Chalcopyrite

The most important copper ore mineral, chalcopyrite is a copper iron sulfide (CuFeS2) present in nearly all sulfide deposits. It crystallizes in the tetragonal system as tetrahedral or massive aggregates and carries a metallic luster, a greenish-black streak, and poor cleavage. Its brass-yellow surface often develops an iridescent tarnish. Chalcopyrite is frequently mistaken for pyrite but is set apart by a deeper yellow color, a lower Mohs hardness of 3.5 to 4, and its distinctive streak. Specific gravity ranges from 4.10 to 4.30, and the mineral remains the leading global source of copper. Its poor cleavage and conchoidal to uneven fracture further separate it from the cubic-cleaving sulfides such as galena.

Chalcopyrite is the most important copper ore mineral and occurs in virtually all sulfide deposits. It is often confused with pyrite but can be distinguished by its deeper yellow color, lower hardness, and greenish-black streak.