The word "quartz" is derived from the German word "Quarz", which had the same form in the first half of the 14th century in Middle High German and in East Central Germanand which came from the Polish dialect term kwardy, which

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Quartz belongs to the trigonal crystal system at room temperature, and to the hexagonal crystal system above 573 °C (846 K; 1,063 °F). The

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Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent, and has often been used for hardstone carvings, such as the Lothair Crystal

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Quartz is a defining constituent of granite and other felsic igneous rocks. It is very common in sedimentary rocks such as sandstone

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Quartz is extracted from open pit mines. Miners occasionally use explosives to expose deep pockets of quartz. More frequently, bulldozers and backhoesare used to remove soil and

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Tridymite and cristobalite are high-temperature polymorphs of SiO2 that occur in high-silica volcanic rocks. Coesiteis a denser polymorph of SiO2 found in some meteorite impact sites and in metamorphic rocks formed at pressures greater than those typical

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Not all varieties of quartz are naturally occurring. Some clear quartz crystals can be treated using heat or gamma-irradiationto induce color where it would not otherwise have occurred

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