and traders soon followed the paths left by Native Americans and hopeful emigrants later forged the Oregon Trail and followed those paths to seek a better life in the Oregon Territory. Pioneers of the Trail traveled along the Boise River to Canyon Hill and forded the river close to the Silver Bridge on Plymouth Street. During the Civil War, the discovery of gold in Idaho's mountains brought a variety of new settlers into the area. Many never made it to the mines but settled along the Boise River and run ferries, stage stations, and freighting businesses. These early entrepreneurs created small ranches and farms in the river valleys. Caldwell's inception occurred largely as a result of the construction of the Oregon Short Line Railroad, which connected Wyoming to Oregon through Idaho. Robert E. Strahorn came to the Boise River Valley in 1883 to select a route for the railroad. He rejected the grade into Boise City as too steep and chose a site 30 miles to the west. He drove a stake into an alkali flat of sagebrush and greasewood and the City of Caldwell was platted. Caldwell was named after one of Strahorn's business partners, Alexander Caldwell, a former senator from Kansas. When Caldwell was platted in August 1883, its founder, the Idaho and Oregon Land Improvement Company, started persuading settlers and businessmen to move to the area. Within four months, Caldwell had 600 residents living in 150 dwellings, 40 businesses, a school, a telephone exchange, and two newspapers. On January 15, 1890, the Board of Commissioners of Ada County issued a handwritten order incorporating the City of Caldwell. The College of Idaho was founded in Caldwell in 1891. In 1892, Canyon County was established from a portion of Ada County, and Caldwell was named the county seat. Irrigation canals and waterways were constructed throughout Canyon County, providing the foundation for an agricultural economy. The Oregon Short Line Railroad became part of the larger Union Pacific Railroad network and in 1906 the Caldwell freight and passenger depot was constructed. Caldwell experienced moderate growth as an agricultural processing, commercial retail and educational center during the 20th century. In 2009, the City of Caldwell completed a revitalization project to restore Indian Creek, which runs through downtown Caldwell, but had been used for sewage disposal by local industries and been covered over.

105, which by 2025 was estimated to have risen to 275,123, making it the second-most populous county in Idaho. The county seat is Caldwell, and its largest city is Nampa. Canyon County is part of the Boise metropolitan area. History Hudson's Bay Company established Fort Boise in 1834 near what is now Parma, but abandoned it in 1855. Emigrants traveled through Canyon County on the Oregon Trail. Discovery of gold in the Boise Basin in 1862 brought settlement to the region again. The lower Boise River was fully contained within Boise County from 1863 until the formation of Ada County in 1864. Settlement of the lower Boise River west of Boise City was limited prior to the completion of the Oregon Short Line Railroad. Middleton was the first European settlement of Canyon County, starting in 1863. The 1870 Census for Ada County listed 76 residents of the Boise Valley, excluding Boise City and the 1880 Census listed 44 residents at Middleton. The arrival of the railroad at Caldwell led to the establishment of a town there as of August 1883. Businessmen James A. McGee and Alexander Duffes filed the plat for nearby Nampa in 1886. Parma was settled around the same time, with the Old Fort Boise post office being moved to the town's location; it was incorporated in 1904. Ada County established precincts for each of the settlements with a combined 1890 Census population of 2,311. Significant settlement of Greenleaf and Notus started around 1904 with the two settlements listed as precincts at the 1910 census. Notus was incorporated in 1921 while Greenleaf was incorporated prior to 1980. Melba was incorporated in 1912 while Wilder was incorporated in 1919. The City of Star annexed a portion of territory in northeast Canyon County prior to 2007, becoming the county's ninth incorporated city. The majority of Star is located within Ada County. The Idaho Legislature created Canyon County from Ada County in an act approved March 7, 1891, effective at the November 26, 1892, election. Caldwell was established as the county seat. The county originally contained all of Canyon and Payette counties and part of Gem; Gem County formed in 1915 and Payette County in 1917.

