Wolframite
Wolframite is an iron, manganese, and tungstate mineral with a chemical formula of (Fe,Mn)WO4 that is the intermediate mineral between ferberite (Fe2+ rich) and hübnerite (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.
| Wolframite | |
|---|---|
| General | |
| Category | Oxide minerals |
| Formula (repeating unit) | (Fe,Mn)WO4 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | P2/c |
| Unit cell | a = 4.77 Å, b = 5.73 Å c = 4.98 Å; β = 90.2°; Z = 2 |
| Identification | |
| Color | Grayish to brownish black |
| Crystal habit | Tabular to short prismatic crystals |
| Cleavage | Perfect {010} |
| Fracture | Uneven to rough |
| Mohs scale hardness | 4–4.5 |
| Luster | Submetallic to resinous |
| Streak | Reddish brown |
| Diaphaneity | Opaque |
| Specific gravity | 7–7.5 |
| Fusibility | 3–4 to magnetic globule |
| References | |
This mineral was historically found in Europe in Bohemia, Saxony, and in the UK in Devon and Cornwall. China reportedly has the world's largest supply of tungsten ore with about 60%. Other producers are Spain, Canada, Portugal, Russia, Australia, Thailand, South Korea, Rwanda, Bolivia, the United States, and the Democratic Republic of the Congo.