Bornite
Image: “Jonathan Zander (Digon3)" (CC BY-SA 3.0)
Mineral NameBornite
Chemical FormulaCu₅FeS₄
Mohs Hardness3
Crystal Systemorthorhombic
Lustermetallic
Streak Colorgrayish black
Cleavagepoor/indistinct on {111}
Fractureconchoidal
Specific Gravity5
Colorsreddish-brown, blue, green, purple, red
Transparencyopaque
Type LocalityButte, Montana, USA
Mineral GroupSulfides
Usesore of copper, collector
Associated Mineralschalcopyrite, pyrite, chalcocite, covellite
Raritycommon
Description
This sample of Bornite, also known as Peacock Ore, exhibits a vibrant iridescent tarnish with prominent blues, greens, purples, and reddish-browns on its metallic surface.
Geological Context
Bornite commonly forms in hydrothermal veins, porphyry copper deposits, and as a secondary mineral in the supergene enrichment zones of copper sulfide deposits.
