Real Dictionary

quartz
Quartz is a mineral in the form of a hard, shiny crystal. It is used in making electronic equipment and very accurate watches and clocks.

quartz in American English
any of various crystallized forms of silica that are transparent, translucent, or colored, used in many ways, esp. as a gem or in making glass, lenses, or quartz crystals
noun: one of the commonest minerals, silicon dioxide, SiO2, having many varieties that differ in color, luster, etc., and occurring either in masses (as agate, bloodstone, chalcedony, jasper, etc.) or in crystals (as rock crystal, amethyst, citrine, etc.): the

quartz in British English
noun: a colourless mineral often tinted by impurities, found in igneous, sedimentary, and metamorphic rocks. It is used in the manufacture of glass, abrasives, and cement, and also as a gemstone; the violet-purple variety is amethyst, the brown variety is cairn