Topaz
Topaz | |
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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]
- ↑ Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0-471-80580-7
- ↑ 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 5 December 2011.
- ↑ Topaz. Mindat.org. Retrieved on 2011-10-29.
- ↑ Topaz. Webmineral.com. Retrieved on 2011-10-29.