The crystal structure described by Fe7S8 crystallizes in the trigonal P3_121 space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one S(4), two equivalent S(1), and two equivalent S(3) atoms. In the second Fe site, Fe(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms to form a mixture of distorted edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 50-51°. In the third Fe site, Fe(3) is bonded to one S(1), one S(4), two equivalent S(2), and two equivalent S(3) atoms to form a mixture of distorted edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 44-60°. In the fourth Fe site, Fe(4) is bonded to two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms to form a mixture of distorted edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 50-60°. In the fifth Fe site, Fe(5) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms to form a mixture of distorted edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 44-60°. There are four inequivalent S sites. In the first S site, S(4) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(4), and one Fe(5) atom. In the second S site, S(1) is bonded in a 5-coordinate geometry to one Fe(2), one Fe(3), one Fe(5), and two equivalent Fe(1) atoms. In the third S site, S(2) is bonded in a 5-coordinate geometry to one Fe(2), one Fe(4), one Fe(5), and two equivalent Fe(3) atoms. In the fourth S site, S(3) is bonded in a 5-coordinate geometry to one Fe(4), two equivalent Fe(1), and two equivalent Fe(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe7S8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.582
_cell_length_b   6.582
_cell_length_c   15.567
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   584.058
_cell_formula_units_Z   3
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
  Fe  Fe0  1  0.410  0.425  0.147  1.0
  Fe  Fe1  1  0.083  0.000  0.333  1.0
  Fe  Fe2  1  0.015  0.590  0.813  1.0
  Fe  Fe3  1  0.483  0.948  0.015  1.0
  Fe  Fe4  1  0.000  0.439  0.167  1.0
  Fe  Fe5  1  0.439  0.000  0.833  1.0
  Fe  Fe6  1  0.590  0.015  0.187  1.0
  Fe  Fe7  1  0.000  0.019  0.167  1.0
  Fe  Fe8  1  0.575  0.985  0.480  1.0
  Fe  Fe9  1  0.425  0.410  0.853  1.0
  Fe  Fe10  1  0.917  0.917  0.000  1.0
  Fe  Fe11  1  0.052  0.535  0.348  1.0
  Fe  Fe12  1  0.465  0.517  0.681  1.0
  Fe  Fe13  1  0.985  0.575  0.520  1.0
  Fe  Fe14  1  0.981  0.981  0.500  1.0
  Fe  Fe15  1  0.000  0.083  0.667  1.0
  Fe  Fe16  1  0.517  0.465  0.319  1.0
  Fe  Fe17  1  0.561  0.561  0.500  1.0
  Fe  Fe18  1  0.948  0.483  0.985  1.0
  Fe  Fe19  1  0.535  0.052  0.652  1.0
  Fe  Fe20  1  0.019  0.000  0.833  1.0
  S  S21  1  0.216  0.852  0.428  1.0
  S  S22  1  0.346  0.212  0.586  1.0
  S  S23  1  0.352  0.650  0.246  1.0
  S  S24  1  0.148  0.364  0.762  1.0
  S  S25  1  0.298  0.648  0.913  1.0
  S  S26  1  0.702  0.350  0.420  1.0
  S  S27  1  0.350  0.702  0.580  1.0
  S  S28  1  0.654  0.866  0.747  1.0
  S  S29  1  0.636  0.784  0.095  1.0
  S  S30  1  0.134  0.788  0.081  1.0
  S  S31  1  0.648  0.298  0.087  1.0
  S  S32  1  0.852  0.216  0.572  1.0
  S  S33  1  0.707  0.826  0.397  1.0
  S  S34  1  0.866  0.654  0.253  1.0
  S  S35  1  0.788  0.134  0.919  1.0
  S  S36  1  0.826  0.707  0.603  1.0
  S  S37  1  0.364  0.148  0.238  1.0
  S  S38  1  0.119  0.293  0.064  1.0
  S  S39  1  0.784  0.636  0.905  1.0
  S  S40  1  0.293  0.119  0.936  1.0
  S  S41  1  0.174  0.881  0.731  1.0
  S  S42  1  0.212  0.346  0.414  1.0
  S  S43  1  0.650  0.352  0.754  1.0
  S  S44  1  0.881  0.174  0.269  1.0
[/CIF]
.
