Images
Formula: (Ni,Co,Cu)Se2
Selenide, pyrite group,
cobalt-bearing mineral
Crystal System: Isometric
Specific gravity: 6.58 to 6.74 measured, 6.7 calculated
Hardness: 2½ to 3
Streak: Black
Colour: Steel-grey
Solubility: Effervesces with nitric acid (AM 11.39}
Common impurities: Ag,Hg,Pb,Fe,S
Environments
Localities
At the type locality, the Virgen de Surumi mine, Pakajake Canyon, Chayanta Province, Potosí, Bolivia, penroseite occurs in hydrothermal
veins associated with naumannite, clausthalite,
gersdorffite, tiemannite,
pyrite and chalcopyrite. Some of the penroseite
appears to be microscopically intergrown with naumannite and
clausthalite
(HOM, Mindat, R&M 93.4.366-367).
Penroseite from the Virgen de Surumi Mine -
Image
At Kuusamo, North Ostrobothnia, Finland, penroseite is associated with clausthalite,
sederholmite and trüstedtite
(HOM).
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