Mining
is an open-pit copper mine]]\n
Mining is the extraction of
valuable minerals or other geological materials from the earth, usually (but not always) from an
ore body or vein. Materials commonly recovered by mining include
bauxite,
coal,
copper,
diamonds,
iron (from
haematite and
limonite),
gold,
lead,
manganese,
magnesium,
nickel,
phosphate,
platinum,
salt,
silver,
tin,
titanium,
uranium, and
zinc. Other highly useful materials that are mined include
clay,
sand, cinder,
gravel, granite, and
limestone.
History
\nThe first mining operation on Earth may have been the turquoise mine operated by the ancient Egyptians at Wady Maghareh on the Sinai Peninsula. Turquoise was also mined in pre-Columbian America in the Cerillos Mining District in New Mexico, where a mass of rock 200 feet in depth and 300 feet in width was removed with stone tools; the mine dump covers 20 acres.
Mining techniques
\nMining techniques can be divided into two basic excavation types: 1) open-cast or open-pit mining and 2) tunneling by shafts into the earth.\n*Open excavations\n**Open-pit mining\n**Quarrying\n**Strip mining\n**Placer mining
- Tunnel mines\n**Tunnel mining\n**Deep mining\n**Drift mining\n**Hard rock mining\n \nBioleaching is the application of bacteria to extract metals from an ore.
Environmental effects
\nMining can have devastating impacts on the environment due to the massive rearrangement of minerals within the earth. The result can be unnatural high concentrations of some chemical elements over a significantly wider area of surface. Combined with the effects of water and the new 'channels' created for water to travel through, collect in, and contact with these chemicals, a situation is created where mass-scale contamination can occur.
Some examples of environmental problems associated with mining operations are:
- Tar Creek, an abandoned mine in Northeastern Oklahoma that is now an Environmental Protection Agency superfund site. Water in the mine has leaked through into local groundwater, contaminating it with metals such as lead and cadmium. [1]
- Scouriotissa, a copper mine in Cyprus that has been abandoned. Contaminated dust blows off this site.
- Berkeley Lake, an abandoned pit mine in Butte, Montana that has filled with water which is now acidic and poisonous.
See also
\n* Coal mining\n*
Acid mine drainage
References
\n* Tom Morrison. 1992. Hardrock Gold: A Miner's Tale (ISBN 0806124423)\n* Geobacter Project: Gold mines may owe their origins to bacteria (in
PDF format)
Category:Geology\nCategory:Gold Rush\nCategory:Mining
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