. . . "olybdenum oxides, nickel oxides, vanadium oxides, tungsten oxides, and rare-earth metal oxides, and similar compounds, and consisting of compounds such as carbonate, sulfate, and hydroxide, and similar compounds transformable into oxides after a heat treatment, and also consisting of clay minerals such as dolomite, talc, and kaolinite, and similar clay minerals, and also consisting of double oxide" .