Bornite
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Mineral NameBornite
Chemical FormulaCu₅FeS₄
Mohs Hardness3
Crystal Systemorthorhombic
Lustermetallic
Streak Colorgrayish black
Cleavagepoor/indistinct on {111}
Fractureconchoidal to uneven
Specific Gravity5
Colorscopper-red, reddish-brown, iridescent blue, purple, red
Transparencyopaque
Type LocalityCornwall, England
Mineral GroupSulfides
Usescopper ore
Associated Mineralschalcopyrite, pyrite, covellite, chalcocite, enargite
Raritycommon
Description
Bornite is a copper iron sulfide mineral characterized by its rapid tarnishing to iridescent shades of blue, purple, and red, giving it the nickname 'peacock ore'. Fresh surfaces are typically a reddish-brown or copper-red.
Geological Context
It is a common primary copper ore mineral found in hydrothermal veins, contact metamorphic deposits, and disseminated in mafic igneous rocks. It forms in a variety of sulfide deposits, often associated with other copper sulfides.
