The crystal structure described by Fe7(SiO3)8 crystallizes in the monoclinic C2/m space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent O(5) and two equivalent O(7) atoms. In the second Fe site, Fe(2) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(3) and four equivalent O(6) atoms to form FeO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(4)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(4)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra,  a cornercorner with one Fe(4)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-60°. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-60°. There are seven inequivalent O sites. In the first O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Fe(3) and two equivalent Fe(4) atoms. In the third O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1), one Fe(2), and one Si(2) atom. In the fifth O site, O(6) is bonded to one Fe(2), one Fe(3), one Fe(4), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OFe3Si trigonal pyramids. In the sixth O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(4), and one Si(2) atom. In the seventh O site, O(1) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe7(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.436
_cell_length_b   10.436
_cell_length_c   5.369
_cell_angle_alpha   84.119
_cell_angle_beta   84.119
_cell_angle_gamma   124.371
_symmetry_Int_Tables_number   1
_cell_volume   470.921
_cell_formula_units_Z   1
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  0.742  0.258  0.500  1.0
  Fe  Fe1  1  0.258  0.742  0.500  1.0
  Fe  Fe2  1  0.821  0.179  0.000  1.0
  Fe  Fe3  1  0.179  0.821  0.000  1.0
  Fe  Fe4  1  0.000  0.000  0.000  1.0
  Fe  Fe5  1  0.920  0.080  0.500  1.0
  Fe  Fe6  1  0.080  0.920  0.500  1.0
  Si  Si7  1  0.627  0.793  0.273  1.0
  Si  Si8  1  0.373  0.207  0.727  1.0
  Si  Si9  1  0.207  0.373  0.727  1.0
  Si  Si10  1  0.793  0.627  0.273  1.0
  Si  Si11  1  0.464  0.130  0.222  1.0
  Si  Si12  1  0.536  0.870  0.778  1.0
  Si  Si13  1  0.870  0.536  0.778  1.0
  Si  Si14  1  0.130  0.464  0.222  1.0
  O  O15  1  0.469  0.232  0.444  1.0
  O  O16  1  0.531  0.768  0.556  1.0
  O  O17  1  0.768  0.531  0.556  1.0
  O  O18  1  0.232  0.469  0.444  1.0
  O  O19  1  0.654  0.654  0.273  1.0
  O  O20  1  0.346  0.346  0.727  1.0
  O  O21  1  0.901  0.901  0.722  1.0
  O  O22  1  0.099  0.099  0.278  1.0
  O  O23  1  0.518  0.782  0.065  1.0
  O  O24  1  0.482  0.218  0.935  1.0
  O  O25  1  0.218  0.482  0.935  1.0
  O  O26  1  0.782  0.518  0.065  1.0
  O  O27  1  0.624  0.138  0.234  1.0
  O  O28  1  0.376  0.862  0.766  1.0
  O  O29  1  0.862  0.376  0.766  1.0
  O  O30  1  0.138  0.624  0.234  1.0
  O  O31  1  0.798  0.969  0.206  1.0
  O  O32  1  0.202  0.031  0.794  1.0
  O  O33  1  0.031  0.202  0.794  1.0
  O  O34  1  0.969  0.798  0.206  1.0
  O  O35  1  0.295  0.953  0.291  1.0
  O  O36  1  0.705  0.047  0.709  1.0
  O  O37  1  0.047  0.705  0.709  1.0
  O  O38  1  0.953  0.295  0.291  1.0
[/CIF]
.
The crystal structure described by Fe7(SiO3)8 crystallizes in the monoclinic C2/m space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent O(5) and two equivalent O(7) atoms. In the second Fe site, Fe(2) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(3) and four equivalent O(6) atoms to form FeO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(4)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(4)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra,  a cornercorner with one Fe(4)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 59-60°. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-60°. There are seven inequivalent O sites. In the first O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Fe(3) and two equivalent Fe(4) atoms. In the third O site, O(4) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Fe(1), one Fe(2), and one Si(2) atom. In the fifth O site, O(6) is bonded to one Fe(2), one Fe(3), one Fe(4), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OFe3Si trigonal pyramids. In the sixth O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(4), and one Si(2) atom. In the seventh O site, O(1) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe7(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.436
_cell_length_b   10.436
_cell_length_c   5.369
_cell_angle_alpha   84.119
_cell_angle_beta   84.119
_cell_angle_gamma   124.371
_symmetry_Int_Tables_number   1
_cell_volume   470.921
_cell_formula_units_Z   1
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  0.742  0.258  0.500  1.0
  Fe  Fe1  1  0.258  0.742  0.500  1.0
  Fe  Fe2  1  0.821  0.179  0.000  1.0
  Fe  Fe3  1  0.179  0.821  0.000  1.0
  Fe  Fe4  1  0.000  0.000  0.000  1.0
  Fe  Fe5  1  0.920  0.080  0.500  1.0
  Fe  Fe6  1  0.080  0.920  0.500  1.0
  Si  Si7  1  0.627  0.793  0.273  1.0
  Si  Si8  1  0.373  0.207  0.727  1.0
  Si  Si9  1  0.207  0.373  0.727  1.0
  Si  Si10  1  0.793  0.627  0.273  1.0
  Si  Si11  1  0.464  0.130  0.222  1.0
  Si  Si12  1  0.536  0.870  0.778  1.0
  Si  Si13  1  0.870  0.536  0.778  1.0
  Si  Si14  1  0.130  0.464  0.222  1.0
  O  O15  1  0.469  0.232  0.444  1.0
  O  O16  1  0.531  0.768  0.556  1.0
  O  O17  1  0.768  0.531  0.556  1.0
  O  O18  1  0.232  0.469  0.444  1.0
  O  O19  1  0.654  0.654  0.273  1.0
  O  O20  1  0.346  0.346  0.727  1.0
  O  O21  1  0.901  0.901  0.722  1.0
  O  O22  1  0.099  0.099  0.278  1.0
  O  O23  1  0.518  0.782  0.065  1.0
  O  O24  1  0.482  0.218  0.935  1.0
  O  O25  1  0.218  0.482  0.935  1.0
  O  O26  1  0.782  0.518  0.065  1.0
  O  O27  1  0.624  0.138  0.234  1.0
  O  O28  1  0.376  0.862  0.766  1.0
  O  O29  1  0.862  0.376  0.766  1.0
  O  O30  1  0.138  0.624  0.234  1.0
  O  O31  1  0.798  0.969  0.206  1.0
  O  O32  1  0.202  0.031  0.794  1.0
  O  O33  1  0.031  0.202  0.794  1.0
  O  O34  1  0.969  0.798  0.206  1.0
  O  O35  1  0.295  0.953  0.291  1.0
  O  O36  1  0.705  0.047  0.709  1.0
  O  O37  1  0.047  0.705  0.709  1.0
  O  O38  1  0.953  0.295  0.291  1.0
[/CIF]
.