Covellite — Photo: Raimond Spekking · CC BY-SA 4.0
Covellite
Also known as: Covelline.
A rare indigo-blue copper sulfide prized by collectors for its metallic iridescence, though only a minor ore.
Intro adapted from Wikipedia (CC BY-SA).
Covellite is an IMA-recognized mineral species in the sulfide class, with the chemical formula CuS.
It crystallizes in the hexagonal crystal system (space group P6_3/mmc). It is a member of the Covellite structural group.
Key properties: Mohs hardness 1.5–2; specific gravity 4.6–4.76; typically blue or purple; Lead-gray, shining streak; Submetallic, inclining to resinous, somewhat pearly on cleavage; subresinous to dull when massive luster; optically uniaxial.
IMA symbol Cv, grandfathered status — known before the IMA’s founding, named in 1832.
Most commonly of secondary origin in the zone of oxidation in sulfide copper deposits. Rarely of primary hydrothermal origin. Widespread in most copper deposits; common as an iridescent tarnish on other sulfides.
It is found associated with Chalcopyrite, chalcocite, djurleite, bornite, enargite, pyrite, other sulfides.
The mineral was named to honor Niccolò Covelli (1790–1829), discoverer of Vesuvian covellite.
Collections: Metals & Native Elements, Collector Favorites.