The compound described by MgFe7(Ni3O8)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form MgO6 octahedra that share corners with three equivalent Ni(4)O6 octahedra, corners with two equivalent Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-9°. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(11), one O(12), one O(5), one O(6), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(5)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(6)O6 octahedra,  an edgeedge with one Fe(7)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-18°. In the second Fe site, Fe(2) is bonded to one O(11), one O(12), one O(13), one O(14), one O(15), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Ni(5)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, edges with two equivalent Fe(7)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-18°. In the third Fe site, Fe(3) is bonded to one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with three equivalent Ni(3)O6 octahedra, corners with two equivalent Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-9°. In the fourth Fe site, Fe(4) is bonded in a 6-coordinate geometry to one O(1), one O(12), one O(16), one O(6), one O(8), and one O(9) atom. In the fifth Fe site, Fe(5) is bonded to one O(1), one O(16), one O(5), and one O(6) atom to form FeO4 tetrahedra that share  a cornercorner with one Fe(6)O6 octahedra,  a cornercorner with one Fe(7)O6 octahedra,  a cornercorner with one Ni(6)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, and corners with three equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-73°. In the sixth Fe site, Fe(6) is bonded to one O(10), one O(11), one O(14), one O(15), one O(16), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Ni(4)O6 octahedra,  a cornercorner with one Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(7)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-6°. In the seventh Fe site, Fe(7) is bonded to one O(10), one O(12), one O(13), one O(15), one O(16), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Ni(3)O6 octahedra,  a cornercorner with one Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-5°. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(8) atom to form NiO6 octahedra that share corners with three equivalent Ni(2)O6 octahedra, corners with two equivalent Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-10°. In the second Ni site, Ni(2) is bonded to one O(10), one O(13), one O(14), one O(2), one O(3), and one O(4) atom to form NiO6 octahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with three equivalent Ni(6)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(6)O6 octahedra,  an edgeedge with one Fe(7)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-10°. In the third Ni site, Ni(3) is bonded to one O(10), one O(13), one O(15), one O(2), one O(3), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(7)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(6)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-9°. In the fourth Ni site, Ni(4) is bonded to one O(10), one O(14), one O(15), one O(2), one O(4), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Fe(6)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(7)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-9°. In the fifth Ni site, Ni(5) is bonded to one O(13), one O(14), one O(15), one O(3), one O(4), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(6)O6 octahedra,  an edgeedge with one Fe(7)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-3°. In the sixth Ni site, Ni(6) is bonded to one O(10), one O(11), one O(12), one O(13), one O(14), and one O(16) atom to form NiO6 octahedra that share corners with three equivalent Ni(2)O6 octahedra,  a cornercorner with one Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with two equivalent Fe(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-6°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Mg(1), one Fe(1), one Fe(3), one Fe(4), and one Fe(5) atom. In the second O site, O(2) is bonded to one Mg(1), one Fe(3), one Ni(1), one Ni(2), one Ni(3), and one Ni(4) atom to form OMgFeNi4 octahedra that share corners with three equivalent O(10)Fe2Ni4 octahedra, corners with three equivalent O(8)MgFe2Ni trigonal pyramids,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra, edges