data_global _chemical_name_mineral 'Topaz' loop_ _publ_author_name 'Gatta G D' 'Nestola F' 'Ballaran T B' _journal_name_full 'Physics and Chemistry of Minerals' _journal_volume 33 _journal_year 2006 _journal_page_first 235 _journal_page_last 242 _publ_section_title ; Elastic behaviour and structural evolution of topaz at high pressure Sample: P = .0001 GPa ; _database_code_amcsd 0009026 _chemical_compound_source 'Ouro Preto, Minas Gerias, Brazil' _chemical_formula_sum 'Al2 Si O4 F2' _cell_length_a 4.6627 _cell_length_b 8.8343 _cell_length_c 8.3867 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 345.462 _exptl_crystal_density_diffrn 3.539 _symmetry_space_group_name_H-M 'P b n m' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,y,1/2-z' '-x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' '1/2-x,1/2+y,1/2-z' '1/2-x,1/2+y,z' '1/2+x,1/2-y,-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv Al 0.90470 0.13090 0.08170 0.00530 Si 0.40050 0.94090 0.25000 0.00440 O1 0.79630 0.53210 0.25000 0.00570 O2 0.45310 0.75590 0.25000 0.00350 O3 0.79040 0.01080 0.90690 0.00640 FO 0.90060 0.75330 0.05990 0.01170