Chalcopyrite is a copper
iron sulfide mineral that crystallizes in the tetragonal system. It has
the chemical composition CuFeS2. 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 (Cu5FeS4), chalcocite (Cu2S), covellite
(CuS), digenite (Cu9S5); carbonates such as malachite and azurite, and
rarely oxides such as cuprite (Cu2O). Chalcopyrite is rarely found in association
with native copper.