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|System:||Orthorhombic||Colour:||Colourless, white, pale ...|
|Name:||Named after Topasos Island in the Red Sea. In antique times, the name was probably used for the gemstone that is now known as Peridot.|
Occurs in pegmatites and high-temperature quartz veins, also in cavities in granites and rhyolites.
A maximum of ~30 % of the F site is occupied by OH in natural topaz, although in some very rare cases OH-dominant members have been described, see Unnamed (OH-analogue of Topaz) (Zhang et al., 2002). A pure synthetic OH analogue of topaz has been synthesised (Wunder et al., 1993).
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Classification of Topaz
|IMA status:||Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"|
|Strunz 8th edition ID:||8/B.02-70|
|Nickel-Strunz 10th (pending) edition ID:||9.AF.35|
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in ,  and/or only  coordination
|Dana 8th edition ID:||220.127.116.11|
52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
3 : Insular SiO4 Groups and O, OH, F, and H2O with cations in  coordination only
|Hey's CIM Ref.:||17.2.1|
17 : Silicates Containing other Anions
2 : Silicates with fluoride
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Occurrences of Topaz
|Geological Setting:||As a rock forming mineral in igneous rocks, pegmatites and rhyolites, hydrothermal veins, metamorphic rocks and greisens.|
Physical Properties of Topaz
|Diaphaneity (Transparency):||Transparent, Translucent|
|Colour:||Colourless, white, pale blue, light green, yellow, yellowish brown, or red|
|Hardness Data:||Mohs hardness reference species|
|Density (measured):||3.4 - 3.6 g/cm3|
Crystallography of Topaz
|Class (H-M):||mmm (2/m 2/m 2/m) - Dipyramidal|
|Cell Parameters:||a = 4.65Å, b = 8.8Å, c = 8.4Å|
|Ratio:||a:b:c = 0.528 : 1 : 0.955|
|Unit Cell Volume:||V 343.73 Å³ (Calculated from Unit Cell)|
|Morphology:||Long to short prismatic.|
|Comment:||Crystallography (orthorhomic or triclinic) depends upon the ratio of F and OH in the mineral.|
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Edge Lines | Miller Indicies | Axes
Opaque | Translucent | Transparent
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
|X-Ray Powder Diffraction:|
Radiation - Copper Kα
Data courtesy of RRUFF project at University of Arizona, used with permission.
|X-Ray Powder Diffraction:|
Optical Data of Topaz
|RI values:||nα = 1.606 - 1.629 nβ = 1.609 - 1.631 nγ = 1.616 - 1.638|
|2V:||Measured: 48° to 68°, Calculated: 58° to 68°|
|Maximum Birefringence:||δ = 0.010|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
|Dispersion:||noticable r > v|
|Comments:||In thick sections|
Y= yellow, violet, reddish
Z= violet, bluish, yellow, pink
Chemical Properties of Topaz
|Simplified for copy/paste:||Al2(SiO4)(F,OH)2|
|Essential elements:||Al, F, O, Si|
|All elements listed in formula:||Al, F, H, O, Si|
Relationship of Topaz to other Species
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Topaz
|Fluorescence in UV light:||Rarely yellow, white, orange, greenish-yellow|
Display Requirements from:
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Topaz
Klaproth, M.H. (1810): Chemische Unmtersuchung des Pycnits, Beiträge zur chemischen Kenntniss der Mineralkörper, Fünfter Band, Rottmann Berlin, 50-57
Parise, J.B., Cuff, C., and Moore, F.H. (1980) A neutron diffraction study of topaz: evidence for lower symmetry. Mineralogical Magazine: 43: 943.
B. Wunder, D. C. Rubie, C. R. Ross II, O. Medenbach, F. Seifert & W. Schreyer (1993): Synthesis, stability, and properties of Al2SiO4(OH)2: a fully hydrated analogue of topaz. American Mineralogist, 78, 285–297.
E. E. Foord, L. L. Jackson, J. E. Taggart, J. G. Crock & T. V. V. King (1995): Topaz: environment of crystallization, crystal chemistry, and infrared spectra. Mineralogical Record, 26, 69–71.
Mineralogical Record (1995): 26: 5.
Holfert, J., Mroch, W., and Fuller, J. (1996) A Field Guide to Topaz and Associated Minerals of the Thomas Range, Utah (Topaz Mountain) 1. HM Publishing, Cypress, California.
Extra Lapis No. 13 (1997).
Shinoda, K. and Aikawa, N. (1997) IR active orientation of OH bending mode in topaz. Physics and Chemistry of Minerals: 24: 551-554.
R. Y. Zhang, J. G. Liou & J. F. Shu (2002): Hydroxyl-rich topaz in high-pressure and ultrahigh-pressure kyanite quartzites, with retrograde woodhouseite, from the Sulu terrane, eastern China. American Mineralogist, 87, 445–453. [Topaz with 35-55% substitution of F by OH]
Komatsu, K., Kagi H., Okada, T., Kuribayashi, T., Parise, J.B., and Kudoh, Y. (2005) Pressure dependence of the OH-stretching mode in F-rich natural topaz and topaz-OH. American Mineralogist: 90: 266-270.
Topaz - Perfect Cleavage (2011) Extra Lapis English vol 14. 100p
Mindat.org articles about Topaz
Best Localities for Topaz
|Best of Species:||Topaz|
Internet Links for Topaz
|Specimens:||The following Topaz specimens are currently listed for sale on minfind.com.|
Localities for Topaz
The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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Locality Updated: Iron Quadrangle, Minas Gerais, BrazilFrom Amir C. Akhavan, 19th Sep 2014 09:20:00