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Chemical Formula | FeCr2O4 |
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Composition | Iron chromium oxide, sometimes with some magnesium. Forms a series with the much rarer Magnesiochromite. |
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Variable Formula | (Fe,Mg)Cr2O4 |
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Color | Brownish-black to greenish-black |
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Streak | Dark brown |
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Hardness | 5½ |
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Crystal Forms and Aggregates |
(Isometric) Crystals, which are octahedral, are rare. More commonly occurs grainy, massive, in veins, as rounded pebbles, in rounded grains, and in nodular blobs embedded in rock. |
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Transparency | Opaque |
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Specific Gravity | 4.2 - 5.0 |
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Luster | Metallic to dull |
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Cleavage | None. May exhibit parting. |
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Fracture | Conchoidal to uneven |
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Tenacity | Brittle |
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Other ID Marks | May be slightly attracted to magnetic fields ("paramagnetic") |
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Other Names |  Cromite, Ferrous
Chromite |
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In Group | Oxides ; Multiple oxides ; Spinel group |
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Uses | Chromite is the main ore of chromium. |
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Striking Features | Streak, hardness, and slight attraction to magnetic fields. |
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Popularity (1-4) | 2 |
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Prevalence (1-3) | 2 |
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Demand (1-3) | 1 |
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Distinguishing Similar Minerals |
Magnetite - has a darker streak Magnesiochromite - has a grayish streak |
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Commonly Occurs With |
Serpentine, Uvarovite, Chlorite, Olivine, Magnetite, Platinum |
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Noteworthy Localities |
There are not many occurrences of
collectible Chromite specimens. Large commercial deposits
exist in Russia, India, Kazakstan, Philippines, New
Caledonia, former Yugoslavia, Zimbabwe, Turkey, Brazil,
and Cuba. Small octahedral crystals occur with Uvarovite in Outokumpu, Finland. In the U.S., Chromite has come from the Bare Hills, near Baltimore, Maryland, and the Wood's Mine, near Texas, Lancaster Co., Pennsylvania. Small crystals also occur with Serpentine in Staten Island (Richmond Co.), New York. Chromite is mined in many areas in California, in the counties of San Luis Obispo, Siskiyou, Fresno, Del Norte, and Glenn. |
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