History Hudson's Bay Company established Fort Boise in 1834 near what is now Parma, but abandoned it in 1855. Emigrants traveled through Canyon County on the Oregon Trail. Discovery of gold in the Boise Basin in 1862 brought settlement to the region again. The lower Boise River was fully contained within Boise County from 1863 until the formation of Ada County in 1864. Settlement of the lower Boise River west of Boise City was limited prior to the completion of the Oregon Short Line Railroad. Middleton was the first European settlement of Canyon County, starting in 1863. The 1870 Census for Ada County listed 76 residents of the Boise Valley, excluding Boise City and the 1880 Census listed 44 residents at Middleton. The arrival of the railroad at Caldwell led to the establishment of a town there as of August 1883. Businessmen James A. McGee and Alexander Duffes filed the plat for nearby Nampa in 1886. Parma was settled around the same time, with the Old Fort Boise post office being moved to the town's location; it was incorporated in 1904. Ada County established precincts for each of the settlements with a combined 1890 Census population of 2,311. Significant settlement of Greenleaf and Notus started around 1904 with the two settlements listed as precincts at the 1910 census. Notus was incorporated in 1921 while Greenleaf was incorporated prior to 1980. Melba was incorporated in 1912 while Wilder was incorporated in 1919. The City of Star annexed a portion of territory in northeast Canyon County prior to 2007, becoming the county's ninth incorporated city. The majority of Star is located within Ada County. The Idaho Legislature created Canyon County from Ada County in an act approved March 7, 1891, effective at the November 26, 1892, election. Caldwell was established as the county seat. The county originally contained all of Canyon and Payette counties and part of Gem; Gem County formed in 1915 and Payette County in 1917.

2000 census As of the 2000 census, there were 131,441 people, 45,018 households and 33,943 families living in the county. The population density was 223 people per square mile (86 people/km2). There were 47,965 housing units at an average density of 81 units per square mile (31 units/km2). The racial makeup of the county was 83.10% White, 0.32% Black or African American, 0.85% Native American, 0.80% Asian, 0.13% Pacific Islander, 12.17% from other races, and 2.62% from two or more races. Hispanic or Latino of any race were 18.61% of the population. 15.9% were of German, 12.7% English, 10.3% American and 7.6% Irish ancestry. There were 45,018 households, of which 39.80% had children under the age of 18 living with them, 60.70% were married couples living together, 10.10% had a female householder with no husband present, and 24.60% were non-families. 19.80% of all households were made up of individuals, and 8.40% had someone living alone who was 65 years of age or older. The average household size was 2.85 and the average family size was 3.28. 30.90% of the population were under the age of 18, 10.70% from 18 to 24, 28.30% from 25 to 44, 19.10% from 45 to 64, and 11.00% who were 65 years of age or older. The median age was 30 years. For every 100 females, there were 98.70 males. For every 100 females age 18 and over, there were 96.30 males. The median household income was $35,884 and the median family income was $40,377. Males had a median income of $29,418 compared with $22,044 for females. The per capita income for the county was $15,155. About 8.70% of families and 12.00% of the population were below the poverty line, including 14.50% of those under age 18 and 10.70% of those age 65 or over. Communities Cities Unincorporated communities Bowmont Huston Roswell Sunnyslope Walters Ferry, Idaho Politics Like the majority of Idaho, Canyon County is reliably Republican by comfortable margins. The last time a Democratic candidate carried the county was in 1936 by Franklin D. Roosevelt.

Meridian is a city located in Ada County, Idaho, United States. The population was 117,635 at the 2020 census, making it the second most populous city in the county and Idaho, after Boise, the state capital.

Rail transportation (1908–28) Following the raising of $4,000 to lay the Interurban rail line from Onweiler (Meridian and Ustick Roads), the tracks were completed into the village center. Turning east on Broadway and ending at East Second, the last car would spend the night in Meridian before returning to Boise early the next morning with passengers and freight. The interurban Station and Generator building (west one-third of the old library at Meridian and Idaho Streets) was built in 1912, and the line continued on to Nampa via Meridian. The tracks down Broadway were not used after 1912. The Interurban Company entered into receivership and closed in 1928 after 20 years of providing continuous transportation to neighboring towns. It was Meridian's main connection to the area outside the local community. The Union Pacific Railroad spur opened in 1900 and is currently operated by the Boise Valley Railroad. Many industrial customers continue to ship forest, agricultural, and chemical products along this corridor. Creamery (1929–70) The city's official website describes the history of the Ada County Dairymen's cooperative creamery as follows:The lowest days of the Great Depression brightened for area dairymen when the Ada County Dairymen's cooperative creamery began operation in 1929. It provided milk checks to those who were members of the cooperative, enabling them to pay their taxes and provide food for their families. Other community members hauled milk to the creamery and were employed by the creamery, whose product was Challenge Butter. The creamery ran seven days a week for 40 years. Additions and improvements were made while the plant was in full operation. Later years saw the Wyeth Laboratories affiliate with the creamery to manufacture SMA baby formula.

Creamery (1929–70) The city's official website describes the history of the Ada County Dairymen's cooperative creamery as follows:The lowest days of the Great Depression brightened for area dairymen when the Ada County Dairymen's cooperative creamery began operation in 1929. It provided milk checks to those who were members of the cooperative, enabling them to pay their taxes and provide food for their families. Other community members hauled milk to the creamery and were employed by the creamery, whose product was Challenge Butter. The creamery ran seven days a week for 40 years. Additions and improvements were made while the plant was in full operation. Later years saw the Wyeth Laboratories affiliate with the creamery to manufacture SMA baby formula.

