Mineral description : Chromite

Small grains of chromite in serpentine from Horsmanaho, Finland.

Mineral class Oxides : Chromite group.
Chemical formula (Fe,Mg)Cr2O4
Crystal system Cubic.
Habitus Crystals octahedral, but very rare. Often as granular, nodular or massive.
Cleavage None, uneven fracture.
Hardness 5.5
Density 4.5-4.8
Color Black to brownish black.
Streak Dark brown streak.
Luster Metallic.
Description Chromite is an important ore for chromium.
Occurance Forms in ultrabasic and igneous rocks, often in serpentine rocks.
Associates Serpentine, olivine.
Notes Insoluble in acids, infusible in a flame and weakly magnetic.
Locations A relatively rare mineral in Sweden, but some scattered occurances exists in the caledonides.
  • Frostviken, Jämtland. As magmatic veins in olivine.
  • Horsmanaho Finland. As small grains in a serpentine rock.

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Last changed : 1998-03-07