Cuprite

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, France; several places in Cornwall, England; Broken Hill, Australia; and Tsumeb, Namibia. It is abundant in the copper districts of the southwestern U.S., as at Bisbee, Arizona. For detailed physical properties, see oxide mineral.

Cuprite has two unusual varieties. Chalcotrichite, or plush copper ore, is loosely matted aggregates of capillary crystals with a rich carmine colour and a silky lustre. Tile ore is a soft, earthy variety that is brick-red to brownish red; it often contains admixed hematite or limonite and has been formed by the alteration of chalcopyrite.