C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
C03C1/02—Pretreated ingredients
C03C1/022—Purification of silica sand or other minerals