| Magnesium Chromite, MgO.Cr2O3, has been obtained by fusion of the mixed oxides. It yields green octahedra harder than quartz and of density 4.415 at 16° C. and 4.6 at 20° C. Several other compounds of magnesium and chromic oxides are known which may be represented by the formulae: MgO.2Cr2O3; 2MgO.Cr2O3; 3MgO.2Cr2O3; 5MgO.4Cr2O3. |