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