AM_Topaz_3 Formula: Al2 Si O4 F2 Name: Topaz Unit cell: 4.6601 8.826 8.3778 90.0 90.0 90.0 , V=344.58 Space group: PBNM (62)

Diego Gatta G , Nestola F , Bromiley G D , Loose A , American Mineralogist , 91 (2006) p.1839-1846, 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