Quartz, widely distributed mineral of many varieties that consists primarily of silica, or silicon dioxide (SiO2). Minor impurities such as lithium, sodium, potassium, and titanium may be present. Quartz has attracted attention from the earliest times; water-clear crystals were known to the ancient Greeks as krystallos—hence the name crystal,
Cras consequat aliquet quam, ut pretium massa elementum vel. Sed nibh lacus, gravida non tellus pharetra, molestie faucibus dui. Vivamus ac finibus elit. Maecenas quis magna lorem. Nullam hendrerit scelerisque magna, vitae sollicitudin ipsum tempus at. Suspendisse feugiat luctus massa ut consequat. Mauris lacinia eget est id dapibus.
Quartz has great economic importance. Many varieties are gemstones, including amethyst, citrine, smoky quartz, and rose quartz. Sandstone, composed mainly of quartz, is an important building stone. Large amounts of quartz sand (also known as silica sand) are used in the manufacture of glass and ceramics and for foundry molds in metal casting. Crushed quartz is used as an abrasive in sandpaper, silica sand is employed in sandblasting, and sandstone is still used whole to make whetstones, millstones, and grindstones. Silica glass (also called fused quartz) is used in optics to transmit ultraviolet light. Tubing and various vessels of fused quartz have important laboratory applications, and quartz fibers are employed in extremely sensitive weighing devices.
