cuprite
soft, heavy, red oxide mineral (Cu2O) that is an important ore of copper. A secondary mineral often formed by the weathering of copper sulfide minerals, cuprite is widespread as brilliant crystals, grains, or earthy masses in the oxidized zone of copper lodes. Deposits have been found at Chessy, Fr.; several places in Cornwall, Eng.; Broken Hill, Australia; and Tsumeb, South West Africa/Namibia. It is abundant in the copper districts of the southwestern U.S., as at Bisbee, Ariz. For detailed physical properties, see oxide mineral (table)
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