Sherwoodite

sherwoodite

selenium

metatyuyamunite

melanovanadite

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Formula: Ca4.5AlV4+2V5+12O40.28H2O
Vanadate
Specific gravity: 2.8
Hardness: 2
Streak: Pale blue
Colour: Dark bluish black (fresh), blue-green, yellow-green (altered)
Solubility:
Common impurities:
Environments

Sedimentary environments
Hydrothermal environments

Sherwoodite is an oxidation product of lower valent vanadium minerals, on fracture surfaces and replacing fossil wood in Colorado Plateau-type sandstone uranium-vanadium deposits (Webmin). Associated minerals include selenium, metatyuyamunite and melanovanadite (HOM).

Localities

At the Ragra mine (Minasragra), Huayllay District, Pasco Province, Pasco, Peru, sherwoodite is associated with pascoite, pyrite, copper, gypsum, patronite and melanovanadite (HOM).

The type locality is the Peanut mine, Bull Canyon, Uravan Mining District, Montrose County, Colorado, USA. Sherwoodite is widely distributed in the Uravan mineral belt; localities include the Matchless mine, Mesa county, Colorado, the Shadyside mine, San Juan county, New Mexico, the Peanut mine, Montrose county, Colorado, and several other mines. Another locality, the Fall Creek mine, San Miguel County, Colorado, is in the Entrada sandstone.
Sherwoodite is an oxidation product of lower valent vanadium minerals. It occurs as coatings on fracture surfaces and along partings in vanadium-bearing sandstone, and along fracture surfaces in mineralised coalified wood. It is commonly associated with native selenium, metatyuyamunite, melanovanadite and an undescribed vanadium mineral resembling hewettite. It alters to an ill-defined, fine-grained green material, probably a poorly crystallised compound of quinquivalent vanadium (AM 43.749-755).

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