... applications is: silica, hard texture, Mohs hardness of 6, excellent fire resistance and acid resistance, melting point 1730 ° C, the melt ... as an important building block. Gravel for road filled with stone and railway ballast. Sand mixed with asphalt paving, quartz calibration ... abrasive material; quartz sand are mostly used to cut stone, polished glass, grinding the surface of metal products and ...