data_global
_chemical_name_mineral 'Norbergite'
loop_
_publ_author_name
'Gibbs G V'
'Ribbe P H'
_journal_name_full 'American Mineralogist'
_journal_volume 54 
_journal_year 1969
_journal_page_first 376
_journal_page_last 390
_publ_section_title
;
 The crystal structures of the humite minerals: I. Norbergite
;
_database_code_amcsd 0000190
_chemical_formula_sum 'Mg3 Si O4.2 (F1.8 H.2)'
_cell_length_a 4.7104
_cell_length_b 10.2718
_cell_length_c 8.7476
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 423.246
_exptl_crystal_density_diffrn      3.179
_symmetry_space_group_name_H-M 'P b n m'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  'x,y,1/2-z'
  '-x,-y,1/2+z'
  '1/2+x,1/2-y,1/2+z'
  '1/2-x,1/2+y,1/2-z'
  '1/2-x,1/2+y,z'
  '1/2+x,1/2-y,-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
Mg1   0.98900   0.63300   0.43050   1.00000   0.00418
Mg2   0.99240   0.90770   0.25000   1.00000   0.00481
Si   0.41950   0.71960   0.25000   1.00000   0.00355
O1   0.76170   0.72040   0.25000   1.00000   0.00481
O2   0.27930   0.57400   0.25000   1.00000   0.00405
O3   0.26900   0.79070   0.10340   1.00000   0.00405
F   0.72950   0.96820   0.08340   0.90000   0.00937
O-H   0.72950   0.96820   0.08340   0.10000   0.00937