Topaz

Topaz
Topaz crystal on matrix
General
CategoryNesosilicate
Formula
(repeating unit)		Al2SiO4(F,OH)2
Strunz classification9.AF.35
Crystal symmetryOrthorhombic dipyramidal
H-M symbol: (2/m 2/m 2/m)
Space group: Pbnm
Unit cella = 4.65 Å, b = 8.8 Å,
c = 8.4 Å; Z = 4
Identification
ColorColorless (if no impurities), blue, brown, orange, gray, yellow, green, pink and reddish pink
Mohs scale hardness8 (defining mineral)
LusterVitreous
Birefringenceδ = 0.010
References[1][2][3][4]

Topaz is a silicate mineral. Along with silicate, it includes the chemical elements aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2.

Color and varieties

Pure topaz is colorless and transparent but they usually have colors made by small impurities. The typical topaz is wine, yellow, pale gray, reddish-orange, or blue brown. It can also be made white, pale green, blue, gold, or pink (rare).

Orange topaz, also known as precious topaz, is the traditional November birthstone, the symbol of friendship, and the state gemstone for the US state of Utah.[5]

Imperial topaz is yellow, pink (rare, if natural) or pink-orange. Some imperial topaz stones can fade if they are exposed too much in the sunlight.[6][7]

Blue topaz is the US state Texas' gemstone.[8]

Mystic topaz is colorless topaz which has been artificially coated, making it rainbow-colored.[9]

  • Colorless topaz, Minas Gerais, Brazil
    Colorless topaz, Minas Gerais, Brazil
  • A cut blue topaz
    A cut blue topaz
  • A red topaz
    A red topaz
  • Imperial Topaz Gem
    Imperial Topaz Gem
  • Facet Cut Topaz Gemstones in various colors, including mystic.
    Facet Cut Topaz Gemstones in various colors, including mystic.

References

  1. ↑ Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
  2. ↑ Topaz. Handbook of Mineralogy. (PDF) . Retrieved on 2011-10-29.
  3. ↑ Topaz. Mindat.org. Retrieved on 2011-10-29.
  4. ↑ Topaz. Webmineral.com. Retrieved on 2011-10-29.
  5. ↑ Utah State Gem – Topaz Archived 2012-11-14 at the Wayback Machine. Pioneer.utah.gov (2010-06-16). Retrieved on 2011-10-29.
  6. ↑ Imperial Topaz Archived 2009-05-13 at the Wayback Machine, Natural History Museum of Los Angeles County
  7. ↑ Gemstones & Gemology – Topaz Archived 2011-08-08 at the Wayback Machine, Emporia State University
  8. ↑ State Gem – Texas Blue Topaz. State Gemstone Cut – Lone Star Cut. state.tx.us
  9. ↑ Mystic Topaz, Consumer Information. Farlang.com (2008-10-30). Retrieved on 2011-10-29.

Other websites

Wikimedia Commons has media related to Topaz.

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