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Formula: Cu3V2O7(OH)2.2H2O
Hydrated normal vanadate, copper-bearing mineral.
Volborthite is one of the few minerals that contains the pyrovanadate anion
(V2O7)4- (JRS 12.26-27).
Crystal System: Monoclinic
Specific gravity: 3.5 to 3.8 measured, 3.52 calculated
Hardness: 3½
Streak: Light green
Colour: Olive-green, yellow-green; green to yellow-green in transmitted light
Solubility: Soluble in acids (Dana)
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.
Volborthite from Sofronovskii - Image
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 the Tintic Mining District, Utah, USA, volborthite, one of the few
vanadium species in the district, has so far (2024) been found only at the
Gold Chain and North Star mines. At both localities it occurs as very thin chartreuse-green plates in rosette-shaped
aggregates. At the Gold Chain mine, it is more frequently associated with
copper sulphides such as
brochantite and enargite, and
with oxidised copper minerals such as
azurite, malachite,
olivenite and tyrolite. At the
North Star mine, volborthite has been found mostly on the upper dumps, where it is associated with the
oxidation of copper sulphides (most commonly to
chrysocolla) and in some cases with minerals altered from
tellurates. The volborthite rosettes reach up to 2 mm in size, with
individual platy crystals around 1 mm wide
(MinRec 55.2.228).
Volborthite from Tintic - Image
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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