data_global
_chemical_name_mineral 'Beryl'
loop_
_publ_author_name
'Sherriff B L'
'Grundy H D'
'Hartman J S'
'Hawthorne F C'
'Cerny P'
_journal_name_full 'The Canadian Mineralogist'
_journal_volume 29 
_journal_year 1991
_journal_page_first 271
_journal_page_last 285
_publ_section_title
;
 The incorporation of alkalis in beryl: multi-nuclear MAS NMR
 and crystal-structure study
 Sample: BLM503
;
_database_code_amcsd 0005260
_chemical_compound_source 'Bernic Lake, Manitoba, Canada'
_chemical_formula_sum 'Si6 Be2.7 Li.62 Al2 O18 Na.19 Cs.11'
_cell_length_a 9.210
_cell_length_b 9.210
_cell_length_c 9.230
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 678.034
_exptl_crystal_density_diffrn      2.734
_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   0.38900   0.11850   0.00000   1.00000   0.00420
Be   0.50000   0.00000   0.25000   0.90000   0.00880
Li   0.50000   0.00000   0.25000   0.10000   0.00880
Al   0.66667   0.33333   0.25000   1.00000   0.00520
O1   0.30600   0.23540   0.00000   1.00000   0.01170
O2   0.49820   0.14690   0.14480   1.00000   0.01030
Na   0.00000   0.00000   0.00000   0.19000   0.02170
Li   0.00000   0.00000   0.00000   0.32000   0.02170
Cs   0.00000   0.00000   0.25000   0.11000   0.03670