Which mineral is the principal ore of copper and has the formula CuFeS₂?

Chalcopyrite is the principal ore mineral of copper and has the chemical formula CuFeS₂.

Its name comes from Greek words meaning “copper” and “pyrite,” reflecting its brass-yellow color and metallic appearance. Chalcopyrite forms in many hydrothermal ore deposits, where hot, mineral-rich fluids move through fractures in Earth’s crust. It commonly occurs with pyrite, sphalerite, and galena.

Although chalcopyrite contains copper, iron, and sulfur, it is not the same mineral as pyrite, whose formula is FeS₂. Chalcopyrite is softer than pyrite and often tarnishes to vivid purple, blue, or green colors. This colorful surface coating is called peacock ore in some markets, although the name may also be used for treated or related specimens.

Copper is extracted by crushing and concentrating chalcopyrite ore, followed by smelting and refining. Copper from these deposits is used in electrical wiring, motors, plumbing, and electronics. Malachite is also a copper mineral, but it is mainly valued as an indicator mineral and ornamental material rather than the world’s principal copper ore.