| Volborthite | |
| Category: | Polyvanadate minerals |
| Formula: | Cu3V2O7(OH)2·2H2O |
| Imasymbol: | Vbo[1] |
| 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 |
| Habit: | Aggregates of scaly crystals, rosettes |
| Cleavage: | Perfect |
| Luster: | Vitreous, waxy, greasy, pearly |
| Streak: | light green |
| Diaphaneity: | Translucent |
| Gravity: | 3.5 - 3.8 |
| Opticalprop: | Biaxial (+/-) |
| Refractive: | nα = 1.793 nβ = 1.801 nγ = 1.816 |
| Birefringence: | δ = 0.023 |
| Pleochroism: | Weak |
| 2V: | Measured: 63° to 83° |
| Dispersion: | Translucent to Subtranslucent |
| Fluorescence: | Non-fluorescent |
| Solubility: | Soluble in acids |
| References: | [2] [3] [4] |
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.[5]
Tangeite (synonym: calciovolborthite), CaCuVO4(OH), is closely related.
Volborthite was first described in 1837 for an occurrence in the Sofronovskii Mine, Yugovskii Zavod, Perm, Permskaya Oblast, Middle Urals, Russia.[3]
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.[2]