Quartz has electrical properties and heat resistance that make it valuable in electronic products. Its luster, color, and diaphaneity make it useful as a gemstone and also in the making of glass.
Quartz sand is used in the production of container glass, flat plate glass, specialty glass, and fiberglass. The high hardness of quartz, seven on the Mohs Scale, makes it harder than most other natural substances. As such it is an excellent abrasive material. Quartz sands and finely ground silica sand are used for sand blasting, scouring cleansers, grinding media, and grit for sanding and sawing.
Quartz is very resistant to both chemicals and heat. It is therefore often used as a foundry sand. Quartz sand has a high resistance to being crushed. In the petroleum industry, sand slurries are forced down oil and gas wells under very high pressures in a process known as hydraulic fracturing.
Quartz sand is used as a filler in the manufacture of rubber, paint, and putty. Screened and washed, carefully sized quartz grains are used as filter media and roofing granules. Quartz sands are used for traction in the railroad and mining industries. A wide variety of uses have also been developed for optical-grade quartz crystals. They are used to make specialized lenses, windows and filters used in lasers, microscopes, telescopes, electronic sensors, and scientific instruments.