with two equivalent O(3)FeNi4 square pyramids, edges with two equivalent O(7)MgFeNi3 square pyramids, and edges with two equivalent O(4)MgNi4 square pyramids. The corner-sharing octahedral tilt angles range from 3-7°. In the third O site, O(3) is bonded to one Fe(3), one Ni(1), one Ni(2), one Ni(3), and one Ni(5) atom to form OFeNi4 square pyramids that share corners with three equivalent O(13)Fe2Ni4 octahedra,  a cornercorner with one O(7)MgFeNi3 square pyramid,  a cornercorner with one O(4)MgNi4 square pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra, edges with two equivalent O(2)MgFeNi4 octahedra,  an edgeedge with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid, and  an edgeedge with one O(8)MgFe2Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 0-9°. In the fourth O site, O(4) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(4), and one Ni(5) atom to form OMgNi4 square pyramids that share corners with three equivalent O(14)Fe2Ni4 octahedra,  a cornercorner with one O(3)FeNi4 square pyramid,  a cornercorner with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra, edges with two equivalent O(2)MgFeNi4 octahedra,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(7)MgFeNi3 square pyramid, and  an edgeedge with one O(8)MgFe2Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-10°. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(1), one Fe(5), and one Ni(1) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(3), one Fe(4), one Fe(5), and one Ni(1) atom. In the seventh O site, O(7) is bonded to one Mg(1), one Fe(3), one Ni(3), one Ni(4), and one Ni(5) atom to form OMgFeNi3 square pyramids that share corners with three equivalent O(15)Fe3Ni3 octahedra,  a cornercorner with one O(3)FeNi4 square pyramid,  a cornercorner with one O(4)MgNi4 square pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra, edges with two equivalent O(2)MgFeNi4 octahedra,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid, and  an edgeedge with one O(8)MgFe2Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-9°. In the eighth O site, O(8) is bonded to one Mg(1), one Fe(3), one Fe(4), and one Ni(1) atom to form OMgFe2Ni trigonal pyramids that share corners with three equivalent O(2)MgFeNi4 octahedra,  a cornercorner with one O(12)Fe4Ni square pyramid,  a cornercorner with one O(16)Fe4Ni trigonal bipyramid,  a cornercorner with one O(9)Fe5 trigonal bipyramid,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(7)MgFeNi3 square pyramid, and  an edgeedge with one O(4)MgNi4 square pyramid. The corner-sharing octahedral tilt angles range from 2-6°. In the ninth O site, O(9) is bonded to one Fe(1), one Fe(2), one Fe(4), one Fe(6), and one Fe(7) atom to form OFe5 trigonal bipyramids that share corners with three equivalent O(15)Fe3Ni3 octahedra,  a cornercorner with one O(16)Fe4Ni trigonal bipyramid,  a cornercorner with one O(11)Fe3Ni trigonal pyramid,  a cornercorner with one O(8)MgFe2Ni trigonal pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra, edges with two equivalent O(12)Fe4Ni square pyramids,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 2-8°. In the tenth O site, O(10) is bonded to one Fe(6), one Fe(7), one Ni(2), one Ni(3), one Ni(4), and one Ni(6) atom to form OFe2Ni4 octahedra that share corners with three equivalent O(2)MgFeNi4 octahedra, corners with three equivalent O(16)Fe4Ni trigonal bipyramids, edges with two equivalent O(13)Fe2Ni4 octahedra, edges with two equivalent O(14)Fe2Ni4 octahedra, edges with two equivalent O(15)Fe3Ni3 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid,  an edgeedge with one O(9)Fe5 trigonal bipyramid, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-7°. In the eleventh O site, O(11) is bonded to one Fe(1), one Fe(2), one Fe(6), and one Ni(6) atom to form OFe3Ni trigonal pyramids that share corners with three equivalent O(14)Fe2Ni4 octahedra,  a cornercorner with one O(12)Fe4Ni square pyramid,  a cornercorner with one O(9)Fe5 trigonal bipyramid, corners with two equivalent O(16)Fe4Ni trigonal bipyramids,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid, and  an edgeedge with one O(9)Fe5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 4-6°. In the twelfth O site, O(12) is bonded to one Fe(1), one