data_1010918
_chemical_name_systematic          'Calcium sulfate hemihydrate'
_chemical_name_mineral             'Bassanite'
_chemical_formula_structural       'Ca S O4 (H2 O).5'
_chemical_formula_sum              'H Ca O4.5 S'
_publ_section_title
;
Ricerche sul solfato di calcio semidrato e sull'anidrite solubile
;
_publ_author_name                  'Gallitelli, P'
_journal_name_full                 'Periodico di Mineralogia'
_journal_coden_ASTM                PEMIA7
_journal_volume                    4
_journal_year                      1933
_journal_page_first                132
_journal_page_last                 171
_cell_length_a                     6.86
_cell_length_b                     6.86
_cell_length_c                     12.7
_cell_angle_alpha                  90
_cell_angle_beta                   90
_cell_angle_gamma                  120
_cell_volume                       517.6
_cell_formula_units_Z              6
_exptl_crystal_density_meas        2.75
_symmetry_space_group_name_H-M     'P 32 2 1 S'
_symmetry_Int_Tables_number        154
_symmetry_cell_setting             trigonal
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  'y,x,2/3-z'
  '-y,x-y,2/3+z'
  '-x,y-x,1/3-z'
  'y-x,-x,1/3+z'
  'x-y,-y,-z'
loop_
_atom_type_symbol
_atom_type_oxidation_number
  Ca2+   2.000
  S6+    6.000
  O2-   -2.000
  H1+    1.000
loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_symmetry_multiplicity
_atom_site_Wyckoff_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_attached_hydrogens
_atom_site_calc_flag
  Ca1   Ca2+   3 b 0. 0.450(1) 0.6667 1.  0 d
  Ca2   Ca2+   3 a 0. 0.450(1) 0.1667 1.  0 d
  S1    S6+    6 c 0.450(1) 0. 0.25 1.  0 d
  O1    O2-    6 c 0.344(3) 0.105(3) 0.317(3) 1.  0 d
  O2    O2-    6 c 0.555(3) -0.105(3) 0.317(3) 1.  0 d
  O3    O2-    6 c 0.271(3) -0.179(3) 0.182(3) 1.  0 d
  O4    O2-    6 c 0.628(3) 0.179(3) 0.182(3) 1.  0 d
  O5    O2-    3 a 0. .000(4) 0.1667 1.  2 d
  H1    H1+    6 c -1. -1. -1. 1.  0 dum