Gem County is a county in the U.S. state of Idaho. As of the 2020 census, the population was 19,123. The county seat and largest city is Emmett. Gem County is part of the Boise metropolitan area. Gem County is home to the Idaho ground squirrel. History Named for the state nickname, "Gem State," the county was established on March 15, 1915, partitioned from Canyon County and Boise County. Fur trappers were in the area as early as 1818, and Alexander Ross explored Squaw Creek in 1824. Prospectors and miners moved through the county in 1862 en route to the gold rush in the Boise Basin around Idaho City, and by the next year irrigation began along the Payette River. Under Washington Territory, the area was part of Idaho County from the time of settlement until the territory south of the Payette River became part of Boise County at its creation in 1863. Picket's Corral, northeast of Emmett was the base of operations for a gang of horse thieves and "bogus dust peddlers" between 1862 and 1864. The Payette Vigilance Committee eliminated the gang, bringing safety for citizens of the area. The act creating Ada County in 1864 established the Ada County boundary common to Boise County as a line from Grimes Creek to Picket's Corral and then north from that point to the existing northern boundary of Boise County, leaving the areas outside of Emmett within Boise County. Jonathan Smith and Nathaniel Martin settled near Emmett about 1862. They established a ferry on the Payette River at Emmett in 1866. On May 31, 1867, a post office was established at the ferry and named Martinsville, which was renamed Emmettsville on October 31, 1868; postal officials shortened the name of the post office to Emmett in 1885. Census data for the area shows Squaw Creek Precinct under Boise County with a population of 30 in 1870. Ada County did not separately return precincts at that census. By 1890, Squaw Creek was split into two precincts. Those precincts were grouped with Horseshoe Bend at the 1890 census. The Emmett precinct contained 479 residents at that time. The Emmett area was transferred to Canyon County at its establishment in 1892.

History Named for the state nickname, "Gem State," the county was established on March 15, 1915, partitioned from Canyon County and Boise County. Fur trappers were in the area as early as 1818, and Alexander Ross explored Squaw Creek in 1824. Prospectors and miners moved through the county in 1862 en route to the gold rush in the Boise Basin around Idaho City, and by the next year irrigation began along the Payette River. Under Washington Territory, the area was part of Idaho County from the time of settlement until the territory south of the Payette River became part of Boise County at its creation in 1863. Picket's Corral, northeast of Emmett was the base of operations for a gang of horse thieves and "bogus dust peddlers" between 1862 and 1864. The Payette Vigilance Committee eliminated the gang, bringing safety for citizens of the area. The act creating Ada County in 1864 established the Ada County boundary common to Boise County as a line from Grimes Creek to Picket's Corral and then north from that point to the existing northern boundary of Boise County, leaving the areas outside of Emmett within Boise County. Jonathan Smith and Nathaniel Martin settled near Emmett about 1862. They established a ferry on the Payette River at Emmett in 1866. On May 31, 1867, a post office was established at the ferry and named Martinsville, which was renamed Emmettsville on October 31, 1868; postal officials shortened the name of the post office to Emmett in 1885. Census data for the area shows Squaw Creek Precinct under Boise County with a population of 30 in 1870. Ada County did not separately return precincts at that census. By 1890, Squaw Creek was split into two precincts. Those precincts were grouped with Horseshoe Bend at the 1890 census. The Emmett precinct contained 479 residents at that time. The Emmett area was transferred to Canyon County at its establishment in 1892.

Geography According to the U.S. Census Bureau, the county has a total area of 566 square miles (1,470 km2), of which 561 square miles (1,450 km2) is land and 4.8 square miles (12 km2) (0.8%) is water. It is the fifth-smallest county in Idaho by area. Adjacent counties Washington County - northwest Adams County - north Valley County - northeast Boise County - east Ada County - south Canyon County - southwest Payette County - west National protected area Boise National Forest (part) Demographics Racial and ethnic composition 2020 census As of the 2020 census, there were 19,123 people, 7,199 households, and 4,585 families living in the county. The median age was 44.1 years, with 23.7% of residents under the age of 18 and 23.0% 65 years of age or older. For every 100 females there were 100.6 males, and for every 100 females age 18 and over there were 96.9 males age 18 and over. The racial makeup of the county was 86.9% White, 0.2% Black or African American, 0.8% American Indian and Alaska Native, 0.5% Asian, 0.1% Native Hawaiian and Pacific Islander, 4.0% from some other race, and 7.5% from two or more races. Hispanic or Latino residents of any race comprised 9.0% of the population. 53.2% of residents lived in urban areas, while 46.8% lived in rural areas. There were 7,199 households in the county, of which 29.2% had children under the age of 18 living with them and 21.4% had a female householder with no spouse or partner present. About 23.3% of all households were made up of individuals and 13.0% had someone living alone who was 65 years of age or older. There were 7,563 housing units, of which 4.8% were vacant. Among occupied housing units, 77.9% were owner-occupied and 22.1% were renter-occupied.

