The crystal structure described by Fe7S8 crystallizes in the trigonal P3_1 space group. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one S(1), one S(3), one S(4), one S(5), one S(6), and one S(7) atom to form a mixture of face, corner, and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 55-56°. In the second Fe site, Fe(2) is bonded to one S(2), one S(3), one S(4), one S(5), one S(6), and one S(8) atom to form a mixture of distorted face, corner, and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 54-56°. In the third Fe site, Fe(3) is bonded to one S(1), one S(2), one S(4), one S(5), one S(7), and one S(8) atom to form a mixture of distorted corner and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. In the fourth Fe site, Fe(4) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(3), one S(6), one S(7), and one S(8) atom. In the fifth Fe site, Fe(5) is bonded to one S(1), one S(3), one S(4), one S(5), one S(6), and one S(8) atom to form a mixture of face and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(4), one S(5), one S(7), and one S(8) atom. In the seventh Fe site, Fe(7) is bonded in a 6-coordinate geometry to one S(2), one S(3), one S(4), one S(6), one S(7), and one S(8) atom. There are eight inequivalent S sites. In the first S site, S(5) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(5), and one Fe(6) atom. In the second S site, S(6) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(4), one Fe(5), and one Fe(7) atom. In the third S site, S(7) is bonded in a distorted pentagonal planar geometry to one Fe(1), one Fe(3), one Fe(4), one Fe(6), and one Fe(7) atom. In the fourth S site, S(8) is bonded in a 6-coordinate geometry to one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), and one Fe(7) atom. In the fifth S site, S(1) is bonded to one Fe(1), one Fe(3), one Fe(4), one Fe(5), and one Fe(6) atom to form a mixture of distorted corner and edge-sharing SFe5 trigonal bipyramids. In the sixth S site, S(2) is bonded in a distorted pentagonal planar geometry to one Fe(2), one Fe(3), one Fe(4), one Fe(6), and one Fe(7) atom. In the seventh S site, S(3) is bonded to one Fe(1), one Fe(2), one Fe(4), one Fe(5), and one Fe(7) atom to form a mixture of distorted corner and edge-sharing SFe5 trigonal bipyramids. In the eighth S site, S(4) is bonded in a 6-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(5), one Fe(6), and one Fe(7) atom. is represented by the CIF card [CIF]
data_Fe7S8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.645
_cell_length_b   6.645
_cell_length_c   15.774
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   603.183
_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  0.479  0.472  0.180  1.0
  Fe  Fe1  1  0.528  0.007  0.513  1.0
  Fe  Fe2  1  0.993  0.521  0.846  1.0
  Fe  Fe3  1  0.433  0.963  0.162  1.0
  Fe  Fe4  1  0.037  0.470  0.496  1.0
  Fe  Fe5  1  0.530  0.567  0.829  1.0
  Fe  Fe6  1  0.012  0.962  0.162  1.0
  Fe  Fe7  1  0.038  0.050  0.496  1.0
  Fe  Fe8  1  0.950  0.988  0.829  1.0
  Fe  Fe9  1  0.010  0.542  0.154  1.0
  Fe  Fe10  1  0.458  0.468  0.487  1.0
  Fe  Fe11  1  0.532  0.990  0.821  1.0
  Fe  Fe12  1  0.527  0.002  0.334  1.0
  Fe  Fe13  1  0.998  0.525  0.668  1.0
  Fe  Fe14  1  0.475  0.473  0.001  1.0
  Fe  Fe15  1  0.952  0.000  0.325  1.0
  Fe  Fe16  1  1.000  0.952  0.658  1.0
  Fe  Fe17  1  0.048  0.048  0.992  1.0
  Fe  Fe18  1  0.955  0.430  0.320  1.0
  Fe  Fe19  1  0.570  0.525  0.653  1.0
  Fe  Fe20  1  0.475  0.045  0.986  1.0
  S  S21  1  0.164  0.330  0.091  1.0
  S  S22  1  0.670  0.834  0.424  1.0
  S  S23  1  0.166  0.836  0.757  1.0
  S  S24  1  0.159  0.834  0.066  1.0
  S  S25  1  0.166  0.325  0.399  1.0
  S  S26  1  0.675  0.841  0.733  1.0
  S  S27  1  0.645  0.326  0.089  1.0
  S  S28  1  0.674  0.319  0.422  1.0
  S  S29  1  0.681  0.355  0.756  1.0
  S  S30  1  0.643  0.804  0.089  1.0
  S  S31  1  0.196  0.839  0.422  1.0
  S  S32  1  0.161  0.357  0.755  1.0
  S  S33  1  0.317  0.143  0.255  1.0
  S  S34  1  0.857  0.174  0.588  1.0
  S  S35  1  0.826  0.683  0.921  1.0
  S  S36  1  0.314  0.649  0.248  1.0
  S  S37  1  0.351  0.664  0.582  1.0
  S  S38  1  0.336  0.686  0.915  1.0
  S  S39  1  0.819  0.647  0.252  1.0
  S  S40  1  0.353  0.171  0.585  1.0
  S  S41  1  0.829  0.181  0.918  1.0
  S  S42  1  0.806  0.140  0.229  1.0
  S  S43  1  0.860  0.666  0.562  1.0
  S  S44  1  0.334  0.194  0.896  1.0
[/CIF]
.
