The crystal structure described by FeCu3S8 is Pyrite-derived structured and crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms to form FeS6 octahedra that share corners with four equivalent Cu(2)S6 octahedra, corners with eight equivalent Cu(1)S6 octahedra, corners with two equivalent S(3)Cu3S tetrahedra, corners with two equivalent S(1)FeCu2S tetrahedra, and corners with two equivalent S(2)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 64-65°. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms to form CuS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, corners with four equivalent Cu(1)S6 octahedra, corners with four equivalent Cu(2)S6 octahedra,  a cornercorner with one S(1)FeCu2S tetrahedra,  a cornercorner with one S(2)FeCu2S tetrahedra, corners with two equivalent S(3)Cu3S tetrahedra, and corners with two equivalent S(4)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 64-71°. In the second Cu site, Cu(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form CuS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, corners with eight equivalent Cu(1)S6 octahedra, corners with two equivalent S(1)FeCu2S tetrahedra, corners with two equivalent S(2)FeCu2S tetrahedra, and corners with two equivalent S(4)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 64-70°. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Fe(1), one Cu(1), one Cu(2), and one S(1) atom to form distorted SFeCu2S tetrahedra that share  a cornercorner with one Fe(1)S6 octahedra,  a cornercorner with one Cu(1)S6 octahedra,  a cornercorner with one Cu(2)S6 octahedra, corners with two equivalent S(1)FeCu2S tetrahedra, corners with four equivalent S(3)Cu3S tetrahedra, corners with four equivalent S(4)FeCu2S tetrahedra, and corners with five equivalent S(2)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 69-79°. In the second S site, S(2) is bonded to one Fe(1), one Cu(1), one Cu(2), and one S(2) atom to form distorted SFeCu2S tetrahedra that share  a cornercorner with one Fe(1)S6 octahedra,  a cornercorner with one Cu(1)S6 octahedra,  a cornercorner with one Cu(2)S6 octahedra, corners with two equivalent S(2)FeCu2S tetrahedra, corners with four equivalent S(3)Cu3S tetrahedra, corners with four equivalent S(4)FeCu2S tetrahedra, and corners with five equivalent S(1)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 69-79°. In the third S site, S(3) is bonded to one Cu(2), two equivalent Cu(1), and one S(4) atom to form SCu3S tetrahedra that share  a cornercorner with one Fe(1)S6 octahedra, corners with two equivalent Cu(1)S6 octahedra, corners with three equivalent S(3)Cu3S tetrahedra, corners with four equivalent S(1)FeCu2S tetrahedra, corners with four equivalent S(2)FeCu2S tetrahedra, and corners with four equivalent S(4)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 71-78°. In the fourth S site, S(4) is bonded to one Fe(1), two equivalent Cu(1), and one S(3) atom to form distorted SFeCu2S tetrahedra that share  a cornercorner with one Cu(2)S6 octahedra, corners with two equivalent Cu(1)S6 octahedra, corners with three equivalent S(4)FeCu2S tetrahedra, corners with four equivalent S(3)Cu3S tetrahedra, corners with four equivalent S(1)FeCu2S tetrahedra, and corners with four equivalent S(2)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 71-76°. is represented by the CIF file [CIF]
data_FeCu3S8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.701
_cell_length_b   5.692
_cell_length_c   12.791
_cell_angle_alpha   64.059
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   373.245
_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
  Fe  Fe0  1  0.000  0.000  0.500  1.0
  Fe  Fe1  1  0.500  0.000  0.000  1.0
  Cu  Cu2  1  0.997  0.251  0.751  1.0
  Cu  Cu3  1  0.003  0.749  0.249  1.0
  Cu  Cu4  1  0.000  0.500  0.000  1.0
  Cu  Cu5  1  0.497  0.749  0.749  1.0
  Cu  Cu6  1  0.500  0.500  0.500  1.0
  Cu  Cu7  1  0.503  0.251  0.251  1.0
  S  S8  1  0.879  0.950  0.951  1.0
  S  S9  1  0.903  0.428  0.451  1.0
  S  S10  1  0.897  0.401  0.200  1.0
  S  S11  1  0.904  0.909  0.689  1.0
  S  S12  1  0.597  0.428  0.951  1.0
  S  S13  1  0.596  0.909  0.189  1.0
  S  S14  1  0.603  0.401  0.700  1.0
  S  S15  1  0.621  0.950  0.451  1.0
  S  S16  1  0.403  0.572  0.049  1.0
  S  S17  1  0.379  0.050  0.549  1.0
  S  S18  1  0.404  0.091  0.811  1.0
  S  S19  1  0.397  0.599  0.300  1.0
  S  S20  1  0.103  0.599  0.800  1.0
  S  S21  1  0.096  0.091  0.311  1.0
  S  S22  1  0.121  0.050  0.049  1.0
  S  S23  1  0.097  0.572  0.549  1.0
[/CIF]
.