Fe(2), one Fe(4), one Fe(7), and one Ni(6) atom to form OFe4Ni square pyramids that share corners with three equivalent O(13)Fe2Ni4 octahedra,  a cornercorner with one O(16)Fe4Ni trigonal bipyramid,  a cornercorner with one O(11)Fe3Ni trigonal pyramid,  a cornercorner with one O(8)MgFe2Ni trigonal pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid, edges with two equivalent O(9)Fe5 trigonal bipyramids, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 1-9°. In the thirteenth O site, O(13) is bonded to one Fe(2), one Fe(7), one Ni(2), one Ni(3), one Ni(5), and one Ni(6) atom to form OFe2Ni4 octahedra that share corners with three equivalent O(12)Fe4Ni square pyramids, corners with three equivalent O(3)FeNi4 square pyramids,  an edgeedge with one O(2)MgFeNi4 octahedra, edges with two equivalent O(10)Fe2Ni4 octahedra, edges with two equivalent O(14)Fe2Ni4 octahedra, edges with two equivalent O(15)Fe3Ni3 octahedra,  an edgeedge with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid,  an edgeedge with one O(9)Fe5 trigonal bipyramid, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. In the fourteenth O site, O(14) is bonded to one Fe(2), one Fe(6), one Ni(2), one Ni(4), one Ni(5), and one Ni(6) atom to form OFe2Ni4 octahedra that share corners with three equivalent O(4)MgNi4 square pyramids, corners with three equivalent O(11)Fe3Ni trigonal pyramids,  an edgeedge with one O(2)MgFeNi4 octahedra, edges with two equivalent O(10)Fe2Ni4 octahedra, edges with two equivalent O(13)Fe2Ni4 octahedra, edges with two equivalent O(15)Fe3Ni3 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid, and  an edgeedge with one O(9)Fe5 trigonal bipyramid. In the fifteenth O site, O(15) is bonded to one Fe(2), one Fe(6), one Fe(7), one Ni(3), one Ni(4), and one Ni(5) atom to form OFe3Ni3 octahedra that share corners with three equivalent O(7)MgFeNi3 square pyramids, corners with three equivalent O(9)Fe5 trigonal bipyramids,  an edgeedge with one O(2)MgFeNi4 octahedra, edges with two equivalent O(10)Fe2Ni4 octahedra, edges with two equivalent O(13)Fe2Ni4 octahedra, edges with two equivalent O(14)Fe2Ni4 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. In the sixteenth O site, O(16) is bonded to one Fe(4), one Fe(5), one Fe(6), one Fe(7), and one Ni(6) atom to form OFe4Ni trigonal bipyramids that share corners with three equivalent O(10)Fe2Ni4 octahedra,  a cornercorner with one O(12)Fe4Ni square pyramid,  a cornercorner with one O(9)Fe5 trigonal bipyramid,  a cornercorner with one O(8)MgFe2Ni trigonal pyramid, corners with two equivalent O(11)Fe3Ni trigonal pyramids,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid, and  an edgeedge with one O(9)Fe5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 3-4°. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgFe7(Ni3O8)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.035
_cell_length_b   6.046
_cell_length_c   10.576
_cell_angle_alpha   106.482
_cell_angle_beta   72.180
_cell_angle_gamma   119.764
_symmetry_Int_Tables_number   1
_cell_volume   314.838
_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
  Mg  Mg0  1  0.066  0.462  0.342  1.0
  Fe  Fe1  1  0.326  0.712  0.082  1.0
  Fe  Fe2  1  0.024  0.935  0.835  1.0
  Fe  Fe3  1  0.580  0.964  0.331  1.0
  Fe  Fe4  1  0.206  0.152  0.076  1.0
  Fe  Fe5  1  0.657  0.418  0.159  1.0
  Fe  Fe6  1  0.540  0.943  0.828  1.0
  Fe  Fe7  1  0.024  0.438  0.840  1.0
  Ni  Ni8  1  0.067  0.966  0.339  1.0
  Ni  Ni9  1  0.308  0.691  0.574  1.0
  Ni  Ni10  1  0.795  0.692  0.571  1.0
  Ni  Ni11  1  0.308  0.207  0.575  1.0
  Ni  Ni12  1  0.801  0.202  0.583  1.0
  Ni  Ni13  1  0.537  0.439  0.829  1.0
  O  O14  1  0.445  0.600  0.217  1.0
  O  O15  1  0.192  0.834  0.459  1.0
  O  O16  1  0.684  0.850  0.464  1.0
  O  O17  1  0.161  0.325  0.473  1.0
  O  O18  1  0.977  0.607  0.214  1.0
  O  O19  1  0.446  0.085  0.217  1.0
  O  O20  1  0.683  0.320  0.465  1.0
  O  O21  1  0.939  0.100  0.235  1.0
  O  O22  1  0.175  0.822  0.940  1.0
  O  O23  1  0.430  0.579  0.702  1.0
  O  O24  1  0.654  0.805  0.932  1.0
  O  O25  1  0.164  0.302  0.938  1.0
  O  O26  1  0.923  0.579  0.712  1.0
  O  O27  1  0.412  0.064  0.711  1.0
  O  O28  1  0.913  0.057  0.709  1.0
  O  O29  1  0.626  0.298  0.961  1.0
[/CIF]
.
