Olivenite Locality: Tsumeb Mine (Tsumcorp Mine), Tsumeb, Otjikoto (Oshikoto) Region, Namibia (Locality at mindat.org) Size: thumbnail, 2.6 x 1.5 x 1.2 cm Oliven — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Olivenite
An olive-green copper arsenate forming brilliant prismatic crystals in oxidized copper deposits.
Intro adapted from Wikipedia (CC BY-SA).
Olivenite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Cu₂(AsO₄)(OH).
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Andalusite structural group.
Key properties: Mohs hardness 3; specific gravity 4.46; typically green or brown or yellow or gray; Olive-green to brown streak; Adamantine to vitreous, pearly to silky if fibrous luster; refractive index 1.805; optically biaxial.
IMA symbol Oli, grandfathered status — known before the IMA’s founding, named in 1789.
The most common secondary copper arsenate in the oxdized zone of hydrothermal copper deposits.
It is found associated with Conichalcite, clinoclase, tyrolite, cornetite, cornwallite, metazeunerite, scorodite, pharmacosiderite, spangolite, chalcophyllite, brochantite, malachite.
In allusion to its common olive-green color.
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