data_global
_chemical_name_mineral 'Beryl'
loop_
_publ_author_name
'Gibbs G V'
'Breck D W'
'Meagher E P'
_journal_name_full 'Lithos'
_journal_volume 1 
_journal_year 1968
_journal_page_first 275
_journal_page_last 285
_publ_section_title
;
 Structural refinement of hydrous and anhydrous synthetic beryl,
 Al2(Be3Si6)O18 and emerald, Al1.9Cr0.1(Be3Si6)O18
 Note: anhydrous beryl
;
_database_code_amcsd 0019466
_chemical_compound_source 'Synthetic'
_chemical_formula_sum 'Al2 Be3 Si6 O18'
_cell_length_a 9.212
_cell_length_b 9.212
_cell_length_c 9.187
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 675.169
_exptl_crystal_density_diffrn      2.644
_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_U_iso_or_equiv
Al   0.66667   0.33333   0.25000   0.00380
Be   0.50000   0.00000   0.25000   0.00342
Si   0.38750   0.11590   0.00000   0.00266
O1   0.31090   0.23750   0.00000   0.00697
O2   0.49920   0.14620   0.14500   0.00469