data_global _chemical_name_mineral 'Phenakite' loop_ _publ_author_name 'Downs J W' 'Gibbs G V' _journal_name_full 'American Mineralogist' _journal_volume 72 _journal_year 1987 _journal_page_first 769 _journal_page_last 777 _publ_section_title ; An exploratory examination of the electron density and electrostatic potential of phenakite ; _database_code_amcsd 0001110 _chemical_formula_sum 'Si Be2 O4' _cell_length_a 12.472 _cell_length_b 12.472 _cell_length_c 8.251 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 1111.500 _exptl_crystal_density_diffrn 2.961 _symmetry_space_group_name_H-M 'R -3' loop_ _space_group_symop_operation_xyz 'x,y,z' '2/3+x,1/3+y,1/3+z' '1/3+x,2/3+y,2/3+z' 'y,-x+y,-z' '2/3+y,1/3-x+y,1/3-z' '1/3+y,2/3-x+y,2/3-z' '-x+y,-x,z' '2/3-x+y,1/3-x,1/3+z' '1/3-x+y,2/3-x,2/3+z' '-x,-y,-z' '2/3-x,1/3-y,1/3-z' '1/3-x,2/3-y,2/3-z' '-y,x-y,z' '2/3-y,1/3+x-y,1/3+z' '1/3-y,2/3+x-y,2/3+z' 'x-y,x,-z' '2/3+x-y,1/3+x,1/3-z' '1/3+x-y,2/3+x,2/3-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Si 0.19562 0.98402 0.74990 Be1 0.19430 0.98410 0.41560 Be2 0.19410 0.98220 0.08460 O1 0.20975 0.12125 0.75030 O2 0.33382 0.00040 0.74991 O3 0.12223 0.91217 0.91497 O4 0.12228 0.91342 0.58495 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 0.00350 0.00300 0.00300 0.00141 0.00005 0.00014 Be1 0.00520 0.00550 0.00480 0.00260 -0.00050 0.00030 Be2 0.00450 0.00560 0.00530 0.00230 -0.00010 0.00000 O1 0.00750 0.00420 0.00360 0.00370 0.00000 -0.00030 O2 0.00270 0.00440 0.00590 0.00170 -0.00020 -0.00030 O3 0.00430 0.00470 0.00350 0.00140 0.00030 0.00010 O4 0.00400 0.00470 0.00350 0.00100 -0.00020 -0.00030