data_Mg2S
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.11
_cell_length_b   6.11
_cell_length_c   3.66
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2S
_chemical_formula_sum   'Mg4 S2'
_cell_volume   136.8
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Mg  Mg0  1  0.77  0.77  0.0  1.0
  Mg  Mg1  1  0.35  0.35  0.0  1.0
  Mg  Mg2  1  0.83  0.29  0.83  1.0
  Mg  Mg3  1  0.29  0.83  0.83  1.0
  S  S4  1  0.0  0.0  0.0  1.0
  S  S5  1  0.06  0.06  0.83  1.0

data_Mg2S
_symmetry_space_group_name_H-M   Cm
_cell_length_a   8.65
_cell_length_b   8.65
_cell_length_c   3.66
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Mg2S
_chemical_formula_sum   'Mg8 S4'
_cell_volume   273.59
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Mg  Mg0  4  0.06  0.23  0.83  1.0
  Mg  Mg1  2  0.27  0.5  0.0  1.0
  Mg  Mg2  2  0.35  0.0  0.0  1.0
  S  S3  2  0.0  0.0  0.0  1.0
  S  S4  2  0.06  0.0  0.83  1.0

Mg Mg Mg Mg S S
Mg Mg Mg Mg S S 0 4 + + o 1 5 o o - 1 3 o - - 1 3 o o - 1 2 - o - 1 2 o o - 1 4 o o o 2 4 + o + 2 5 + o o 3 4 o + + 3 5 o + o 4 5 o o - 