Bornite Hungarian family) (1742–1791). Bornite Bornite, also known as peacock ore, is a sulfide mineral with chemical composition CuFeS that crystallizes in the orthorhombic system (pseudo-cubic). Bornite has a brown to copper-red color on fresh surfaces that tarnishes to various iridescent shades of blue to purple in places. Its striking iridescence gives it the nickname "peacock copper" or "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
Southeast Missouri Lead District sphalerite, and chalcopyrite. Gangue minerals associated with the economic minerals include pyrite, calcite, dolomite, and quartz. Specimens from the Lead Belt are highly prized by gem and mineral collectors and are found in museums worldwide. The ore minerals of the Lead Belt are primarily hosted by bacterial stromatolite reefs and associated oolitic rocks of the dolomitic Bonneterre Formation. This Cambrian age formation was deposited in a shallow sea around the Precambrian age St. Francois Mountains, which formed an island archipelago. Ore mineralization most likely occurred during the late Pennsylvanian and/or Permian periods when warm metal and petroleum bearing fluids from