Chromite
Encyclopedia : C : CH : CHR : Chromite
| Chromite | |
|---|---|
| |
| General | |
| Category | Mineral |
| Chemical formula | iron magnesium chromium oxide:(Fe,Mg)Cr2O4 |
| Identification | |
| Color | Black to brownish black |
| Crystal habit | Octahedral rare; massive to granular |
| Crystal system | Isometric; hexoctahedral |
| Cleavage | absent |
| Fracture | Conchoidal |
| Mohs Scale hardness | 5.5 |
| Luster | Submetallic |
| Refractive index | Subtranslucent to opaque |
| Pleochroism | N/A |
| Streak | Dark brown |
| Specific gravity | 4.5 - 4.8 |
| Fusibility | Infusable |
| Solubility | ? |
| Other Characteristics | Weakly magnetic |
| Major varieties | |
| Magnesiochromite | |
Chromite is found in peridotite and other layered ultramafic intrusive rocks and also found in metamorphic rocks such as serpentinites. Ore deposits of chromite form as early magmatic differentiates. It is commonly associated with olivine, magnetite, serpentine, and corundum. The vast Bushveld igneous complex of South Africa is a large layered mafic to ultramafic igneous body with some layers consisting of 90% chromite making the rare rock type, chromitite. Chromite is the chief ore of chromium.
Chromite is also used as a refractory material.
Chromite is found in Afghanistan, Iran, Pakistan, Oman, Zimbabwe.
In Pakistan Chromite has been mined in the Zhob District of Baluchistan since 1902. Currently the major mining company in Pakistan is Pakistan Chrome Mines Ltd. Chromite is found in the ultramfic rocks in the Zhob District of Baluchistan, Most of the Chromite is of metalurgical grade with Cr2O3 averaging 46% and a chrome to iron ration of 3:1.
References and external links
- Dana's Manual of Mineralogy ISBN 0471032883
- Guilbert, John M., and Park, Charles F., Jr. (1986) The Geology of Ore Deposits, Freeman, ISBN 0-7167-1456-6
- [Mineral Galleries: Chromite]
- [Webmineral.com]
- [Minerals.net]
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