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: 20 ; _database_code_amcsd 0001184 _chemical_compound_source 'Salinas mine, Minas Gerais, Brazil' _chemical_formula_sum 'Si6.021 Be2.496 Li.468 Al2.015 O18 Na.261 Cs.15 Rb.001' _cell_length_a 9.2097 _cell_length_b 9.2097 _cell_length_c 9.2337 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 678.262 _exptl_crystal_density_diffrn 2.758 _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 0.38930 0.11900 0.00000 1.00000 ? Be 0.50000 0.00000 0.25000 0.83200 0.00800 Li 0.50000 0.00000 0.25000 0.15600 0.00800 Si2 0.50000 0.00000 0.25000 0.00700 0.00800 Al1 0.50000 0.00000 0.25000 0.00500 0.00800 Al2 0.66667 0.33333 0.25000 1.00000 ? O1 0.30540 0.23510 0.00000 1.00000 ? O2 0.49800 0.14710 0.14480 1.00000 ? Na 0.00000 0.00000 0.25000 0.26100 ? Cs 0.00000 0.00000 0.25000 0.15000 ? Rb 0.00000 0.00000 0.25000 0.00100 ? 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 0.00450 0.00450 0.00440 0.00240 0.00000 0.00000 Al2 0.00550 0.00550 0.00490 0.00280 0.00000 0.00000 O1 0.01280 0.00920 0.02080 0.00830 0.00000 0.00000 O2 0.01350 0.01420 0.01020 0.00870 -0.00610 -0.00460 Na 0.02290 0.02290 0.01950 0.01145 0.00000 0.00000 Cs 0.02290 0.02290 0.01950 0.01145 0.00000 0.00000 Rb 0.02290 0.02290 0.01950 0.01145 0.00000 0.00000