There are currently over 50 types of chromium containing minerals discovered in nature, which belong to the categories of oxides, chromates, and silicates. In addition, there are a few hydroxides, iodates, nitrides, and sulfides. Chromium nitride and chromium sulfide minerals are only found in meteorites. Chromium minerals with industrial value belong to the category of chromium spinel minerals, and their chemical formula is (Mg, Fe2+) (Cr, Al, Fe3+) 2O4 or (Mg, Fe2+) O (Cr, Al, Fe3+) 2O3, with a Cr2O3 content of 18% to 62%.
