Volborthite
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| Volborthite | |
|---|---|
 Volborthite crystals from the Ridenaur Mine, Prospect Canyon District, Coconino County, Arizona (size: 5.8 x 4.5 x 4.2 cm) |
|
| General | |
| Category | Polyvanadate minerals |
| Formula (repeating unit) |
Cu3V2O7(OH)2·2H2O |
| Strunz classification | 08.FD.05 |
| Crystal symmetry | Monoclinic prismatic H-M symbol (2/m) Space group: C 2/m |
| Unit cell | a = 10.610(2) Å, b = 5.866(1) Å, c = 7.208(1) Å; β = 95.04(2)° |
| Identification | |
| Color | Olive-green, yellow-green; green to yellow-green in transmitted light |
| Crystal habit | Aggregates of scaly crystals, rosettes |
| Crystal system | Monoclinic |
| Cleavage | Perfect |
| Mohs scale hardness | 3½ |
| Luster | Vitreous, waxy, greasy, pearly |
| Diaphaneity | Translucent |
| Specific gravity | 3.5 - 3.8 |
| Optical properties | Biaxial (+/-) |
| Refractive index | nα = 1.793 nβ = 1.801 nγ = 1.816 |
| Birefringence | δ = 0.023 |
| Pleochroism | Weak |
| 2V angle | Measured: 63° to 83° |
| Solubility | Soluble in acids |
| References | [1][2][3] |
Volborthite is a mineral containing copper and vanadium, with the formula Cu3V2O7(OH)2·2H2O. Found originally in 1838 in the Urals, it was named for Alexander von Volborth (1800-1876), a Russian paleontologist.
Tangeite (synonym: calciovolborthite), CaCuVO4(OH), is closely related.
Occurrence [edit]
Volborthite was first described in 1837 for an occurrence in the Sofronovskii Mine, Yugovskii Zavod, Perm, Permskaya Oblast, Middle Urals, Russia.[2]
It occurs as an uncommon oxidation mineral in vanadium bearing hydrothermal copper ores. It is associated with brochantite, malachite, atacamite, tangeite, chrysocolla, baryte and gypsum.[1]
References [edit]
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