chalcopyrite

Chalcopyrite (CuFeS2) is a copper iron sulfide mineral and the most important primary ore of copper. It occurs in a wide range of sulfide deposits, including porphyry copper systems, hydrothermal veins, and contact metamorphic zones, and is frequently associated with pyrite, bornite, sphalerite, and quartz.

Crystallography and appearance: It belongs to the tetragonal system and commonly forms massive aggregates or well-shaped crystals. Its color ranges from brassy yellow to golden yellow with an iridescent tarnish. It has a metallic luster, a greenish-black streak, and a hardness of 3.5–4 on the Mohs scale. Its specific gravity is about 4.1–4.3, and its cleavage is indistinct with an uneven to conchoidal fracture.

Weathering and alteration: At or near the surface, chalcopyrite can weather to copper oxides and secondary minerals such as malachite and azurite. Weathering processes can also lead to the deposition of secondary copper-bearing coatings in ore dumps and tailings.

Economic importance and processing: Chalcopyrite is the principal copper ore worldwide. Ore processing typically involves crushing and grinding, concentration by froth flotation to produce a copper-rich concentrate, followed by roasting and smelting to obtain blister copper and, ultimately, refined copper.

Name and etymology: The name chalcopyrite derives from the Greek chalkos, meaning copper, and pyrite, meaning stone that strikes fire, reflecting its copper content and its superficial resemblance to pyrite. It remains a major mineral in economic geology and mineral collections.