Bornite is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the cubic system. It has a brown to copper-red color on fresh surfaces that tarnishes to an iridescent purple surface. Its purple to bronze iridescence gives it the nickname peacock ore. Bornite is an important copper ore mineral and occurs widely in porphyry copper deposits along with the more common chalcopyrite. Chalcopyrite and bornite are both typically replaced by chalcocite and covellite in the supergene enrichment zone of copper deposits. Bornite is also found in pegmatites. It is important for its copper content of about 63 percent by mass and is found in Arizona, Butte, Montana, and Mexico.
Bornite is isometric, has a hardness of 3, a specific gravity of 5.7, a streak of gray-black, poor cleavage, and is used in industrial copper ores.
Bornite has a molar mass of 342.681 g/mol.