data_9001104
_chemical_name 'Bertrandite'
loop_
_publ_author_name
'Downs J W'
'Ross F K'
_journal_name_full "American Mineralogist"
_journal_volume 72
_journal_year 1987
_journal_page_first 979
_journal_page_last 983
_publ_section_title
;
 Neutron-diffraction study of bertrandite
 Note: O2y has been corrected
;
_chemical_formula_sum 'Si2 Be4 H2 O9'
_cell_length_a 8.7135
_cell_length_b 15.268
_cell_length_c 4.5683
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 607.756
_symmetry_space_group_name_H-M 'C m c 21'
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  '1/2+x,1/2+y,z'
  'x,-y,1/2+z'
  '1/2+x,1/2-y,1/2+z'
  '-x,y,z'
  '1/2-x,1/2+y,z'
  '-x,-y,1/2+z'
  '1/2-x,1/2-y,1/2+z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
Si   0.32510   0.11410   0.65400
Be1   0.17260   0.05249   0.15620
Be2   0.32640   0.22023   0.15090
H1   0.00000   0.20060   0.42030
H2   0.50000   0.36750   0.45300
O1   0.28990   0.12430   0.00000
O2   0.20950   0.04300   0.50650
O3   0.29380   0.20910   0.50120
O4   0.50000   0.08470   0.59160
O5   0.50000   0.25530   0.08770
O6   0.00000   0.08760   0.09780