Quartz is a primary ingredient in sand it is also used to make glass & labware, silica brick, cement, and mortar. Ground quartz is used as an abrasive in stonecutting, sandblasting, and glass grinding. Powdered quartz is used in making porcelain, scouring soaps, sandpaper, and wood fillers. Quartz has a specific gravity of 2.65. In general, the chemical composition of quartz is silicon dioxide (SiO2).