AM_Topaz_5 Formula: Al2 Si O4.42 F1.58 H.42 Name: Topaz Unit cell: 4.657 8.838 8.426 90.0 90.0 90.0 , V=346.80 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: Neutron refinement at T = 10 K