Magnesiochromite

Chromite-Magnesiochromite Series and Magnesiochromite-Spinel Series. It forms a complete solid solution series with many other members of the group. It is the magnesium analogue of zincochromite, cochromite, manganochromite and chromite and the Cr analogue of spinel and magnesioferrite. It usually contains ferrous iron [Fe(II)], ferric iron [Fe(III)], and Al. "Ferritchromite", i.e. Fe(III) substitutions for Al and Cr, usually in grain rims, may give high total Fe and a false chromite identification, whereas Fe(II) > Mg is the actual deciding factor in the species designation for chromite. Magnesiochromite is about twice as common as chromite. Much of the mineral referred to as "chromite" in geological and petrological papers and mining statistics is magnesiochromite. The Fe-dominant species chromite may be subordinate to magnesiochromite in many "chromite" deposits, chromitites, and other "chromite"-bearing rocks. Note: Near end-member chromite has a higher specific gravity than near end-member magnesiochromite.