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Topaz

This page kindly sponsored by Norman King
Formula:
Al2(SiO4)(F,OH)2
System:
Orthorhombic
Colour:
Colourless, white, pale ...
Lustre:
Vitreous
Hardness:
8
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).

Visit gemdat.org for gemological information about Topaz.

Classification of Topaz

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
9.AF.35

9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
52.3.1.1

52 : NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
3 : Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] coordination only
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

Vitreous
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Colourless, white, pale blue, light green, yellow, yellowish brown, or red
Streak:
White
Hardness (Mohs):
8
Hardness Data:
Mohs hardness reference species
Tenacity:
Brittle
Cleavage:
Perfect
(001)
Fracture:
Irregular/Uneven, Sub-Conchoidal
Density:
3.4 - 3.6 g/cm3 (Measured)    

Crystallography of Topaz

Crystal System:
Orthorhombic
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 ų (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.

Crystallographic forms of Topaz

Crystal Atlas:
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Topaz no.188 - Goldschmidt (1913-1926)
Topaz no.208 - Goldschmidt (1913-1926)
Topaz no.215 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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Crystal Structure

Structure
Reference
Diego Gatta G Nestola F Bromiley G D Loose A (2006) New insight into crystal chemistry of topaz: a multi-methodological study Locality: Ouro Preto, Minas Gerias, Brazil Sample: X-ray refinement at T = 298 K Note: x(F4) corrected. American Mineralogist 91:1839-1846.

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More Crystal Structures
Click here to view more crystal structures at the American Mineralogist Crystal Structure Database
X-Ray Powder Diffraction:
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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction Data:
d-spacingIntensity
3.693 (60)
3.195 (66)
3.037 (37)
2.937 (100)
2.3609 (45)
2.1049 (44)
1.6706 (27)

Optical Data of Topaz

Type:
Biaxial (+)
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°
Max Birefringence:
δ = 0.010
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
noticable r > v
Pleochroism:
Weak
Comments:
In thick sections

X= yellow
Y= yellow, violet, reddish
Z= violet, bluish, yellow, pink

Chemical Properties of Topaz

Formula:
Al2(SiO4)(F,OH)2
Essential elements:
All elements listed in formula:

Relationship of Topaz to other Species

9.AF.05SillimaniteAl2(SiO4)O
9.AF.10AndalusiteAl2(SiO4)O
9.AF.10KanonaiteMn3+Al(SiO4)O
9.AF.15KyaniteAl2(SiO4)O
9.AF.20MulliteAl4+2xSi2-2xO10-x
9.AF.20Krieselite(Al,Ga)2(GeO4)(OH)2
9.AF.23BoromulliteAl9BSi2O19
9.AF.25YoderiteMg(Al,Fe3+)3(SiO4)2O(OH)
9.AF.30Magnesiostaurolite(Mg,Li,Fe2+)1.5-2Al9(SiO4)4O6(OH)2
9.AF.30Staurolite(Fe2+,Mg,Zn)1.5-2Al9(SiO4)4O6(OH,O)2
9.AF.30Zincostaurolite(Zn,Li,Fe2+,Mg)1.5-2Al9(SiO4)4O6(OH)2
9.AF.40NorbergiteMg3(SiO4)(F,OH)2
9.AF.45AlleghanyiteMn52+(SiO4)2(OH)2
9.AF.45Chondrodite(Mg,Fe2+)5(SiO4)2(F,OH)2
9.AF.45ReinhardbraunsiteCa5(SiO4)2(OH,F)2
9.AF.45KumtyubeiteCa5(SiO4)2F2
9.AF.45HydroxylchondroditeMg5(SiO4)2(OH)2
9.AF.50Humite(Mg,Fe2+)7(SiO4)3(F,OH)2
9.AF.50Manganhumite(Mn2+,Mg)7(SiO4)3(OH)2
9.AF.50Unnamed (Ca-analogue of Humite)Ca7(SiO4)4F2
9.AF.55ClinohumiteMg9(SiO4)4F2
9.AF.55SonoliteMn92+(SiO4)4(OH,F)2
9.AF.55HydroxylclinohumiteMg9(SiO4)4(OH)2
9.AF.60LeucophoeniciteMn72+(SiO4)3(OH)2
9.AF.65Ribbeite(Mn2+,Mg)5(SiO4)2(OH)2
9.AF.70JerrygibbsiteMn92+(SiO4)4(OH)2
9.AF.75FranciscaniteMn62+(V5+,☐)2(SiO4)2(O,OH)6
9.AF.75ÖrebroiteMn32+(Sb5+,Fe3+)(SiO4)(O,OH)3
9.AF.75WeliniteMn62+(W6+,Mg)2(SiO4)2(O,OH)6
9.AF.80EllenbergeriteMg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10
9.AF.85Chloritoid(Fe2+,Mg,Mn2+)Al2(SiO4)O(OH)2
9.AF.85MagnesiochloritoidMgAl2(SiO4)O(OH)2
9.AF.85Ottrélite(Mn2+,Fe2+,Mg)Al2(SiO4)O(OH)2
9.AF.90PoldervaartiteCaCa[SiO3(OH)](OH)
9.AF.90OlmiiteCaMn2+[SiO3(OH)](OH)
17.2.2PolylithioniteKLi2Al(Si4O10)(F,OH)2
17.2.3Leifite(Na,H2O)Na6[Be2Al2(Al,Si)Si15O39]F2
17.2.5Meliphanite(Ca,Na)2(Be,Al)[Si2O6(OH,F)]
17.2.6SarcoliteNa2Ca12(Ca,K,Fe,Sr,Mg)2Al8Si12(P,Si)O52F2
17.2.7GötzeniteNa2Ca5Ti(Si2O7)2F4
17.2.8Kuliokite-(Y)Y4Al(SiO4)2(OH)2F5
17.2.9ZinnwalditeKLiFe2+Al(AlSi3O10)(F,OH)2
17.2.10MagbasiteKBaFe3+Mg7Si8O22(OH)2F6

Other Names for Topaz

Name in Other Languages:
Arabic:زبرجد
Basque:Topazio
Bosnian (Latin Script):Topaz
Bulgarian:Топаз
Croatian:Topaz
Czech:Topaz
Danish:Topas
Dutch:Topaas
Estonian:Topaas
Finnish:Topaasi
French:Topaze
German:Topas
Hebrew:טופז
Hungarian:Topáz
Italian:Topazio
Japanese:トパーズ
Korean:황옥
Lithuanian:Topazas
Norwegian (Bokmål):Topas
Polish:Topaz
Portuguese:Topázio
Romanian:Topaz
Russian:Топаз
Simplified Chinese:黄玉
托帕石
Slovak:Topás
Slovenian:Topaz
Spanish:Topacio
Traditional Chinese:黃玉
托帕石
Turkish:Topaz
Ukrainian:Топаз

Other Information

Rarely yellow, white, orange, greenish-yellow
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Gemstone

References for Topaz

Reference List:
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

Internet Links for Topaz

Specimens:
The following Topaz specimens are currently listed for sale on minfind.com.

Localities for Topaz

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.
Mineral and/or Locality  
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