Chalcopyrite Chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical formula CuFeS. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black. On exposure to air, chalcopyrite oxidises to a variety of oxides, hydroxides and sulfates. Associated copper minerals include the sulfides bornite (CuFeS), chalcocite (CuS), covellite (CuS), digenite (CuS); carbonates such as malachite and azurite, and rarely oxides such as cuprite (CuO). Chalcopyrite is rarely found in association with native copper. Natural
Argentine Pass iron pyrite, cupriferous pyrite (chalcopyrite), and some tetrahedrite. This was the first major discovery of silver ore in Colorado. They named the deposit the Belmont Lode (from the French for "beautiful mountain"), and the surrounding area came to be known as the Argentine mining district (from "argentum", Latin for silver). The discovery led to the growth of Georgetown as an early center of the silver mining industry in Colorado, although development was slowed by a general ignorance of how to properly treat the ore, by the high cost of transportation from the mines, and by the climate at that altitude.