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| Formula: | SiO2 | 
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| Crystal: | Hexagonal | |||
| Hardness: | 7 | |||
| Spec. Gr.: | 2.65 | |||
| Streak: | White | |||
| Cleavage: | Rarely Observed | |||
| Location: | Tiefengletscher, Switzerland |
| Quartz, the commonest of all minerals, forms twelve percent of the Earth's crust. Stone Age primeval man used flint, a variety of quartz, to make weapons. Crystallized quartz occurs in many colors: clear, white (rock crystal), black (marion), pink (rose), purple (amethyst) and brown (smoky). Smoky quartz has a smoky brown color and is found associated with rock crystal in pegmatites, ore veins, and minerals of the Alpine paragenesis. An enormous crystal chamber in the Zinggenstock west of the Grimsel Pass, Switzerland, was entered by Strahlers (prospectors) in 1719 who took out 50,000 kg of rock crystal and smoky quartz crystals, individuals of which weighed up to 500 kg. Swiss smoky quartz crystals are incredibly sharp and clear. Most prized are the Gwindel (twisted crystals), many of which come from the Tiefengletscher near Andermatt, Switzerland. The Gwindel crystal in the UCSB Geology collection is exceptionally fine. |
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Bibliography: Weibel, Max, Die Mineralism der Schweiz, 1996, pg. 38-42, 133. Bancroft, Peter, Gem and Crystal Treasures, 1984, pg. 386-390. |
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