data_global _chemical_name_mineral 'Beryl' loop_ _publ_author_name 'Aurisicchio C' 'Fioravanti G' 'Grubessi O' 'Zanazzi P F' _journal_name_full 'American Mineralogist' _journal_volume 73 _journal_year 1988 _journal_page_first 826 _journal_page_last 837 _publ_section_title ; Reappraisal of the crystal chemistry of beryl Sample: 22 ; _database_code_amcsd 0001183 _chemical_compound_source 'Mawi mine, Nuristan, Afghanistan' _chemical_formula_sum 'Si6.042 Be2.475 Li.498 Al2 O18 Na.228 Cs.154 Rb.002' _cell_length_a 9.2148 _cell_length_b 9.2148 _cell_length_c 9.2318 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 678.873 _exptl_crystal_density_diffrn 2.756 _symmetry_space_group_name_H-M 'P 6/m c c' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,-x+y,1/2+z' 'x,x-y,1/2-z' '-x+y,-x,-z' 'x-y,x,z' '-y,-x,1/2+z' 'y,x,1/2-z' 'y,-x+y,-z' '-y,x-y,z' 'x-y,-y,1/2+z' '-x+y,y,1/2-z' 'x,y,-z' '-x,-y,z' 'x,x-y,1/2+z' '-x,-x+y,1/2-z' 'x-y,x,-z' '-x+y,-x,z' 'y,x,1/2+z' '-y,-x,1/2-z' '-y,x-y,-z' 'y,-x+y,z' '-x+y,y,1/2+z' 'x-y,-y,1/2-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_U_iso_or_equiv Si1 0.38940 0.11920 0.00000 1.00000 ? Be 0.50000 0.00000 0.25000 0.82500 0.00700 Li 0.50000 0.00000 0.25000 0.16600 0.00700 Si2 0.50000 0.00000 0.25000 0.01400 0.00700 Al 0.66667 0.33333 0.25000 0.99900 ? O1 0.30490 0.23460 0.00000 1.00000 ? O2 0.49830 0.14750 0.14490 1.00000 ? Na 0.00000 0.00000 0.25000 0.22800 ? Cs 0.00000 0.00000 0.25000 0.15400 ? Rb 0.00000 0.00000 0.25000 0.00200 ? loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 Si1 0.00410 0.00410 0.00260 0.00220 0.00000 0.00000 Al 0.00440 0.00440 0.00300 0.00220 0.00000 0.00000 O1 0.01210 0.00900 0.02000 0.00830 0.00000 0.00000 O2 0.01420 0.01380 0.00820 0.00900 -0.00590 -0.00460 Na 0.02470 0.02470 0.01890 0.01235 0.00000 0.00000 Cs 0.02470 0.02470 0.01890 0.01235 0.00000 0.00000 Rb 0.02470 0.02470 0.01890 0.01235 0.00000 0.00000