Bornite

Bornite is a copper iron sulfide mineral with the formula Cu₅FeS₄. Its bronze color often develops an iridescent purple, blue, or red tarnish on exposure to air.

Sulfide mineral: A mineral in which sulfur is combined with one or more metals or metalloids. Bornite belongs to this mineral class because sulfur bonds with copper and iron.
Copper ore: Rock or mineral material containing enough copper to be mined and processed economically. Bornite is mined as a copper-bearing mineral, often alongside other sulfides.
Bingham Canyon Mine: A large porphyry copper mine in the Oquirrh Mountains of Utah. Bornite occurs among the copper sulfides found in this major porphyry deposit.
Chalcocite: A copper sulfide mineral with the formula Cu₂S and a dark gray to black metallic appearance. Unlike bornite, chalcocite contains no iron and has a distinctly different composition.
Crystal system: A classification of crystals based on their symmetry and lattice geometry. Bornite’s symmetry and structure vary with temperature, shaping its crystallographic classification.
Copper extraction: The industrial processes used to recover copper from ores and concentrates. Bornite concentrates can be treated to recover their copper content.
Butte, Montana: A mining city in Montana built around a major copper and silver district. Bornite is among the copper minerals reported from the Butte mining district.
Covellite: A copper sulfide mineral with the formula CuS, often showing an indigo-blue color. Covellite’s blue body color contrasts with bornite’s bronze base and tarnish colors.
Mineral hardness: A measure of a mineral’s resistance to scratching, commonly expressed using the Mohs scale. Bornite’s low Mohs hardness helps distinguish it from harder metallic-looking sulfides.
Copper: A reddish, highly conductive metallic chemical element with symbol Cu. Copper is the principal economically valuable metal supplied by bornite.

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