Wolframite
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| Wolframite | |
|---|---|
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| General | |
| Category | Mineral |
| Chemical formula | (Fe,Mn)WO4 |
| Identification | |
| Color | Black (ferberite) to brown (huebnerite) |
| Crystal habit | Tabular crystals, sometimse prismatic |
| Crystal system | Monoclinic 2/m |
| Cleavage | Perfect 010 |
| Fracture | Uneven to rough |
| Mohs Scale hardness | 4-4.5 |
| Luster | Submetallic to resinous |
| Refractive index | Opaque |
| Pleochroism | None |
| Streak | Black to brown |
| Specific gravity | 7 - 7.5 |
| Fusibility | 3 - 4 to magnetic globule |
| Solubility | insoluble |
Wolframite (Fe,Mn)WO4, is an iron manganese tungstate mineral that is the intermediate between ferberite (Fe2+ rich) and huebernite (Mn2+ rich). Along with scheelite, the wolframite series are the most important tungsten ore minerals. Wolframite is found in quartz veins and pegmatites associated with granitic intrusives. Associated minerals include cassiterite, scheelite, bismuth, quartz, pyrite, galena, sphalerite, and arsenopyrite.
It was historically found in Bohemia, Saxony, and Cornwall. China reportedly has the world's largest supply of tungsten ore with about 60%. Other producers are Portugal, Russia, Australia, Thailand, Korea, Bolivia, and the United States.
The name comes from German Wolfram for tungsten and provides the chemical symbol, W, for tungsten.
Before depleted uranium began to be used instead, wolframite was highly valued as the main source of the metal tungsten, a strong and high inertia material with many military uses. In WWII wolframite mines were a strategic asset as the metal was used to make tank armour.
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