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: hydrous emerald
;
_database_code_amcsd 0019469
_chemical_compound_source 'Synthetic'
_chemical_formula_sum '(Al1.9 Cr.1) Be3 Si6 O19 H2'
_cell_length_a 9.214
_cell_length_b 9.214
_cell_length_c 9.218
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 677.741
_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
Al   0.66667   0.33333   0.25000   0.95000   0.00608
Cr   0.66667   0.33333   0.25000   0.05000   0.00608
Be   0.50000   0.00000   0.25000   1.00000   0.00304
Si   0.38720   0.11540   0.00000   1.00000   0.00114
O1   0.31060   0.23650   0.00000   1.00000   0.00633
O2   0.49930   0.14560   0.14490   1.00000   0.00329
Wat   0.00000   0.00000   0.25000   1.00000   0.11399