Bornite
Image: <a href="//commons.wikimedia.org/wiki/User:Islam90" title="User:Islam90">Islam90</a> (CC BY-SA 4.0)
Mineral NameBornite
Chemical FormulaCu₅FeS₄
Mohs Hardness3
Crystal Systemorthorhombic
Lustermetallic
Streak Colorgrayish black
Cleavagepoor/indistinct on {111}
Fractureconchoidal to uneven
Specific Gravity5
Colorscopper-red, brownish-bronze, purple, blue, red, iridescent
Transparencyopaque
Type LocalityButte, Montana, USA
Mineral GroupSulfides
Usescopper ore
Associated Mineralschalcopyrite, pyrite, chalcocite, covellite
Raritycommon
Description
Bornite is a copper-iron sulfide mineral, typically displaying a copper-red to brownish-bronze color on fresh surfaces, which rapidly tarnishes to iridescent shades of blue, purple, and red, earning it the nickname 'peacock ore'. The image shows a microscopic view of the mineral in normal and polarized light.
Geological Context
Bornite is a common primary copper ore mineral found in hydrothermal veins, contact metamorphic deposits, and disseminated in igneous rocks. It often forms in association with other copper sulfides in porphyry copper deposits.