The compound described by MgFe7(Ni3O8)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(7), and one O(8) atom to form MgO6 octahedra that share corners with three equivalent Ni(4)O6 octahedra, corners with two equivalent Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-9°. There are seven inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(11), one O(12), one O(5), one O(6), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(5)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(6)O6 octahedra,  an edgeedge with one Fe(7)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, and  an edgeedge with one Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-18°. In the second Fe site, Fe(2) is bonded to one O(11), one O(12), one O(13), one O(14), one O(15), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Fe(1)O6 octahedra, corners with three equivalent Ni(5)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, edges with two equivalent Fe(7)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-18°. In the third Fe site, Fe(3) is bonded to one O(1), one O(2), one O(3), one O(6), one O(7), and one O(8) atom to form FeO6 octahedra that share corners with three equivalent Ni(3)O6 octahedra, corners with two equivalent Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-9°. In the fourth Fe site, Fe(4) is bonded in a 6-coordinate geometry to one O(1), one O(12), one O(16), one O(6), one O(8), and one O(9) atom. In the fifth Fe site, Fe(5) is bonded to one O(1), one O(16), one O(5), and one O(6) atom to form FeO4 tetrahedra that share  a cornercorner with one Fe(6)O6 octahedra,  a cornercorner with one Fe(7)O6 octahedra,  a cornercorner with one Ni(6)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Ni(1)O6 octahedra, and corners with three equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-73°. In the sixth Fe site, Fe(6) is bonded to one O(10), one O(11), one O(14), one O(15), one O(16), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Ni(4)O6 octahedra,  a cornercorner with one Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(7)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-6°. In the seventh Fe site, Fe(7) is bonded to one O(10), one O(12), one O(13), one O(15), one O(16), and one O(9) atom to form FeO6 octahedra that share corners with three equivalent Ni(3)O6 octahedra,  a cornercorner with one Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-5°. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), one O(6), and one O(8) atom to form NiO6 octahedra that share corners with three equivalent Ni(2)O6 octahedra, corners with two equivalent Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-10°. In the second Ni site, Ni(2) is bonded to one O(10), one O(13), one O(14), one O(2), one O(3), and one O(4) atom to form NiO6 octahedra that share corners with three equivalent Ni(1)O6 octahedra, corners with three equivalent Ni(6)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(6)O6 octahedra,  an edgeedge with one Fe(7)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-10°. In the third Ni site, Ni(3) is bonded to one O(10), one O(13), one O(15), one O(2), one O(3), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent Fe(3)O6 octahedra, corners with three equivalent Fe(7)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(6)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-9°. In the fourth Ni site, Ni(4) is bonded to one O(10), one O(14), one O(15), one O(2), one O(4), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Fe(6)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(7)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-9°. In the fifth Ni site, Ni(5) is bonded to one O(13), one O(14), one O(15), one O(3), one O(4), and one O(7) atom to form NiO6 octahedra that share corners with three equivalent Fe(2)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra,  an edgeedge with one Fe(6)O6 octahedra,  an edgeedge with one Fe(7)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-3°. In the sixth Ni site, Ni(6) is bonded to one O(10), one O(11), one O(12), one O(13), one O(14), and one O(16) atom to form NiO6 octahedra that share corners with three equivalent Ni(2)O6 octahedra,  a cornercorner with one Fe(5)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(6)O6 octahedra, and edges with two equivalent Fe(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-6°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Mg(1), one Fe(1), one Fe(3), one Fe(4), and one Fe(5) atom. In the second O site, O(2) is bonded to one Mg(1), one Fe(3), one Ni(1), one Ni(2), one Ni(3), and one Ni(4) atom to