Important deposit categories: Limestone skarns near granite. Lime-silicate rock layers surrounded by an arrangement of calcium-iron-magnesium-aluminium silicate minerals. Tungsten is usually found in the form of scheelite with a chemical composition of CaWO4 with 80% tungsten (WO3). Scheelite disposes on the extraordinary feature that it is fluorescent under UV light; this makes it easy to discover host rock 1). It occurs as a spotty grain as well as filled in clasts. The concentration of these minerals in usable ore amounts normally to 0.3% to 1% in WO3.The most important tungsten deposits are located in China.
(Source: USGS) 1) Mining Journal – special publication – Tungsten, June, 2008
|
Tungsten deposits |
Metric tons T |
Percentage |
|---|---|---|
| China | 77,000 | 88 |
| Russia | 4,400 | 2 |
| Canada | 2,600 | 3 |
| Africa | 2,000 | 2 |
| Austria | 1,100 | 1 |
| Others | 7,500 | 7 |
| Gesamtproduktion | 89,600 | 100 |