AM_Topaz_2 Formula: Al2 Si O6 H2 Name: Topaz Unit cell: 4.7203 8.9207 8.4189 90.0 90.0 90.0 , V=354.51 Space group: PBNM (62)

Northrup P A , Leinenweber K , Parise J B , American Mineralogist , 79 (1994) p.401-404, The location of H in the high-pressure synthetic Al2SiO4(OH)2 topaz analogue, Sample OH synthetic