Covellite
Image: Didier Descouens (CC BY 3.0)
Mineral NameCovellite
Chemical FormulaCuS
Mohs Hardness1.5
Crystal Systemhexagonal
Streak Colorlead gray to black
Cleavageperfect on {0001}
Fractureuneven
Specific Gravity4.6
Colorsindigo blue, purple, iridescent blue, iridescent purple
Transparencyopaque
Type LocalityLeonard Mine, Butte, Butte District, Silver Bow County, Montana, USA
Mineral GroupSulfides
Usescopper ore, collector
Associated Mineralschalcocite, bornite, chalcopyrite, pyrite
Rarityuncommon
Description
This specimen of covellite displays a striking iridescent play of colors, predominantly deep purple and electric blue, over a dark, platy surface. The mineral exhibits a distinct layered or foliated texture with a submetallic sheen.
Geological Context
Covellite typically forms in hydrothermal veins and is often found as a secondary mineral in the supergene enrichment zones of copper deposits, resulting from the alteration of other copper sulfides. It can also occur as a primary mineral in some high-temperature deposits.
