QUARTZ

The word "quartz" is derived from the German word "quarz" and its Middle High German ancestor "twarc", which probably originated in Slavic (cf. Czech tvrdý ("hard"), Polish twardy ("hard")).Quartz ,which is of Slavic origin (Czech miners called it křemen). Other sources attribute the word's origin to the Saxon word Querkluftertz, meaning cross-vein ore.

Quartz is the most common material identified as the mystical substance maban in Australian Aboriginal mythology. It is found regularly in passage tomb cemeteries in Europe in a burial context, such as Newgrange or Carrowmore in the Republic of Ireland. The Irish word for quartz is grian cloch, which means 'stone of the sun'. Quartz was also used in Prehistoric Ireland, as well as many other countries, for stone tools; both vein quartz and rock crystal were knapped as part of the lithic technology of the prehistoric peoples.

Macrocrystalline varieties
Rock crystal Clear, colorless
Amethyst Purple, transparent
Citrine Yellow to reddish orange to brown, greenish yellow Prasiolite Mint green, transparent

Rose quartz Pink, translucent
Rutilated quartz Contains acicular (needles) inclusions of rutile milky quartz White, translucent to opaque

Quartz throughout history

Roman naturalist Pliny the Elder believed quartz to be water ice, permanently frozen after great lengths of time. (The word "crystal" comes from the Greek wordκρύσταλλος, "ice".) He supported this idea by saying that quartz is found near glaciers in the Alps, but not on volcanic mountains, and that large quartz crystals were fashioned into spheres to

cool the hands. He also knew of the ability of quartz to split light into a spectrum. This idea persisted until at least the 17th century.

In the 17th century, Nicolas Steno's study of quartz paved the way for modern crystallography. He discovered that no matter how distorted a quartz crystal, the long prism faces always made a perfect 60° angle.

Charles B. Sawyer invented the commercial quartz crystal manufacturing process in Cleveland, Ohio, United States. This initiated the transition from mined and cut quartz for electrical appliances to manufactured quartz.

Smoky quartz Brown to gray, opaque
Also Chalcedony is a cryptocrysta line form of silica consisting of fine intergrowths of both quartz, and its monoclinic polymorph moganite.

Other opaque gemstone varieties of quartz, or mixed rocks including quartz, often including contrasting bands or patterns of color, are agate, onyx, carnelian, and jasper.