What is Topaz?
{{Infobox mineral | name = Topaz | category = [[Silicate mineral|Nesosilicate]] | boxwidth = | boxbgcolor = | image = Topaze, quartz fumé 1.jpg | imagesize = 270px | caption = Topaz [[crystal]] on matrix | formula = Al<sub>2</sub>SiO<sub>4</sub>(F,OH)<sub>2</sub> | strunz = 9.AF.35 | symmetry = Orthorhombic dipyramidal<br/>[[H-M symbol]]: (2/m 2/m 2/m) <br/>[[Space group]]: Pbnm | unit cell = a = 4.65 Å, b = 8.8 Å, <br/>c = 8.4 Å; Z = 4 | color = Colorless (if no impurities), blue, brown, orange, gray, yellow, green, pink and reddish pink | mohs = 8 (defining mineral) | luster = Vitreous | birefringence = δ = 0.010 | references = <ref>Hurlbut, Cornelius S.; Klein, Cornelis, 1985, ''Manual of Mineralogy'', 20th ed., {{ISBN|0-471-80580-7}}</ref><ref name=Handbook>[http://rruff.geo.arizona.edu/doclib/hom/topaz.pdf Topaz]. Handbook of Mineralogy. (PDF) . Retrieved on 2011-10-29.</ref><ref name=Mindat>[http://www.mindat.org/show.php?id=3996&ld=1&pho= Topaz]. Mindat.org. Retrieved on 2011-10-29.</ref><ref name=Webmineral>[http://webmineral.com/data/Topaz.shtml Topaz]. Webmineral.com. Retrieved on 2011-10-29.</ref> }} '''Topaz''' is a [[silicate mineral]]. Along with [[silicate]], it includes the [[chemical element]]s [[aluminium]] and [[fluorine]] with the [[chemical formula]] [[aluminium|Al]]<sub>2</sub>[[silicon|Si]][[oxygen|O]]<sub>4</sub>([[fluorine|F]],[[hydroxide|OH]])<sub>2</sub>. ==Color and varieties== Pure topaz is colorless and transparent but they usually have colors made by small impurities. The [[wikt:typical|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 [[wikt:precious|precious]] topaz, is the [[tradition]]al November [[birthstone]], the symbol of friendship, and the [[state]] [[gemstone]] for the [[US]] state of [[Utah]].<ref>[http://pioneer.utah.gov/research/utah_symbols/gem.html Utah State Gem – Topaz] {{Webarchive|url=https: