Copper mining in the United States
Top copper producing states in 2014 were (in descending order) Arizona, Utah, New Mexico, Nevada, and Montana.
In 2013, American copper mining produced 28,500 metric tons of molybdenum, worth about $700–800 million, which was 47% of total US production.
[4] Other byproducts of the copper extraction process included silver, and minor amounts of rhenium and platinum-group metals.
Russian explorers discovered copper on the Kasaan Peninsula of Prince of Wales Island in southeastern Alaska about 1865.
Copper is present as chalcopyrite, occurring with magnetite, pyrite, garnet, epidote, diopside, and hornblende, in replacement deposits in greenstone.
[18] At Mule Canyon, south of Tombstone, Arizona, in 1877, a soldier chasing Apache Indians found copper at Bisbee.
Twelve active copper mines in Arizona directly employ nearly 10,000 workers, not including contractors and sub-contractors.
[21] The Napoleon mine at Copperopolis in Calaveras County opened in 1860, and was so productive that it ignited a boom in other copper-mining properties from 1862 to 1866.
The orebody is a massive sulfide deposit of pyrite, chalcopyrite, and pyrrhotite along a shear zone in the Franciscan Formation.
[24] At the northern end of the Sierra Nevada, in Plumas County, the Walker, Engels, and Superior mines together produced more than 140 thousand tons of copper.
The most productive was in Frederick County, in a belt of chalcopyrite ore in schist and limestone stretching from New London to Libertytown.
Another district contains chalcopyrite, chalcocite, and bornite, in a fault zone that runs 25 miles in slate from Sykesville to Finksburg in Carroll County.
[31] Native Americans mined copper from small pits on the Keweenaw Peninsula of northern Michigan as early as 3000 BC.
Present plans call for the mine to produce 72 million lb (33 thousand t) of copper annually, along with nickel, cobalt, platinum, palladium, and gold.
[39] The only remaining active copper mine at Butte is the Continental pit, operated by Montana Resources LLP.
A Native American showed mineralization to prospectors in 1867, and the district started in a small way as a lode gold producer.
[44] The copper occurs as chalcocite, bornite, covellite, cuprite, and malachite, in quartzite of the Silurian High Falls Formation.
Native Americans had mined turquoise associated with the copper deposits at present-day Tyrone in Grant County, New Mexico.
[46] Some copper has been produced from three deposits in sandstone of the Triassic Chinle Formation in the Nacimiento Mountains near Cuba, New Mexico.
[49] Copper was discovered at the Ore Knob deposit in the northwest part of the state in the early 1850s, and mining began in 1855.
By 1732, the Gap mine in Lancaster County was operating, owned by shareholders including Gouverneur Morris and Thomas Penn.
[55] The Copper Basin, located in the extreme southeastern corner of Tennessee in Polk County, was the center of a major copper-mining district from 1847 until 1987.
Small amounts of copper were mined from Permian redbeds in Archer and Foard counties of north-central Texas in the 1860s and 1870s.
The Bingham Canyon Mine southwest of Salt Lake City has been one of the world's largest copper producers for more than 100 years.
The primary copper mineral is chalcocite, which is thought to have been deposited from solutions ascending through the Lisbon Valley Fault.
At the time the assets were acquired by CS, the measured, indicated and inferred resources were approximately 600 million pounds of copper; plus gold, silver, and magnetite.
The Chewelah district in Stevens County produced 1.7 million troy ounces (53 tonnes) of silver and 5,000 metric tons of copper from quartz-carbonate veins.
[75] The copper deposit of the Flambeau mine was discovered in 1969 1.5 miles south of Ladysmith in Rusk County, and produced from an open pit from 1993 to 1997.
[76] The Wisconsin Department of Natural Resources continues long-term vegetation and groundwater monitoring of the site to assure that the reclamation was done successfully.
[79] Although no copper mines have operated in Wyoming in recent years, there are several properties with large-tonnage copper-silver porphyries (Tertiary) in the Absaroka Mountains east of Yellowstone, stratabound copper-silver-zinc massive sulfides (Triassic-Jurassic) in the Lake Alice district in the overthrust belt of Western Wyoming, several volcanogenic massive sulfide (copper, lead, zinc, silver) deposits in the Encampment district, a potentially major stratabound copper-gold paleoplacer (Proterozoic) at the Ferris-Haggarty property in the Sierra Madre, a Proterozoic copper-gold porphyry at the Copper King property in the Laramie Range, and other properties of interest (Hausel, 1997)[citation needed].
