Science Fair Project Encyclopedia
|Chemical formula||iron magnesium chromium oxide:(Fe,Mg)Cr2O4|
|Color||Black to brownish black|
|Crystal habit||Octahedral rare; massive to granular|
|Crystal system||Isometric; hexoctahedral|
|Mohs Scale hardness||5.5|
|Refractive index||Subtranslucent to opaque|
|Specific gravity||4.5 - 4.8|
|Other Characteristics||Weakly magnetic|
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.
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