Underground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the same techniques used to excavate ores of gems, such as diamonds and rubies. Soft-rock mining refers to the excavation of softer minerals, such as salt, coal, and oil sands.
An adit or stulm is a horizontal or nearly horizontal passage to an underground mine. Miners can use adits for access, drainage, ventilation, and extracting minerals at the lowest convenient level. Adits are also used to explore for mineral veins. Although most strongly associated with mining, the term adit is sometimes also used in the context of underground excavation for non-mining purposes; for example, to refer to smaller underground passageways excavated for underground metro systems, to provide pedestrian access to stations, and for access required during construction.
Welkom is the second-largest city in the Free State province of South Africa, located about 140 kilometres (90 mi) northeast of Bloemfontein, the provincial capital. Welkom is also known as Circle City, City Within A Garden, Mvela and Matjhabeng. The city's Sesotho name, Matjhabeng means 'where nations meet', derived from the migrant labour system, where people of various countries such as Lesotho, Malawi and Mozambique etc. met to work in the mines of the gold fields.
Drift mining is either the mining of an ore deposit by underground methods, or the working of coal seams accessed by adits driven into the surface outcrop of the coal bed. A drift mine is an underground mine in which the entry or access is above water level and generally on the slope of a hill, driven horizontally into the ore seam.
Harmony Gold is the largest gold mining company in South Africa. Harmony operates in South Africa and in Papua New Guinea. The company has nine underground mines, one open-pit mine and several surface operations in South Africa. In Papua New Guinea, it has Hidden Valley, an open-pit gold and silver mine and a 50% interest in the Morobe Mining Joint Venture, which includes the Wafi-Golpu project and extensive exploration tenements. Outside the joint venture, Harmony's own exploration portfolio focuses principally on highly prospective areas in Papua New Guinea.
The Widgiemooltha Komatiite is a formation of komatiite in the Yilgarn Craton of Western Australia.
During the late 1970s and through the 1980s, Mohave and Coconino County, Arizona, immediately north and south of the Grand Canyon and west of the Navajo Indian Reservation were explored for Arizona breccia pipe uranium mineralization. The search area included the region between the Colorado River and the Utah border known as the “Arizona Strip”.
Uranium ore deposits are economically recoverable concentrations of uranium within the Earth's crust. Uranium is one of the most common elements in the Earth's crust, being 40 times more common than silver and 500 times more common than gold. It can be found almost everywhere in rock, soil, rivers, and oceans. The challenge for commercial uranium extraction is to find those areas where the concentrations are adequate to form an economically viable deposit. The primary use for uranium obtained from mining is in fuel for nuclear reactors.
Although the subsoil of Ivory Coast contained many other minerals, none existed in commercially exploitable amounts, given the high costs of extraction. The mining sector contributes to 13% of exports.
The following outline is provided as an overview of and topical guide to mining:
SAG/SDAG Wismut was a uranium mining company in East Germany during the time of the Cold War. It produced a total of 230,400 tonnes of uranium between 1947 and 1990 and made East Germany the fourth largest producer of uranium ore in the world at the time. It was the largest single producer of uranium ore in the entire sphere of control of the USSR. In 1991 after German reunification it was transformed into the Wismut GmbH company, owned by the Federal Republic of Germany, which is now responsible for the restoration and environmental cleanup of the former mining and milling areas. The head office of SDAG Wismut / Wismut GmbH is in Chemnitz-Siegmar.
Stoping is the process of extracting the desired ore or other mineral from an underground mine, leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to collapse into the stope, although in most cases artificial support is also provided.
The Pyne Mine was a vertical shaft iron ore mine operated by the Woodward Iron Company and located near the Lacey's Chapel community outside Bessemer, Alabama, in Shades Valley. It was, along with Woodward's Songo Mine, one of only two shaft mines dug in the Birmingham District, and the last ore mine to operate in the region, closing in 1971.
The San Manuel Copper Mine was a surface and underground porphyry copper mine located in San Manuel, Pinal County, Arizona. Frank Schultz was the original discoverer, in 1879, but the main body of the deposits were discovered by Henry W. Nichols in 1942. The exploration drilling went on from 1943 to 1948, with the first mine shaft built 1948. Louis Lesser developed a mining city to service Nichols’ newly discovered deposits, and the development was completed about 1954. The first major production began in 1955. The mine and smelter were permanently closed in 2003.
Orex Exploration is a former Canadian gold mining company that conducted exploration work on mining properties it owned in the Goldboro and Guysborough County areas of Nova Scotia. The properties owned by Orex were the sites of the former Boston Richardson Mine, Dolliver Mountain Mine, West Goldbrook Mine, and East Goldbrook Mine which operated between 1892 and 1912. Headquartered in Rouyn-Noranda, Quebec, the company was founded in 1987 and raised funds for exploration work, in part, by issuing stocks traded on the Montreal Stock Exchange and then the TSX Venture Exchange. It became a subsidiary of Anaconda Mining Inc. after Anaconda acquired the company in a stock swap deal in 2017.
The le Puy Mine is an ancient lead mine in the northwestern Massif Central, France. The mine produced mainly silver-bearing galena.
Manganvesuvianite is a rare mineral with formula Ca19Mn3+(Al,Mn3+,Fe3+)10(Mg,Mn2+)2(Si2O7)4(SiO4)10O(OH)9. The mineral is red to nearly black in color. Discovered in South Africa and described in 2002, it was so named for the prevalence of manganese in its composition and its relation to vesuvianite.
Hajigak Mine is the best known and largest iron oxide deposit in Afghanistan, located near the Hajigak Pass, with its area divided between Maidan Wardak and Bamyan provinces. It has the biggest untapped iron ore deposits of Asia.
The Gloria mine is a mine located in the north of South Africa. Gloria represents one of the largest manganese reserve in South Africa having estimated reserves of 156.2 million tonnes of manganese ore grading 33% manganese metal.
Effenbergerite is the natural occurrence of the color Han blue.It was first found in the Wessels mine, Kalahari Manganese Field, South Africa. Effenbergerite was approved as a valid mineral species by the IMA in 1993.
