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| Topaz | |
|---|---|
 Topaz crystal on matrix | |
| General | |
| Category | Nesosilicate |
| Formula (repeating unit) | Al2SiO4(F,OH)2 |
| Strunz classification | 9.AF.35 |
| Crystal symmetry | Orthorhombic dipyramidal 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 no impurities), blue, brown, orange, gray, yellow, green, pink and reddish pink |
| Mohs scale hardness | 8 (defining mineral) |
| Luster | Vitreous |
| Birefringence | δ = 0.010 |
| References | |
Topaz is a silicate mineral. Along with silicate, it includes the chemical elements aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2.
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