| Material name | Topaz | |||||
| Composition | Al2SiO4(OH)2 | |||||
| Chemical formula weight | 180.06 | |||||
| System | Orthorhombic | |||||
| Temperature (ºC) | r.t. | |||||
| a (Å), b (Å), c (Å) | 4.7203(8) | 8.9207(15) | 8.4189(15) | |||
| α (deg), β (deg), γ (deg) | 90 | 90 | 90 | |||
| Unit cell volume (Å3) | 354.5 | |||||
| Calculated density (g/㎝3) | 3.37 | |||||
| Z | 4 | |||||
| Space group | Pbnm (No.62) | |||||
| atom | site | g | x/a | y/b | z/c | B (Å2) |
| Al | 8d | 1 | 0.90499(8) | 0.13210(5) | 0.07984(6) | 0.33(2) |
| Si | 4c | 1 | 0.40189(10) | 0.94045(7) | 1/4 | 0.29(2) |
| O1 | 4c | 1 | 0.7104(4) | 0.0262(2) | 1/4 | 0.38(4) |
| O2 | 4c | 1 | 0.4439(3) | 0.7561(2) | 1/4 | 0.36(4) |
| O3 | 8d | 1 | 0.2141(2) | 0.9929(1) | 0.0943(1) | 0.38(3) |
| O4 | 8d | 1 | 0.5906(3) | 0.2507(1) | 0.0659(1) | 0.52(3) |
| H1 | 8d | 0.5 | 0.443(11) | 0.199(6) | 0.088(5) | 2.7(12) |
| H2 | 8d | 0.5 | 0.607(14) | 0.281(8) | 0.151(7) | 7.1(23) |
Reference: P.A. Northrup, K. Leinenweber, and J.B. Parise, American Mineralogist, 79, 401 (1994).