Vanadinite
Vanadinite is a mineral belonging to the apatite group of phosphates, with the chemical formula Pb5(VO4)3Cl. It is one of the main industrial ores of the metal vanadium and a minor source of lead. A dense, brittle mineral, it is usually found in the form of red hexagonal crystals. It is an uncommon mineral, formed by the oxidation of lead ore deposits such as galena. First discovered in 1801 in Mexico, vanadinite deposits have since been unearthed in South America, Europe, Africa, and North America.
| Vanadinite | |
|---|---|
| General | |
| Category | Vanadate minerals Apatite group |
| Formula (repeating unit) | Pb5(VO4)3Cl |
| IMA symbol | Vna |
| Strunz classification | 8.BN.05 |
| Crystal system | Hexagonal |
| Crystal class | Dipyramidal (6/m) H-M symbol: (6/m) |
| Space group | P63/m |
| Unit cell | a = 10.3174, c = 7.3378 [Å]; Z = 2 |
| Identification | |
| Formula mass | 1416.27 g/mol |
| Colour | Bright red, orange-red, red-brown, brown, yellow, whitish, grey or colourless or weakly tinted in transmitted light; pale straw-yellow;. may be concentrically zoned |
| Crystal habit | Prismatic or nodular; may be acicular, hairlike, fibrous; rarely rounded, globular |
| Cleavage | None |
| Fracture | Uneven to conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 3–4 |
| Lustre | Resinous to sub-adamantine |
| Streak | brownish yellow |
| Diaphaneity | Transparent, translucent or opaque |
| Specific gravity | 6.8–7.1 (measured) 6.95 (calculated) |
| Optical properties | Uniaxial (−) |
| Refractive index | nω = 2.416, nε = 2.350 |
| Birefringence | δ = 0.066 |
| Ultraviolet fluorescence | None |
| Melting point | 3,470 °F (1,910 °C) |
| References | |
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