This page will contain external links about Topaz, as they become available.

Topaz

This article is about the mineral or gemstone, for other uses see: Topaz (disambiguation).

Topaz 4 Carat Oval Shape Topaz Gemstone Ring Enhanced with Azotic(r)Treatment Heart Cut Sky Blue Topaz Ring

The mineral topaz is a silicate of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2. It crystallizes in the orthorhombic system 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 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, 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. A recent trend in jewelry is the manufacture of topaz specimens that display iridescent colors, by applying a thin layer of titanium oxide via physical vapor deposition.

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 and Ilmen mountains, Czech Republic, Saxony, Norway, Sweden, Japan, Brazil, Mexico, and the United States.

Etymology and historical/mythical usage

The name "topaz" is derived from the Greek 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.

According to Rebbenu Bachya, the word "Leshem" in the verse Exodus 28:19 means "Topaz" and was the stone on the Ephod representing the tribe of Dan.

Topaz is also the birthstone of November.

Example of Heat Treated Topaz-Pink Topaz Pear Cut Ring

References

  • Webmineral
  • Mindat with location data
  • Mineral galleries

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Topaz is also the birthstone of November. Cotton Stage and Theatre curtains should be checked with an open flame every 5 to 7 years after manufacture to ensure continued flame resistance. According to Rebbenu Bachya, the word "Leshem" in the verse Exodus 28:19 means "Topaz" and was the stone on the Ephod representing the tribe of Dan. Cotton Velour is treated with chemicals to render it flame resistant when used in this application. 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. Velours used for this range from 16oz per linear yard to 32oz per linear yard. The name "topaz" is derived from the Greek 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. Velour is also widely used in the manufacture of Stage and Theatre drapery.

It can be found in the Ural and Ilmen mountains, Czech Republic, Saxony, Norway, Sweden, Japan, Brazil, Mexico, and the United States. One of the leading velour commission dye-houses in Europe is the company RG Textil Technik GbmH in Burscheid, Germany. Topaz is found associated with the more acid rocks of the granite and rhyolite type and may be found with fluorite and cassiterite. It's featured in spandex fetishism. A recent trend in jewelry is the manufacture of topaz specimens that display iridescent colors, by applying a thin layer of titanium oxide via physical vapor deposition. Velour is used in dancewear for the ease of movement it affords, and is also popular for warm, colorful casual clothing. It can also be irradiated, turning the stone a light and distinctive shade of blue. It combines the stretchy properties of knits such as spandex with the rich appearance and feel of velvet.

When heated, yellow topaz often becomes reddish-pink. Velour is a textile, a knitted counterpart of velvet. They may also be white, gray, green, blue, or reddish-yellow and transparent or translucent. Pure topaz is transparent but is usually tinted by impurities; typical topaz is wine or straw-yellow. Topaz has a hardness of 8, a specific gravity of 3.4-3.6, and a vitreous lustre.

The fracture is conchoidal to uneven. 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. It crystallizes in the orthorhombic system and its crystals are mostly prismatic terminated by pyramidal and other faces, the basal pinacoid often being present. The mineral topaz is a silicate of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2.

This article is about the mineral or gemstone, for other uses see: Topaz (disambiguation).. Mineral galleries. Mindat with location data. Webmineral.

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