Topaz

''This article is about the mineral or gemstone, for other uses see: Topaz (disambiguation).'' The mineral topaz is a silicate of aluminium and fluorine with the chemical formula (AlF)₂SiO₄. It is orthorhombic and its crystals are mostly prismatic terminated by pyramidal and other faces, the basal pinacoid often being present. It has an easy and perfect basal cleavage and so gemstones or other fine specimens should be handled with care to avoid developing cleavage flaws. The fracture is conchoidal to uneven. Topaz has a Mohs scale of mineral hardness of 8, a specific gravity of 3.4-3.6, and a vitreous lustre. Pure topaz is transparent but is usually tinted by impurities; typical topaz is wine or straw-yellow. They may also be white, gray (color), green, blue, or reddish-yellow and transparent or translucent. When heated, yellow topaz often becomes reddish-pink. It can also be irradiated, turning the stone a light and distinctive shade of blue. Topaz is found associated with the more acid rocks of the granite and rhyolite type and may be found with fluorite and cassiterite. It can be found in the Ural mountains and Ilmen mountains mountains, Czech Republic, Saxony, Norway, Sweden, Japan, Brazil, Mexico, and the United States. The name "topaz" is derived from the Greek language ''topazos'', "to seek," which was the name of an island in the Red Sea that was difficult to find and from which a yellow stone (now believed to be a yellowish olivine) was mined in ancient times. In the Middle Ages the name topaz was used to refer to any yellow gemstone, but now the name is only properly applied to the silicate described above. Topaz is also the birthstone of November. *''See also:'' List of minerals Gemstones Silicate minerals

Topaz

Joined on May 18th, 2004. My [http://www.topazstorm.com website].

Topaz

Hello Topaz! User:Nighthawk4211 04:57, Dec 2, 2004 (UTC)

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Words begining with Topaz:

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ToPAz3in6
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TopazLJF
Topazolite
Topaz_(1945_film)
Topaz_(1945_movie)
Topaz_(1969_movie)
Topaz_(1969_movie)
Topaz_(disambiguation)
Topaz_(movie)
Topaz_Kitsune
Topaz_Road_National_Park