Copper mining in the United States the northwest part of the state in the early 1850s, and mining began in 1855. The ore is massive sulfide and disseminated ore in mica schist and gneiss, and amphibole schist and gneiss. The principal ore mineral is chalcopyrite, which occurs with pyrrhotite and pyrite, The mine operated until 1883, then worked sporadically until large-scale mining began in 1957. The mine closed for good in 1962. Total production was 31,000 tonnes of copper, 9,400 ounces of gold, and 145,000 ounces of silver. Copper was mined at Creta from 1965 to about 1975. The ore 2% to 4.5% copper as chalcocite
Chalcopyrite chalcopyrite has no solid solution series with any other sulfide minerals. There is limited substitution of Zn with Cu despite chalcopyrite having the same crystal structure as sphalerite. Minor amounts of elements such as Ag, Au, Cd, Co, Ni, Pb, Sn, and Zn can be measured (at part per million levels), likely substituting for Cu and Fe. Selenium, Bi, Te, and As may substitute for sulfur in minor amounts. Chalcopyrite is present with many ore-bearing environments via a variety of ore forming processes. Chalcopyrite is present in volcanogenic massive sulfide ore deposits and sedimentary exhalative deposits, formed by deposition of