An isometric mineral, 8(FeCr₂O₄) ; spinel group; dimorphous with donathite; forms crystal-solution series with magnesiochromite in the chromite series of the spinel group, and with hercynite; rarely occurs as a pure end member. End-member chromite contains 68% Cr₂O₃, but natural minerals do not commonly exceed 50%. Occurs in metallic black octahedral crystals; weakly to moderately ferrimagnetic; an accessory in, or layers in, mafic and ultramafic rocks; also in black sands, the major source of chromium.