Penroseite

minerals

naumannite

clausthalite

tiemannite

Formula: (Ni,Co,Cu)Se2
Selenide, pyrite group
Specific gravity: 6.58 to 6.74
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

Hydrothermal 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).

At Kuusamo, North Ostrobothnia, Finland, penroseite is associated with clausthalite, sederholmite and trüstedtite (HOM).

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