| Ferric tellurite occurs in nature as the mineral durdenite in Honduras, associated with metallic tellurium. Hardness 2 to 2.5. Its chemical composition closely approaches that represented by the formula Fe2O3.3TeO2.4H2O, or Fe(TeO3)3.4H2O. Emmonsite is another naturally occurring ferric tellurite found in Colorado as yellowish green scales, associated with lead carbonate and quartz. |