Wulfenite
Wulfenite is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes called "yellow lead ore".
| Wulfenite | |
|---|---|
Wulfenite from Red Cloud mine, Arizona | |
| General | |
| Category | Molybdate mineral |
| Formula (repeating unit) | PbMoO4 |
| IMA symbol | Wul |
| Strunz classification | 7.GA.05 |
| Crystal system | Tetragonal |
| Crystal class | Dipyramidal (4/m) H-M symbol: (4/m) |
| Space group | I41/a |
| Unit cell | a = 5.433, c = 12.110 [Å]; Z = 4 |
| Identification | |
| Color | Orange-yellow, yellow, honey-yellow, reddish-orange, rarely colorless, grey, brown, olive-green and even black |
| Crystal habit | Thin tabular to pyramidal |
| Twinning | Twins on the [001] common |
| Cleavage | On {011}, distinct; on {001}, {013}, indistinct |
| Fracture | Irregular to sub-conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 3 |
| Luster | Adamantine, resinous |
| Streak | White |
| Diaphaneity | Transparent to opaque |
| Specific gravity | 6.5–7.0 |
| Optical properties | Uniaxial (−), may be anomalously biaxial |
| Refractive index | nω = 2.405 nε = 2.283 |
| Birefringence | δ = 0.122 |
| Pleochroism | Weak; orange and yellow |
| Ultraviolet fluorescence | None |
| Other characteristics | Specimens may be piezoelectric |
| References | |
It crystallizes in the tetragonal system, often occurring as stubby, pyramidal or tabular crystals. It also occurs as earthy, granular masses. It is found in many localities, associated with lead ores as a secondary mineral associated with the oxidized zone of lead deposits. It is also a secondary ore of molybdenum, and is sought by collectors.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.