Roscoelite

minerals

carnotite

corvusite

hewettite

Formula: KV3+2(Si3Al)O10(OH)2
Phyllosilicate (sheet silicate), mica group
Specific gravity: 2.92 to 2.94
Hardness: 2½
Streak: Greenish white
Colour: Brown, dark green to black
Common impurities: Fe,Ca,Na,H2O
Environments

Sedimentary environments
Hydrothermal environments

Roscoelite is an early stage gangue mineral in low-temperature epithermal gold-silver-tellurium deposits, where it is associated with quartz, pyrite, carbonates, fluorite and gold. It also occurs in the oxidised portions of low-temperature sedimentary uranium-vanadium ores, associated with corvusite, hewettite, carnotite and tyuyamunite (HOM).

Localities

The type locality is the Stuckslager Mine, Coloma, Coloma Mining District, West Belt, El Dorado county, California, USA.

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