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Chemical Formula | MgCr2O4 |
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Composition | Magnesium chromium oxide, sometimes with some iron. Forms a series with Chromite. |
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Variable Formula | (Mg,Fe)Cr2O4 |
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Color | Black to brownish-black |
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Streak | Dark gray |
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Hardness | 5½ |
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Crystal Forms and Aggregates |
(Isometric) Crystals, which are octahedral, are extremely rare. Usually occurs grainy, massive, and as rounded embedded masses. |
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Transparency | Opaque |
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Specific Gravity | 4.2 |
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Luster | Metallic to dull |
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Cleavage | None |
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Fracture | Conchoidal to uneven |
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Tenacity | Brittle |
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Other Names |  Picrochromite |
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In Group | Oxides ; Multiple oxides ; Spinel group |
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Striking Features | Streak and hardness |
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Popularity | 3 |
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Prevalence | 3 |
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Demand | 3 |
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Distinguishing Similar Minerals |
Chromite - has a brownish streak, slightly attracted to magnetic fields |
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Commonly Occurs With |
Chromite, Serpentine, Chlorite, Magnetite |
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Noteworthy Localities |
Cedar Mountain Ridge Chromite deposit, near Livermore, Alameda Co., California |
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Picture Icon Links |
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Picture Links | Sorry. No Images currently available. |
