Topaz

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Topaz
180xp
A group o topaz creestals on matrix
General
Category Nesosilicate meenerals
Formula
(repeatin unit)
Al2SiO4(F,OH)2
Strunz clessification 9.AF.35
Creestal seestem Orthorhombic
Creestal cless Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Pbnm
Unit cell a = 4.65 Å, b = 8.8 Å,
c = 8.4 Å; Z = 4
Identification
Colour Colourless (if na impurities), blue, broun, orange, gray, yellae, green, pink an reiddish pink
Creestal habit Prismatic creestals wi faces striatit parallel tae lang dimension; an aa columnar, compact, massive
Cleavage [001] Perfect
Fractur Subconchoidal tae uneven
Mohs scale haurdness 8 (definin meeneral)
Skinkle Vitreous
Streak White
Diaphaneity Transparent
Speceefic gravity 3.49–3.57
Optical properties Biaxial (+)
Refractive index nα = 1.606–1.629
nβ = 1.609–1.631
nγ = 1.616–1.638
Birefringence δ = 0.010
Pleochroism Waik in thick sections X = yellae; Y = yellae, violet, reiddish; Z = violet, bluish, yellae, pink
Ultraviolet fluorescence Short UV=gowden yellae; Lang UV=cream
References [1][2][3][4]

Topaz is a silicate meeneral o aluminium an fluorine wi the chemical formula Al2SiO4(F,OH)2. Topaz creestallises in the orthorhombic seestem, an its creestals are maistly prismatic terminatit bi pyramidal an ither faces.

References[eedit | eedit soorce]

  1. Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
  2. Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1995). "Topaz". Handbook of Mineralogy (PDF). II (Silica, Silicates). Chantilly, VA, US: Mineralogical Society of America. ISBN 978-0-9622097-1-0. Retrieved December 5, 2011. 
  3. Topaz. Mindat.org. Retrieved on 2011-10-29.
  4. Topaz. Webmineral.com. Retrieved on 2011-10-29.