The crystal structure described by Fe7S8 crystallizes in the trigonal P3_121 space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one S(4), two equivalent S(1), and two equivalent S(3) atoms. In the second Fe site, Fe(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms to form a mixture of distorted edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 50-51°. In the third Fe site, Fe(3) is bonded to one S(1), one S(4), two equivalent S(2), and two equivalent S(3) atoms to form a mixture of distorted edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 44-60°. In the fourth Fe site, Fe(4) is bonded to two equivalent S(2), two equivalent S(3), and two equivalent S(4) atoms to form a mixture of distorted edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 50-60°. In the fifth Fe site, Fe(5) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms to form a mixture of distorted edge, face, and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 44-60°. There are four inequivalent S sites. In the first S site, S(4) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(4), and one Fe(5) atom. In the second S site, S(1) is bonded in a 5-coordinate geometry to one Fe(2), one Fe(3), one Fe(5), and two equivalent Fe(1) atoms. In the third S site, S(2) is bonded in a 5-coordinate geometry to one Fe(2), one Fe(4), one Fe(5), and two equivalent Fe(3) atoms. In the fourth S site, S(3) is bonded in a 5-coordinate geometry to one Fe(4), two equivalent Fe(1), and two equivalent Fe(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe7S8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.582
_cell_length_b   6.582
_cell_length_c   15.567
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   584.058
_cell_formula_units_Z   3
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
  Fe  Fe0  1  0.410  0.425  0.147  1.0
  Fe  Fe1  1  0.083  0.000  0.333  1.0
  Fe  Fe2  1  0.015  0.590  0.813  1.0
  Fe  Fe3  1  0.483  0.948  0.015  1.0
  Fe  Fe4  1  0.000  0.439  0.167  1.0
  Fe  Fe5  1  0.439  0.000  0.833  1.0
  Fe  Fe6  1  0.590  0.015  0.187  1.0
  Fe  Fe7  1  0.000  0.019  0.167  1.0
  Fe  Fe8  1  0.575  0.985  0.480  1.0
  Fe  Fe9  1  0.425  0.410  0.853  1.0
  Fe  Fe10  1  0.917  0.917  0.000  1.0
  Fe  Fe11  1  0.052  0.535  0.348  1.0
  Fe  Fe12  1  0.465  0.517  0.681  1.0
  Fe  Fe13  1  0.985  0.575  0.520  1.0
  Fe  Fe14  1  0.981  0.981  0.500  1.0
  Fe  Fe15  1  0.000  0.083  0.667  1.0
  Fe  Fe16  1  0.517  0.465  0.319  1.0
  Fe  Fe17  1  0.561  0.561  0.500  1.0
  Fe  Fe18  1  0.948  0.483  0.985  1.0
  Fe  Fe19  1  0.535  0.052  0.652  1.0
  Fe  Fe20  1  0.019  0.000  0.833  1.0
  S  S21  1  0.216  0.852  0.428  1.0
  S  S22  1  0.346  0.212  0.586  1.0
  S  S23  1  0.352  0.650  0.246  1.0
  S  S24  1  0.148  0.364  0.762  1.0
  S  S25  1  0.298  0.648  0.913  1.0
  S  S26  1  0.702  0.350  0.420  1.0
  S  S27  1  0.350  0.702  0.580  1.0
  S  S28  1  0.654  0.866  0.747  1.0
  S  S29  1  0.636  0.784  0.095  1.0
  S  S30  1  0.134  0.788  0.081  1.0
  S  S31  1  0.648  0.298  0.087  1.0
  S  S32  1  0.852  0.216  0.572  1.0
  S  S33  1  0.707  0.826  0.397  1.0
  S  S34  1  0.866  0.654  0.253  1.0
  S  S35  1  0.788  0.134  0.919  1.0
  S  S36  1  0.826  0.707  0.603  1.0
  S  S37  1  0.364  0.148  0.238  1.0
  S  S38  1  0.119  0.293  0.064  1.0
  S  S39  1  0.784  0.636  0.905  1.0
  S  S40  1  0.293  0.119  0.936  1.0
  S  S41  1  0.174  0.881  0.731  1.0
  S  S42  1  0.212  0.346  0.414  1.0
  S  S43  1  0.650  0.352  0.754  1.0
  S  S44  1  0.881  0.174  0.269  1.0
[/CIF]
.