The compound described by Fe7(SiO6)2 is Spinel-like structured and crystallizes in the monoclinic C2/c space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(5)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Fe(5)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(5)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and edges with three equivalent Fe(4)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(2), one O(4), one O(5), one O(6), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Fe(5)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, and edges with three equivalent Fe(3)O6 octahedra. In the fifth Fe site, Fe(5) is bonded to two equivalent O(5) and two equivalent O(6) atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedral tilt angles range from 53-59°. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent Fe(3)O6 octahedra, and corners with four equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-53°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(4), and one Si(1) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Fe(3), two equivalent Fe(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Fe(4), two equivalent Fe(3), and one Si(1) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Fe(2), one Fe(3), one Fe(4), and one Fe(5) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(3), one Fe(4), and one Fe(5) atom. is represented by the CIF file [CIF]
data_Fe7(SiO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.940
_cell_length_b   5.940
_cell_length_c   13.399
_cell_angle_alpha   77.342
_cell_angle_beta   77.342
_cell_angle_gamma   89.976
_symmetry_Int_Tables_number   1
_cell_volume   449.549
_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  0.500  0.000  1.0
  Fe  Fe1  1  0.500  0.500  0.000  1.0
  Fe  Fe2  1  0.166  0.165  0.164  1.0
  Fe  Fe3  1  0.167  0.673  0.163  1.0
  Fe  Fe4  1  0.626  0.374  0.250  1.0
  Fe  Fe5  1  0.835  0.834  0.336  1.0
  Fe  Fe6  1  0.327  0.833  0.337  1.0
  Fe  Fe7  1  0.500  0.500  0.500  1.0
  Fe  Fe8  1  0.500  0.000  0.500  1.0
  Fe  Fe9  1  0.673  0.167  0.663  1.0
  Fe  Fe10  1  0.165  0.166  0.664  1.0
  Fe  Fe11  1  0.374  0.626  0.750  1.0
  Fe  Fe12  1  0.834  0.835  0.836  1.0
  Fe  Fe13  1  0.833  0.327  0.837  1.0
  Si  Si14  1  0.297  0.043  0.914  1.0
  Si  Si15  1  0.703  0.957  0.086  1.0
  Si  Si16  1  0.043  0.297  0.414  1.0
  Si  Si17  1  0.957  0.703  0.586  1.0
  O  O18  1  0.263  0.236  0.990  1.0
  O  O19  1  0.263  0.774  0.990  1.0
  O  O20  1  0.737  0.764  0.010  1.0
  O  O21  1  0.737  0.226  0.010  1.0
  O  O22  1  0.435  0.919  0.163  1.0
  O  O23  1  0.898  0.920  0.161  1.0
  O  O24  1  0.417  0.422  0.156  1.0
  O  O25  1  0.927  0.420  0.160  1.0
  O  O26  1  0.580  0.073  0.340  1.0
  O  O27  1  0.578  0.583  0.344  1.0
  O  O28  1  0.080  0.102  0.339  1.0
  O  O29  1  0.081  0.565  0.337  1.0
  O  O30  1  0.236  0.263  0.490  1.0
  O  O31  1  0.774  0.263  0.490  1.0
  O  O32  1  0.226  0.737  0.510  1.0
  O  O33  1  0.764  0.737  0.510  1.0
  O  O34  1  0.920  0.898  0.661  1.0
  O  O35  1  0.919  0.435  0.663  1.0
  O  O36  1  0.420  0.927  0.660  1.0
  O  O37  1  0.422  0.417  0.656  1.0
  O  O38  1  0.583  0.578  0.844  1.0
  O  O39  1  0.073  0.580  0.840  1.0
  O  O40  1  0.565  0.081  0.837  1.0
  O  O41  1  0.102  0.080  0.839  1.0
[/CIF]
.
The compound described by Fe7(SiO6)2 is Spinel-like structured and crystallizes in the monoclinic C2/c space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(5)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Fe(5)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(5)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and edges with three equivalent Fe(4)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(2), one O(4), one O(5), one O(6), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Fe(5)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, and edges with three equivalent Fe(3)O6 octahedra. In the fifth Fe site, Fe(5) is bonded to two equivalent O(5) and two equivalent O(6) atoms to form corner-sharing FeO4 tetrahedra. The corner-sharing octahedral tilt angles range from 53-59°. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent Fe(3)O6 octahedra, and corners with four equivalent Fe(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-53°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(4), and one Si(1) atom. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to one Fe(3), two equivalent Fe(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Fe(4), two equivalent Fe(3), and one Si(1) atom. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Fe(2), one Fe(3), one Fe(4), and one Fe(5) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Fe(1), one Fe(3), one Fe(4), and one Fe(5) atom. is represented by the CIF file [CIF]
data_Fe7(SiO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.940
_cell_length_b   5.940
_cell_length_c   13.399
_cell_angle_alpha   77.342
_cell_angle_beta   77.342
_cell_angle_gamma   89.976
_symmetry_Int_Tables_number   1
_cell_volume   449.549
_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  0.500  0.000  1.0
  Fe  Fe1  1  0.500  0.500  0.000  1.0
  Fe  Fe2  1  0.166  0.165  0.164  1.0
  Fe  Fe3  1  0.167  0.673  0.163  1.0
  Fe  Fe4  1  0.626  0.374  0.250  1.0
  Fe  Fe5  1  0.835  0.834  0.336  1.0
  Fe  Fe6  1  0.327  0.833  0.337  1.0
  Fe  Fe7  1  0.500  0.500  0.500  1.0
  Fe  Fe8  1  0.500  0.000  0.500  1.0
  Fe  Fe9  1  0.673  0.167  0.663  1.0
  Fe  Fe10  1  0.165  0.166  0.664  1.0
  Fe  Fe11  1  0.374  0.626  0.750  1.0
  Fe  Fe12  1  0.834  0.835  0.836  1.0
  Fe  Fe13  1  0.833  0.327  0.837  1.0
  Si  Si14  1  0.297  0.043  0.914  1.0
  Si  Si15  1  0.703  0.957  0.086  1.0
  Si  Si16  1  0.043  0.297  0.414  1.0
  Si  Si17  1  0.957  0.703  0.586  1.0
  O  O18  1  0.263  0.236  0.990  1.0
  O  O19  1  0.263  0.774  0.990  1.0
  O  O20  1  0.737  0.764  0.010  1.0
  O  O21  1  0.737  0.226  0.010  1.0
  O  O22  1  0.435  0.919  0.163  1.0
  O  O23  1  0.898  0.920  0.161  1.0
  O  O24  1  0.417  0.422  0.156  1.0
  O  O25  1  0.927  0.420  0.160  1.0
  O  O26  1  0.580  0.073  0.340  1.0
  O  O27  1  0.578  0.583  0.344  1.0
  O  O28  1  0.080  0.102  0.339  1.0
  O  O29  1  0.081  0.565  0.337  1.0
  O  O30  1  0.236  0.263  0.490  1.0
  O  O31  1  0.774  0.263  0.490  1.0
  O  O32  1  0.226  0.737  0.510  1.0
  O  O33  1  0.764  0.737  0.510  1.0
  O  O34  1  0.920  0.898  0.661  1.0
  O  O35  1  0.919  0.435  0.663  1.0
  O  O36  1  0.420  0.927  0.660  1.0
  O  O37  1  0.422  0.417  0.656  1.0
  O  O38  1  0.583  0.578  0.844  1.0
  O  O39  1  0.073  0.580  0.840  1.0
  O  O40  1  0.565  0.081  0.837  1.0
  O  O41  1  0.102  0.080  0.839  1.0
[/CIF]
.