Hewettite

hewettite

rauvite

patronite

carnotite

Images

Formula:CaV5+6O16.9H2O
Vanadium oxysalt, hewettite group
Specific gravity: 2.51 to 2.61
Hardness: Extremely soft
Streak: Brownish red
Colour: Deep red; chocolate brown (upon exposure); red to orange in transmitted light
Solubility: Slightly soluble in water
Environments

Sedimentary environments

Hewettite is a secondary mineral resulting from the alteration of patronite, or from the alteration of less-oxidised vanadium minerals in Colorado Plateau-type uranium-vanadium deposits, where it is associated with carnotite, corvusite, fervanite, metahewettite, montroseite, navajoite, rauvite, steigerite and tyuyamunite. It may reversibly dehydrate to metahewettite. (Mindat, HOM).

Localities

The type locality, the Ragra Mine, Huayllay District, Pasco Province, Pasco, is a very rich vanadium deposit in sedimentary rocks. Here hewettite is an alteration product of patronite and occurs associated with it (Mindat, HOM).

At the Gallagher Vanadium Property, Cochise County, Arizona, USA, hewettite has been seen on the dump as individual 1–2-mm crystals and as fibrous mats associated with weathered vanadinite and calcite (R&M 90-4.343).

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