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: S2 ; _database_code_amcsd 0001186 _chemical_compound_source 'synthetic, flux-fusion' _chemical_formula_sum 'Si5.97 Al2.008 Be2.97 Cr.052 O18 Na.024' _cell_length_a 9.2051 _cell_length_b 9.2051 _cell_length_c 9.1953 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 674.767 _exptl_crystal_density_diffrn 2.657 _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 Si 0.38730 0.11570 0.00000 0.99500 ? Al1 0.38730 0.11570 0.00000 0.00500 ? Be 0.50000 0.00000 0.25000 0.99000 0.00500 Al2 0.50000 0.00000 0.25000 0.01000 0.00500 Al3 0.66667 0.33333 0.25000 0.97400 ? Cr 0.66667 0.33333 0.25000 0.02600 ? O1 0.31000 0.23660 0.00000 1.00000 ? O2 0.49860 0.14560 0.14530 1.00000 ? Na 0.00000 0.00000 0.25000 0.02400 ? 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 Si 0.00450 0.00400 0.00340 0.00210 0.00000 0.00000 Al1 0.00450 0.00400 0.00340 0.00210 0.00000 0.00000 Al3 0.00390 0.00390 0.00320 0.00195 0.00000 0.00000 Cr 0.00390 0.00390 0.00320 0.00195 0.00000 0.00000 O1 0.01050 0.00850 0.01280 0.00720 0.00000 0.00000 O2 0.00850 0.00640 0.00520 0.00360 -0.00220 -0.00060