... sandIt is a hard, wear-resistant, stable chemical properties of silicate minerals, the main mineral composition is SiO2, quartz ... 0.015 % Melting Point: 1750 degree, hardness 7, the relative density of 2.65, can not dissolve in acid, with high fire ... resistance properties. Quartz sand of the main purposes: the manufacture of glass, refractories, smelting ferrosilicon, metallurgical flux, ...