Volborthite

vanadate

tangeite

Formula: Cu3V2O7(OH)2.2H2O
Hydrated normal vanadate, copper mineral. Volborthite is one of the few minerals that contains the pyrovanadate anion (V2O7)4- (JRS 12.26-27).
Specific gravity: 3.5 to 3.8
Hardness: 3½
Streak: Light green
Colour: Olive-green, yellow-green; green to yellow-green in transmitted light
Solubility: Soluble in acids (Dana)
Environments

Hydrothermal environments

Volborthite is an uncommon secondary supergene copper-vanadium mineral found in the oxidised zones of vanadium-bearing hydrothermal deposits (Mindat, HOM ), associated with brochantite, malachite, atacamite, tangeite, chrysocolla, baryte and gypsum (HOM), also vésigniéite (JRS 12.26-27).

The type locality is the Sofronovskii copper mine, Yugovskii Zavod, Perm', Permskaya Oblast, Russia

At Wheal Edward, St Just, Cornwall, England, UK, volborthite is a rare member of the supergene assemblage in copper and tin bearing lodes associated with the Land's End Granite. It is associated with metazeunerite (JRS 11.54-58).

At the Butterley and Blaby Brick Pit, Glen Parva, Leicestershire, England, UK, volborthite has been found as encrustations on the surface of vanadium-rich nodules in the Mercia Mudstone. It has also been found on the etched surfaces of gypsum and on joints in the rock in the immediate vicinity of nodules (JRS 11.54-58).

At New Cliffe Hill Quarry, Stanton under Bardon, Leicestershire, England, UK, crusts of volborthite coat fractures in diorite (JRS 11.54-58)

At Newhurst quarry, Shepshed, Leicestershire, England, UK, volborthite has been found as encrustations in void spaces between calcite crystals, in a breccia associated with a fault or shear zone which contained wallrock clasts cemented by calcite crystals and hematite. The volborthite is associated with zálesíite and malachite (RES p200, JRS 11.54-58).

At Monument #1 mine, Monument Valley, Navajo county, Arizona, USA, volborthite occurs in siltstone with carnotite, hewettite, metatyuyamunite, rauvite and tyuyamunite (Dana, AM 59.372-373).

At the Manganese mine, Keweenaw county, Michigan, USA, Volborthite occurs as microcrystalline coatings on massive calcite associated with malachite, chrysocolla and cuprite (R&M 89.6.513).

At Richardson in the canyon of the Colorado River, Grand county, Utah, volborthite is found as a secondary mineral in sandstone (Dana).

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