The crystal structure described by Fe7S8 crystallizes in the trigonal P3_1 space group. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one S(1), one S(3), one S(4), one S(5), one S(6), and one S(7) atom to form a mixture of face, corner, and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 55-56°. In the second Fe site, Fe(2) is bonded to one S(2), one S(3), one S(4), one S(5), one S(6), and one S(8) atom to form a mixture of distorted face, corner, and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 54-56°. In the third Fe site, Fe(3) is bonded to one S(1), one S(2), one S(4), one S(5), one S(7), and one S(8) atom to form a mixture of distorted corner and edge-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. In the fourth Fe site, Fe(4) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(3), one S(6), one S(7), and one S(8) atom. In the fifth Fe site, Fe(5) is bonded to one S(1), one S(3), one S(4), one S(5), one S(6), and one S(8) atom to form a mixture of face and corner-sharing FeS6 octahedra. The corner-sharing octahedral tilt angles range from 48-57°. In the sixth Fe site, Fe(6) is bonded in a 6-coordinate geometry to one S(1), one S(2), one S(4), one S(5), one S(7), and one S(8) atom. In the seventh Fe site, Fe(7) is bonded in a 6-coordinate geometry to one S(2), one S(3), one S(4), one S(6), one S(7), and one S(8) atom. There are eight inequivalent S sites. In the first S site, S(5) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(5), and one Fe(6) atom. In the second S site, S(6) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(2), one Fe(4), one Fe(5), and one Fe(7) atom. In the third S site, S(7) is bonded in a distorted pentagonal planar geometry to one Fe(1), one Fe(3), one Fe(4), one Fe(6), and one Fe(7) atom. In the fourth S site, S(8) is bonded in a 6-coordinate geometry to one Fe(2), one Fe(3), one Fe(4), one Fe(5), one Fe(6), and one Fe(7) atom. In the fifth S site, S(1) is bonded to one Fe(1), one Fe(3), one Fe(4), one Fe(5), and one Fe(6) atom to form a mixture of distorted corner and edge-sharing SFe5 trigonal bipyramids. In the sixth S site, S(2) is bonded in a distorted pentagonal planar geometry to one Fe(2), one Fe(3), one Fe(4), one Fe(6), and one Fe(7) atom. In the seventh S site, S(3) is bonded to one Fe(1), one Fe(2), one Fe(4), one Fe(5), and one Fe(7) atom to form a mixture of distorted corner and edge-sharing SFe5 trigonal bipyramids. In the eighth S site, S(4) is bonded in a 6-coordinate geometry to one Fe(1), one Fe(2), one Fe(3), one Fe(5), one Fe(6), and one Fe(7) atom. is represented by the CIF card [CIF]
data_Fe7S8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.645
_cell_length_b   6.645
_cell_length_c   15.774
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   603.183
_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  0.479  0.472  0.180  1.0
  Fe  Fe1  1  0.528  0.007  0.513  1.0
  Fe  Fe2  1  0.993  0.521  0.846  1.0
  Fe  Fe3  1  0.433  0.963  0.162  1.0
  Fe  Fe4  1  0.037  0.470  0.496  1.0
  Fe  Fe5  1  0.530  0.567  0.829  1.0
  Fe  Fe6  1  0.012  0.962  0.162  1.0
  Fe  Fe7  1  0.038  0.050  0.496  1.0
  Fe  Fe8  1  0.950  0.988  0.829  1.0
  Fe  Fe9  1  0.010  0.542  0.154  1.0
  Fe  Fe10  1  0.458  0.468  0.487  1.0
  Fe  Fe11  1  0.532  0.990  0.821  1.0
  Fe  Fe12  1  0.527  0.002  0.334  1.0
  Fe  Fe13  1  0.998  0.525  0.668  1.0
  Fe  Fe14  1  0.475  0.473  0.001  1.0
  Fe  Fe15  1  0.952  0.000  0.325  1.0
  Fe  Fe16  1  1.000  0.952  0.658  1.0
  Fe  Fe17  1  0.048  0.048  0.992  1.0
  Fe  Fe18  1  0.955  0.430  0.320  1.0
  Fe  Fe19  1  0.570  0.525  0.653  1.0
  Fe  Fe20  1  0.475  0.045  0.986  1.0
  S  S21  1  0.164  0.330  0.091  1.0
  S  S22  1  0.670  0.834  0.424  1.0
  S  S23  1  0.166  0.836  0.757  1.0
  S  S24  1  0.159  0.834  0.066  1.0
  S  S25  1  0.166  0.325  0.399  1.0
  S  S26  1  0.675  0.841  0.733  1.0
  S  S27  1  0.645  0.326  0.089  1.0
  S  S28  1  0.674  0.319  0.422  1.0
  S  S29  1  0.681  0.355  0.756  1.0
  S  S30  1  0.643  0.804  0.089  1.0
  S  S31  1  0.196  0.839  0.422  1.0
  S  S32  1  0.161  0.357  0.755  1.0
  S  S33  1  0.317  0.143  0.255  1.0
  S  S34  1  0.857  0.174  0.588  1.0
  S  S35  1  0.826  0.683  0.921  1.0
  S  S36  1  0.314  0.649  0.248  1.0
  S  S37  1  0.351  0.664  0.582  1.0
  S  S38  1  0.336  0.686  0.915  1.0
  S  S39  1  0.819  0.647  0.252  1.0
  S  S40  1  0.353  0.171  0.585  1.0
  S  S41  1  0.829  0.181  0.918  1.0
  S  S42  1  0.806  0.140  0.229  1.0
  S  S43  1  0.860  0.666  0.562  1.0
  S  S44  1  0.334  0.194  0.896  1.0
[/CIF]
.