... and quantity of impurities, resulting in dyed yellow, orange, red, brown and other colors, hardness 7.8, specific gravity 4.6 ... SiO2 Usage Zircon sand is commonly used in the manufacturing of refractory (Zirconium refractories, such as zirconium corundum brick, ... and enamelware producing, in addition, also used in the production of glass, metal (spongeZr) and zirconium compounds (zirconium dioxide, ...