Chromite
Chromite (Iron Chromium Oxide)
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, iron magnesium chromium oxide: (Fe,Mg)Cr₂O₄, is an oxide mineral belonging to the spinel group. Magnesium is always present in variable amounts, also aluminium and iron substitute for chromium.

Chromite is found in peridotite and other layered ultramafic intrusive rocks and also found in metamorphic rocks such as serpentinites. Ore deposites of chromite form as early magmatic differentiates. It is commonly associated with olivine, magnetite, serpentine, and corundum. Chromite is the chief ore of chromium.

References and external links

• Dana's Manual of Mineralogy ISBN 0471032883
• Mineral Galleries: Chromite (http://mineral.galleries.com/minerals/oxides/chromite/chromite.htm)
• Webmineral.com (http://webmineral.com/data/Chromite.shtml)
• Minerals.net (http://www.minerals.net/mineral/oxides/chromite/chromite.htm)

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