Volborthite

{{Infobox mineral

| name = Volborthite

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| image = Volborthite-65625.jpg

| imagesize = 260px

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| caption = Neon green crystals of volborthite are nestled in a vug in the matrix

| category = Polyvanadate minerals

| formula = Cu₃V₂O₇(OH)₂·2H₂O

| IMAsymbol = Vbo{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| molweight =

| strunz = 8.FD.05

| dana = 40.03.10.01

| system = Monoclinic

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = C2/m

| unit cell = a = 10.610(2) Å, b = 5.866(1) Å
c = 7.208(1) Å; β = 95.04(2)°; Z = 2

| color = Olive-green, yellow-green; green to yellow-green in transmitted light

| colour =

| habit = Aggregates of scaly crystals, rosettes

| twinning =

| cleavage = Perfect

| fracture =

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| mohs = {{frac|3|1|2}}

| luster = Vitreous, waxy, greasy, pearly

| streak = light green

| diaphaneity = Translucent

| gravity = 3.5 - 3.8

| density =

| polish =

| opticalprop = Biaxial (+/-)

| refractive = n_α = 1.793 n_β = 1.801 n_γ = 1.816

| birefringence = δ = 0.023

| pleochroism = Weak

| 2V = Measured: 63° to 83°

| dispersion = Translucent to Subtranslucent

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| fluorescence = Non-fluorescent

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| solubility = Soluble in acids

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| references = [http://rruff.geo.arizona.edu/doclib/hom/volborthite.pdf Handbook of Mineralogy][http://www.mindat.org/min-4200.html Mindat with location data][http://webmineral.com/data/Volborthite.shtml Webmineral]

}}

Volborthite is a mineral containing copper and vanadium, with the formula Cu₃V₂O₇(OH)₂·2H₂O. Found originally in 1838 in the Urals, it was first named knaufite but was later changed to volborthite for Alexander von Volborth (1800–1876), a Russian paleontologist.[http://www.galleries.com/Volborthite Mineral Galleries]

Tangeite (synonym: calciovolborthite), CaCuVO₄(OH), is closely related.