Zirconium silicate is a colorless tetragonal crystals (when pure); presence of impurities forms various colors; density 4.56 g/cm3; hardness 7.5 Mohs; dissociates to ZrO2 and SiO2 above 1,540°C; melts at 2,550°C; insoluble in water, acids, aqua regia, and alkalies; inert in most chemicals. Zirconium silicate is used as an additive to glass, in ceramic tiles, in ultrafiltration membranes, and as a dental abrasive.