form OMgFeNi4 octahedra that share corners with three equivalent O(10)Fe2Ni4 octahedra, corners with three equivalent O(8)MgFe2Ni trigonal pyramids,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra, edges with two equivalent O(3)FeNi4 square pyramids, edges with two equivalent O(7)MgFeNi3 square pyramids, and edges with two equivalent O(4)MgNi4 square pyramids. The corner-sharing octahedral tilt angles range from 3-7°. In the third O site, O(3) is bonded to one Fe(3), one Ni(1), one Ni(2), one Ni(3), and one Ni(5) atom to form OFeNi4 square pyramids that share corners with three equivalent O(13)Fe2Ni4 octahedra,  a cornercorner with one O(7)MgFeNi3 square pyramid,  a cornercorner with one O(4)MgNi4 square pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra, edges with two equivalent O(2)MgFeNi4 octahedra,  an edgeedge with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid, and  an edgeedge with one O(8)MgFe2Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 0-9°. In the fourth O site, O(4) is bonded to one Mg(1), one Ni(1), one Ni(2), one Ni(4), and one Ni(5) atom to form OMgNi4 square pyramids that share corners with three equivalent O(14)Fe2Ni4 octahedra,  a cornercorner with one O(3)FeNi4 square pyramid,  a cornercorner with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra, edges with two equivalent O(2)MgFeNi4 octahedra,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(7)MgFeNi3 square pyramid, and  an edgeedge with one O(8)MgFe2Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-10°. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Fe(1), one Fe(5), and one Ni(1) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Fe(1), one Fe(3), one Fe(4), one Fe(5), and one Ni(1) atom. In the seventh O site, O(7) is bonded to one Mg(1), one Fe(3), one Ni(3), one Ni(4), and one Ni(5) atom to form OMgFeNi3 square pyramids that share corners with three equivalent O(15)Fe3Ni3 octahedra,  a cornercorner with one O(3)FeNi4 square pyramid,  a cornercorner with one O(4)MgNi4 square pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra, edges with two equivalent O(2)MgFeNi4 octahedra,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid, and  an edgeedge with one O(8)MgFe2Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-9°. In the eighth O site, O(8) is bonded to one Mg(1), one Fe(3), one Fe(4), and one Ni(1) atom to form OMgFe2Ni trigonal pyramids that share corners with three equivalent O(2)MgFeNi4 octahedra,  a cornercorner with one O(12)Fe4Ni square pyramid,  a cornercorner with one O(16)Fe4Ni trigonal bipyramid,  a cornercorner with one O(9)Fe5 trigonal bipyramid,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(7)MgFeNi3 square pyramid, and  an edgeedge with one O(4)MgNi4 square pyramid. The corner-sharing octahedral tilt angles range from 2-6°. In the ninth O site, O(9) is bonded to one Fe(1), one Fe(2), one Fe(4), one Fe(6), and one Fe(7) atom to form OFe5 trigonal bipyramids that share corners with three equivalent O(15)Fe3Ni3 octahedra,  a cornercorner with one O(16)Fe4Ni trigonal bipyramid,  a cornercorner with one O(11)Fe3Ni trigonal pyramid,  a cornercorner with one O(8)MgFe2Ni trigonal pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra, edges with two equivalent O(12)Fe4Ni square pyramids,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 2-8°. In the tenth O site, O(10) is bonded to one Fe(6), one Fe(7), one Ni(2), one Ni(3), one Ni(4), and one Ni(6) atom to form OFe2Ni4 octahedra that share corners with three equivalent O(2)MgFeNi4 octahedra, corners with three equivalent O(16)Fe4Ni trigonal bipyramids, edges with two equivalent O(13)Fe2Ni4 octahedra, edges with two equivalent O(14)Fe2Ni4 octahedra, edges with two equivalent O(15)Fe3Ni3 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid,  an edgeedge with one O(9)Fe5 trigonal bipyramid, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 3-7°. In the eleventh O site, O(11) is bonded to one Fe(1), one Fe(2), one Fe(6), and one Ni(6) atom to form OFe3Ni trigonal pyramids that share corners with three equivalent O(14)Fe2Ni4 octahedra,  a cornercorner with one O(12)Fe4Ni square pyramid,  a cornercorner with one O(9)Fe5 trigonal bipyramid, corners with two equivalent O(16)Fe4Ni trigonal bipyramids,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid, and  an edgeedge with one O(9)Fe5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 4-6°. In the twelfth O site, O(12) is bonded to one Fe(1), one Fe(2), one Fe(4), one Fe(7), and one Ni(6) atom to form OFe4Ni square pyramids that share corners with three equivalent O(13)Fe2Ni4 octahedra,  a