8,666. The largest city and county seat is Mountain Home. Elmore County comprises the Mountain Home, ID Micropolitan Statistical Area, which is also included in the Boise-Mountain Home-Ontario, ID-OR Combined Statistical Area. History Elmore County was established February 7, 1889, with its county seat at Rocky Bar. It is named after the Ida Elmore mines, the area's greatest silver and gold producer of the 1860s, located near Silver City in Owyhee County. While the Oregon Trail crossed the Snake River in Elmore County, at Three Island Crossing near Glenns Ferry, the significant early settlements of Elmore County were mining settlements located primarily in northern Elmore County surrounding the ghost town of Rocky Bar. Settlement at Rocky Bar commenced in 1863 with the settlement having 560 residents at the Territorial Census of that year. Nearby, Atlanta was settled in 1864. Elmore County north of the Snake River was originally part of Alturas County when it was created in 1864 and Rocky Bar became its county seat. The portion of Elmore County south of the Snake River was within Owyhee County until 1930. A small portion of Ada County was also annexed in 1948, bringing Elmore to its present boundary. The settlement at Rocky Bar was impacted by poor management by mining companies, mining lawsuits, and its geographic remoteness between 1869 and 1880. The Wood River experienced a surge in settlement at Hailey starting in 1880 that led to Rocky Bar's loss of the county seat to Hailey in 1882. Rocky Bar would briefly become a county seat upon the creation of Elmore County in 1889. A station on the overland stage route, originally named Rattlesnake, was moved west to the railroad line and became Mountain Home. On February 4, 1891, the county seat was moved to Mountain Home. Construction of Mountain Home Air Force Base began in October 1942, twelve miles (19 km) southwest of Mountain Home. The base officially opened in August 1943 as a training base for bombers, and was an operational base under the Strategic Air Command (SAC) through 1965. It became a fighter base in 1966 under Tactical Air Command (TAC), which became Air Combat Command (ACC) in 1992. Anderson Ranch Dam is east of Mountain Home on the South Fork of the Boise River.

Unincorporated communities Atlanta Dixie Featherville King Hill Pine Tipanuk Ghost town Rocky Bar Politics Education School districts include: Residents in a portion of the county are in the area (but not the taxation zone) for College of Western Idaho.

History Elmore County was established February 7, 1889, with its county seat at Rocky Bar. It is named after the Ida Elmore mines, the area's greatest silver and gold producer of the 1860s, located near Silver City in Owyhee County. While the Oregon Trail crossed the Snake River in Elmore County, at Three Island Crossing near Glenns Ferry, the significant early settlements of Elmore County were mining settlements located primarily in northern Elmore County surrounding the ghost town of Rocky Bar. Settlement at Rocky Bar commenced in 1863 with the settlement having 560 residents at the Territorial Census of that year. Nearby, Atlanta was settled in 1864. Elmore County north of the Snake River was originally part of Alturas County when it was created in 1864 and Rocky Bar became its county seat. The portion of Elmore County south of the Snake River was within Owyhee County until 1930. A small portion of Ada County was also annexed in 1948, bringing Elmore to its present boundary. The settlement at Rocky Bar was impacted by poor management by mining companies, mining lawsuits, and its geographic remoteness between 1869 and 1880. The Wood River experienced a surge in settlement at Hailey starting in 1880 that led to Rocky Bar's loss of the county seat to Hailey in 1882. Rocky Bar would briefly become a county seat upon the creation of Elmore County in 1889. A station on the overland stage route, originally named Rattlesnake, was moved west to the railroad line and became Mountain Home. On February 4, 1891, the county seat was moved to Mountain Home. Construction of Mountain Home Air Force Base began in October 1942, twelve miles (19 km) southwest of Mountain Home. The base officially opened in August 1943 as a training base for bombers, and was an operational base under the Strategic Air Command (SAC) through 1965. It became a fighter base in 1966 under Tactical Air Command (TAC), which became Air Combat Command (ACC) in 1992. Anderson Ranch Dam is east of Mountain Home on the South Fork of the Boise River.