data_global
_chemical_name_mineral 'Gypsum'
loop_
_publ_author_name
'Schofield P F'
'Knight K S'
'Stretton I C'
_journal_name_full 'American Mineralogist'
_journal_volume 81 
_journal_year 1996
_journal_page_first 847
_journal_page_last 851
_publ_section_title
;
 Thermal expansion of gypsum investigated by neutron powder diffraction
 T = 4.2 K
;
_chemical_formula_sum 'Ca S O6 D4'
_cell_length_a 5.6740
_cell_length_b 15.1049
_cell_length_c 6.4909
_cell_angle_alpha 90
_cell_angle_beta 118.513
_cell_angle_gamma 90
_cell_volume 488.829
_exptl_crystal_density_diffrn      2.394
_symmetry_space_group_name_H-M 'I 1 2/a 1'
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  '1/2+x,1/2+y,1/2+z'
  '-x,y,1/2-z'
  '1/2-x,1/2+y,-z'
  '1/2+x,-y,z'
  '+x,1/2-y,1/2+z'
  '1/2-x,-y,1/2-z'
  '-x,1/2-y,-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_U_iso_or_equiv
Ca   0.50000   0.07996   0.25000   0.00124
S   0.00000   0.07667   0.75000   0.00132
O1   0.96413   0.13282   0.55028   0.00376
O2   0.75763   0.02194   0.66427   0.00355
Ow   0.38342   0.17240   0.46179   0.00403
D1   0.25369   0.16662   0.50769   0.01809
D2   0.40549   0.24481   0.49322   0.01631