cornercorner with one O(16)Fe4Ni trigonal bipyramid,  a cornercorner with one O(11)Fe3Ni trigonal pyramid,  a cornercorner with one O(8)MgFe2Ni trigonal pyramid,  an edgeedge with one O(10)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid, edges with two equivalent O(9)Fe5 trigonal bipyramids, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. The corner-sharing octahedral tilt angles range from 1-9°. In the thirteenth O site, O(13) is bonded to one Fe(2), one Fe(7), one Ni(2), one Ni(3), one Ni(5), and one Ni(6) atom to form OFe2Ni4 octahedra that share corners with three equivalent O(12)Fe4Ni square pyramids, corners with three equivalent O(3)FeNi4 square pyramids,  an edgeedge with one O(2)MgFeNi4 octahedra, edges with two equivalent O(10)Fe2Ni4 octahedra, edges with two equivalent O(14)Fe2Ni4 octahedra, edges with two equivalent O(15)Fe3Ni3 octahedra,  an edgeedge with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid,  an edgeedge with one O(9)Fe5 trigonal bipyramid, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. In the fourteenth O site, O(14) is bonded to one Fe(2), one Fe(6), one Ni(2), one Ni(4), one Ni(5), and one Ni(6) atom to form OFe2Ni4 octahedra that share corners with three equivalent O(4)MgNi4 square pyramids, corners with three equivalent O(11)Fe3Ni trigonal pyramids,  an edgeedge with one O(2)MgFeNi4 octahedra, edges with two equivalent O(10)Fe2Ni4 octahedra, edges with two equivalent O(13)Fe2Ni4 octahedra, edges with two equivalent O(15)Fe3Ni3 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(7)MgFeNi3 square pyramid,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid, and  an edgeedge with one O(9)Fe5 trigonal bipyramid. In the fifteenth O site, O(15) is bonded to one Fe(2), one Fe(6), one Fe(7), one Ni(3), one Ni(4), and one Ni(5) atom to form OFe3Ni3 octahedra that share corners with three equivalent O(7)MgFeNi3 square pyramids, corners with three equivalent O(9)Fe5 trigonal bipyramids,  an edgeedge with one O(2)MgFeNi4 octahedra, edges with two equivalent O(10)Fe2Ni4 octahedra, edges with two equivalent O(13)Fe2Ni4 octahedra, edges with two equivalent O(14)Fe2Ni4 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid,  an edgeedge with one O(3)FeNi4 square pyramid,  an edgeedge with one O(4)MgNi4 square pyramid,  an edgeedge with one O(16)Fe4Ni trigonal bipyramid, and  an edgeedge with one O(11)Fe3Ni trigonal pyramid. In the sixteenth O site, O(16) is bonded to one Fe(4), one Fe(5), one Fe(6), one Fe(7), and one Ni(6) atom to form OFe4Ni trigonal bipyramids that share corners with three equivalent O(10)Fe2Ni4 octahedra,  a cornercorner with one O(12)Fe4Ni square pyramid,  a cornercorner with one O(9)Fe5 trigonal bipyramid,  a cornercorner with one O(8)MgFe2Ni trigonal pyramid, corners with two equivalent O(11)Fe3Ni trigonal pyramids,  an edgeedge with one O(13)Fe2Ni4 octahedra,  an edgeedge with one O(14)Fe2Ni4 octahedra,  an edgeedge with one O(15)Fe3Ni3 octahedra,  an edgeedge with one O(12)Fe4Ni square pyramid, and  an edgeedge with one O(9)Fe5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 3-4°. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgFe7(Ni3O8)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.035
_cell_length_b   6.046
_cell_length_c   10.576
_cell_angle_alpha   106.482
_cell_angle_beta   72.180
_cell_angle_gamma   119.764
_symmetry_Int_Tables_number   1
_cell_volume   314.838
_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
  Mg  Mg0  1  0.066  0.462  0.342  1.0
  Fe  Fe1  1  0.326  0.712  0.082  1.0
  Fe  Fe2  1  0.024  0.935  0.835  1.0
  Fe  Fe3  1  0.580  0.964  0.331  1.0
  Fe  Fe4  1  0.206  0.152  0.076  1.0
  Fe  Fe5  1  0.657  0.418  0.159  1.0
  Fe  Fe6  1  0.540  0.943  0.828  1.0
  Fe  Fe7  1  0.024  0.438  0.840  1.0
  Ni  Ni8  1  0.067  0.966  0.339  1.0
  Ni  Ni9  1  0.308  0.691  0.574  1.0
  Ni  Ni10  1  0.795  0.692  0.571  1.0
  Ni  Ni11  1  0.308  0.207  0.575  1.0
  Ni  Ni12  1  0.801  0.202  0.583  1.0
  Ni  Ni13  1  0.537  0.439  0.829  1.0
  O  O14  1  0.445  0.600  0.217  1.0
  O  O15  1  0.192  0.834  0.459  1.0
  O  O16  1  0.684  0.850  0.464  1.0
  O  O17  1  0.161  0.325  0.473  1.0
  O  O18  1  0.977  0.607  0.214  1.0
  O  O19  1  0.446  0.085  0.217  1.0
  O  O20  1  0.683  0.320  0.465  1.0
  O  O21  1  0.939  0.100  0.235  1.0
  O  O22  1  0.175  0.822  0.940  1.0
  O  O23  1  0.430  0.579  0.702  1.0
  O  O24  1  0.654  0.805  0.932  1.0
  O  O25  1  0.164  0.302  0.938  1.0
  O  O26  1  0.923  0.579  0.712  1.0
  O  O27  1  0.412  0.064  0.711  1.0
  O  O28  1  0.913  0.057  0.709  1.0
  O  O29  1  0.626  0.298  0.961  1.0
[/CIF]
.