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| Topaz | |
|---|---|
 Topaz crystal on white matrix | |
| General | |
| Category | Nesosilicate minerals |
| Formula (repeating unit) | Al2SiO4(F,OH)2 |
| IMA symbol | Tpz[1] |
| Strunz classification | 9.AF.35 |
| Crystal system | Orthorhombic |
| Crystal class | 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 | |
| Color | Colorless (if there are no impurities), white, blue, brown, orange, gray, yellow, yellowish brown, green, pink, reddish pink or even red |
| Crystal habit | Prismatic crystal |
| Twinning | Rarely on [111][2] |
| Cleavage | [001] Perfect |
| Fracture | Subconchoidal to uneven |
| Mohs scale hardness | 8 (defining mineral) |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent |
| Specific 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 | Weak in thick sections X = yellow; Y = yellow, violet, reddish; Z = violet, bluish, yellow, pink |
| Ultraviolet fluorescence | Short UV=golden yellow; Long UV=cream |
| References | [3][4][5][6] |
Topaz is a silicate mineral made of aluminum and fluorine with the chemical formula Al2SiO4(F, OH)2. It is used as a gemstone in jewelry and other adornments. Common topaz in its natural state is colorless, though trace element impurities can make it pale blue or golden brown to yellow-orange.[7] Topaz is often treated with heat or radiation to make it a deep blue, reddish-orange, pale green, pink, or purple.[8]
Topaz is a nesosilicate mineral, and more specifically, an aluminosilicate mineral.[9] It is one of the hardest naturally occurring minerals and has a relatively low index of refraction. It has the orthorhombic crystal system and a dipyramidial crystal class.[10]
It occurs in many places in the world. Some of the most popular places where topaz is sourced are Brazil and Russia.[7] Topaz is often mined in open pit or alluvial settings.[11]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Nesse, William D. (2000). Introduction to mineralogy. New York: Oxford University Press. p. 313. ISBN 9780195106916.
- ^ Hurlbut, Cornelius S.; Klein, Cornelis (1985). Manual of Mineralogy (20 ed.). Wiley. ISBN 0-471-80580-7.
- ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1995). "Topaz" (PDF). Handbook of Mineralogy. Vol. II (Silica, Silicates). Chantilly, VA, US: Mineralogical Society of America. ISBN 978-0-9622097-1-0. Retrieved December 5, 2011.
- ^ Topaz. Mindat.org. Retrieved on 2011-10-29.
- ^ Topaz. Webmineral.com. Retrieved on 2011-10-29.
- ^ a b Menzies, Michael A. (2023-12-08). "Connoisseur's Choice: Topaz from Granite Pegmatites: Limoeiro Mine, Virgem da Lapa, Araçuaí Pegmatite District, Minas Gerais, Brazil". Rocks & Minerals. 99 (1): 36–55. doi:10.1080/00357529.2023.2253100. ISSN 0035-7529. S2CID 266145193.
- ^ "Topaz Value, Price, and Jewelry Information". International Gem Society. Retrieved 2021-11-16.
- ^ Tennakoon, Sumudu; Peng, Ye; Mookherjee, Mainak; Speziale, Sergio; Manthilake, Geeth; Besara, Tiglet; Andreu, Luis; Rivera, Fernando (2018-01-22). "Single crystal elasticity of natural topaz at high-temperatures". Scientific Reports. 8 (1): 1372. Bibcode:2018NatSR...8.1372T. doi:10.1038/s41598-017-17856-3. ISSN 2045-2322. PMC 5778148. PMID 29358663.
- ^ Handbook of mineralogy. 2,2: Silica, Silicates: Pt. 2. Tucson, Ariz: Mineral Data Publ. 1995. ISBN 978-0-9622097-1-0.
- ^ "Topaz Mining: Balancing Resource Extraction and Sustainability". www.brilliyond.com. Retrieved 2024-03-20.