Wolframite is a dark-colored, heavy mineral that is one of the main ores of tungsten. It is, in fact, and intermediate between Heubnerite — Manganese Tungstate, MnWO
4, and Ferberite — Iron (II) Tungstate, FeWO
4. Since tungsten is an important constituent in many industrial processes and machine tools, wolframite is very important commercially. It is often associated with the minerals cassiterite, hematite, mica, pyrite, quartz, and tourmaline, and can be found as longitudinally striated crystals, columns, and massive forms. The primary producer is China; however, it is also extracted in Colorado and other parts of the United States, as well as Russia, Korea, England, and Bolivia. It has a sub-metallic to resinous luster and a brown to black streak.
| Chemical Composition: |
Iron Manganese Tungstate (Fe,Mn)WO4 |
| Color: |
Black, Gray, or Brown |
| Hardness: |
4 - 4.5 |
| Cleavage: |
Perfect in one direction |
| Fracture: |
Uneven |
| Crystal Structure: |
Transparent to opaque; monoclinic |
| Specific Gravity: |
7.0 - 7.5 |
| Luster: |
Sub-metallic to resinous |
| Streak: |
Brown to black |
| Occurence: |
China, Colorado and SW USA; Russia, Korea, England, and Bolivia |
