Wulfenite
| Wulfenite | |
|---|---|
Wulfenite from Mexico
|
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| General | |
| Category | Molybdate mineral |
|
Formula (repeating unit) |
PbMoO4 |
| 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 | |
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".
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.
Wulfenite was first described in 1845 for an occurrence in Bad Bleiberg, Carinthia, Austria. It was named for Franz Xavier von Wulfen (1728–1805), an Austrian mineralogist.
It occurs as a secondary mineral in oxidized hydrothermal lead deposits. It occurs with cerussite, anglesite, smithsonite, hemimorphite, vanadinite, pyromorphite, mimetite, descloizite, plattnerite and various iron and manganese oxides.
A noted locality for wulfenite is the Red Cloud Mine in Arizona. Crystals are deep red in color and usually very well-formed. The Los Lamentos locality in Mexico produced very thick tabular orange crystals.
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Wikipedia