The crystal structure described by FeCu3S8 is Pyrite-derived structured and crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(4) atoms to form FeS6 octahedra that share corners with four equivalent Cu(2)S6 octahedra, corners with eight equivalent Cu(1)S6 octahedra, corners with two equivalent S(3)Cu3S tetrahedra, corners with two equivalent S(1)FeCu2S tetrahedra, and corners with two equivalent S(2)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 64-65°. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one S(1), one S(2), two equivalent S(3), and two equivalent S(4) atoms to form CuS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, corners with four equivalent Cu(1)S6 octahedra, corners with four equivalent Cu(2)S6 octahedra,  a cornercorner with one S(1)FeCu2S tetrahedra,  a cornercorner with one S(2)FeCu2S tetrahedra, corners with two equivalent S(3)Cu3S tetrahedra, and corners with two equivalent S(4)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 64-71°. In the second Cu site, Cu(2) is bonded to two equivalent S(1), two equivalent S(2), and two equivalent S(3) atoms to form CuS6 octahedra that share corners with four equivalent Fe(1)S6 octahedra, corners with eight equivalent Cu(1)S6 octahedra, corners with two equivalent S(1)FeCu2S tetrahedra, corners with two equivalent S(2)FeCu2S tetrahedra, and corners with two equivalent S(4)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 64-70°. There are four inequivalent S sites. In the first S site, S(1) is bonded to one Fe(1), one Cu(1), one Cu(2), and one S(1) atom to form distorted SFeCu2S tetrahedra that share  a cornercorner with one Fe(1)S6 octahedra,  a cornercorner with one Cu(1)S6 octahedra,  a cornercorner with one Cu(2)S6 octahedra, corners with two equivalent S(1)FeCu2S tetrahedra, corners with four equivalent S(3)Cu3S tetrahedra, corners with four equivalent S(4)FeCu2S tetrahedra, and corners with five equivalent S(2)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 69-79°. In the second S site, S(2) is bonded to one Fe(1), one Cu(1), one Cu(2), and one S(2) atom to form distorted SFeCu2S tetrahedra that share  a cornercorner with one Fe(1)S6 octahedra,  a cornercorner with one Cu(1)S6 octahedra,  a cornercorner with one Cu(2)S6 octahedra, corners with two equivalent S(2)FeCu2S tetrahedra, corners with four equivalent S(3)Cu3S tetrahedra, corners with four equivalent S(4)FeCu2S tetrahedra, and corners with five equivalent S(1)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 69-79°. In the third S site, S(3) is bonded to one Cu(2), two equivalent Cu(1), and one S(4) atom to form SCu3S tetrahedra that share  a cornercorner with one Fe(1)S6 octahedra, corners with two equivalent Cu(1)S6 octahedra, corners with three equivalent S(3)Cu3S tetrahedra, corners with four equivalent S(1)FeCu2S tetrahedra, corners with four equivalent S(2)FeCu2S tetrahedra, and corners with four equivalent S(4)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 71-78°. In the fourth S site, S(4) is bonded to one Fe(1), two equivalent Cu(1), and one S(3) atom to form distorted SFeCu2S tetrahedra that share  a cornercorner with one Cu(2)S6 octahedra, corners with two equivalent Cu(1)S6 octahedra, corners with three equivalent S(4)FeCu2S tetrahedra, corners with four equivalent S(3)Cu3S tetrahedra, corners with four equivalent S(1)FeCu2S tetrahedra, and corners with four equivalent S(2)FeCu2S tetrahedra. The corner-sharing octahedral tilt angles range from 71-76°. is represented by the CIF file [CIF]
data_FeCu3S8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.701
_cell_length_b   5.692
_cell_length_c   12.791
_cell_angle_alpha   64.059
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   373.245
_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
  Fe  Fe0  1  0.000  0.000  0.500  1.0
  Fe  Fe1  1  0.500  0.000  0.000  1.0
  Cu  Cu2  1  0.997  0.251  0.751  1.0
  Cu  Cu3  1  0.003  0.749  0.249  1.0
  Cu  Cu4  1  0.000  0.500  0.000  1.0
  Cu  Cu5  1  0.497  0.749  0.749  1.0
  Cu  Cu6  1  0.500  0.500  0.500  1.0
  Cu  Cu7  1  0.503  0.251  0.251  1.0
  S  S8  1  0.879  0.950  0.951  1.0
  S  S9  1  0.903  0.428  0.451  1.0
  S  S10  1  0.897  0.401  0.200  1.0
  S  S11  1  0.904  0.909  0.689  1.0
  S  S12  1  0.597  0.428  0.951  1.0
  S  S13  1  0.596  0.909  0.189  1.0
  S  S14  1  0.603  0.401  0.700  1.0
  S  S15  1  0.621  0.950  0.451  1.0
  S  S16  1  0.403  0.572  0.049  1.0
  S  S17  1  0.379  0.050  0.549  1.0
  S  S18  1  0.404  0.091  0.811  1.0
  S  S19  1  0.397  0.599  0.300  1.0
  S  S20  1  0.103  0.599  0.800  1.0
  S  S21  1  0.096  0.091  0.311  1.0
  S  S22  1  0.121  0.050  0.049  1.0
  S  S23  1  0.097  0.572  0.549  1.0
[/CIF]
.