The structure described by MgMn4O8 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(3), one O(8), two equivalent O(1), and two equivalent O(7) atoms to form distorted MgO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with three equivalent Mn(2)O6 octahedra,  an edgeedge with one Mn(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and  a faceface with one Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-40°. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(7), two equivalent O(3), and two equivalent O(8) atoms to form distorted MnO6 octahedra that share corners with four equivalent Mn(3)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-54°. In the second Mn site, Mn(2) is bonded to one O(2), one O(8), two equivalent O(4), and two equivalent O(7) atoms to form distorted MnO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with four equivalent Mn(4)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, and edges with two equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-54°. In the third Mn site, Mn(3) is bonded to one O(3), one O(6), two equivalent O(1), and two equivalent O(5) atoms to form MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Mn(4)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-54°. In the fourth Mn site, Mn(4) is bonded to one O(4), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form a mixture of corner and edge-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles range from 51-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Mn(1), and two equivalent Mn(3) atoms to form distorted OMg2Mn3 trigonal bipyramids that share corners with three equivalent O(7)Mg2Mn3 square pyramids, corners with two equivalent O(3)MgMn3 trigonal pyramids,  an edgeedge with one O(7)Mg2Mn3 square pyramid, edges with two equivalent O(8)MgMn3 tetrahedra, edges with two equivalent O(1)Mg2Mn3 trigonal bipyramids, and edges with two equivalent O(3)MgMn3 trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mn(2) and two equivalent Mn(4) atoms. In the third O site, O(3) is bonded to one Mg(1), one Mn(3), and two equivalent Mn(1) atoms to form OMgMn3 trigonal pyramids that share corners with three equivalent O(8)MgMn3 tetrahedra, corners with two equivalent O(1)Mg2Mn3 trigonal bipyramids, corners with two equivalent O(3)MgMn3 trigonal pyramids, edges with two equivalent O(7)Mg2Mn3 square pyramids,  an edgeedge with one O(8)MgMn3 tetrahedra, and edges with two equivalent O(1)Mg2Mn3 trigonal bipyramids. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mn(4) and two equivalent Mn(2) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Mn(4) and two equivalent Mn(3) atoms. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Mn(3) and two equivalent Mn(4) atoms. In the seventh O site, O(7) is bonded to two equivalent Mg(1), one Mn(1), and two equivalent Mn(2) atoms to form OMg2Mn3 square pyramids that share corners with two equivalent O(8)MgMn3 tetrahedra, corners with three equivalent O(1)Mg2Mn3 trigonal bipyramids, edges with two equivalent O(7)Mg2Mn3 square pyramids, edges with two equivalent O(8)MgMn3 tetrahedra,  an edgeedge with one O(1)Mg2Mn3 trigonal bipyramid, and edges with two equivalent O(3)MgMn3 trigonal pyramids. In the eighth O site, O(8) is bonded to one Mg(1), one Mn(2), and two equivalent Mn(1) atoms to form distorted OMgMn3 tetrahedra that share corners with two equivalent O(7)Mg2Mn3 square pyramids, corners with two equivalent O(8)MgMn3 tetrahedra, corners with three equivalent O(3)MgMn3 trigonal pyramids, edges with two equivalent O(7)Mg2Mn3 square pyramids, edges with two equivalent O(1)Mg2Mn3 trigonal bipyramids, and  an edgeedge with one O(3)MgMn3 trigonal pyramid. is represented by the CIF file [CIF]
data_MgMn4O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.923
_cell_length_b   5.312
_cell_length_c   9.294
_cell_angle_alpha   91.855
_cell_angle_beta   90.015
_cell_angle_gamma   90.029
_symmetry_Int_Tables_number   1
_cell_volume   144.260
_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  0.773  0.928  0.578  1.0
  Mn  Mn1  1  0.272  0.435  0.655  1.0
  Mn  Mn2  1  0.773  0.561  0.347  1.0
  Mn  Mn3  1  0.772  0.923  0.879  1.0
  Mn  Mn4  1  0.273  0.076  0.141  1.0
  O  O5  1  0.272  0.059  0.755  1.0
  O  O6  1  0.773  0.931  0.242  1.0
  O  O7  1  0.772  0.638  0.737  1.0
  O  O8  1  0.273  0.396  0.250  1.0
  O  O9  1  0.272  0.803  0.992  1.0
  O  O10  1  0.773  0.195  0.017  1.0
  O  O11  1  0.273  0.725  0.473  1.0
  O  O12  1  0.772  0.289  0.541  1.0
[/CIF]
.
The structure described by MgMn4O8 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(3), one O(8), two equivalent O(1), and two equivalent O(7) atoms to form distorted MgO6 octahedra that share corners with two equivalent Mn(3)O6 octahedra, corners with three equivalent Mn(2)O6 octahedra,  an edgeedge with one Mn(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Mn(1)O6 octahedra, and  a faceface with one Mn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-40°. There are four inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(7), two equivalent O(3), and two equivalent O(8) atoms to form distorted MnO6 octahedra that share corners with four equivalent Mn(3)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, and edges with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-54°. In the second Mn site, Mn(2) is bonded to one O(2), one O(8), two equivalent O(4), and two equivalent O(7) atoms to form distorted MnO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with four equivalent Mn(4)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, and edges with two equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-54°. In the third Mn site, Mn(3) is bonded to one O(3), one O(6), two equivalent O(1), and two equivalent O(5) atoms to form MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with four equivalent Mn(1)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Mn(4)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-54°. In the fourth Mn site, Mn(4) is bonded to one O(4), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form a mixture of corner and edge-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles range from 51-54°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Mn(1), and two equivalent Mn(3) atoms to form distorted OMg2Mn3 trigonal bipyramids that share corners with three equivalent O(7)Mg2Mn3 square pyramids, corners with two equivalent O(3)MgMn3 trigonal pyramids,  an edgeedge with one O(7)Mg2Mn3 square pyramid, edges with two equivalent O(8)MgMn3 tetrahedra, edges with two equivalent O(1)Mg2Mn3 trigonal bipyramids, and edges with two equivalent O(3)MgMn3 trigonal pyramids. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mn(2) and two equivalent Mn(4) atoms. In the third O site, O(3) is bonded to one Mg(1), one Mn(3), and two equivalent Mn(1) atoms to form OMgMn3 trigonal pyramids that share corners with three equivalent O(8)MgMn3 tetrahedra, corners with two equivalent O(1)Mg2Mn3 trigonal bipyramids, corners with two equivalent O(3)MgMn3 trigonal pyramids, edges with two equivalent O(7)Mg2Mn3 square pyramids,  an edgeedge with one O(8)MgMn3 tetrahedra, and edges with two equivalent O(1)Mg2Mn3 trigonal bipyramids. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mn(4) and two equivalent Mn(2) atoms. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Mn(4) and two equivalent Mn(3) atoms. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Mn(3) and two equivalent Mn(4) atoms. In the seventh O site, O(7) is bonded to two equivalent Mg(1), one Mn(1), and two equivalent Mn(2) atoms to form OMg2Mn3 square pyramids that share corners with two equivalent O(8)MgMn3 tetrahedra, corners with three equivalent O(1)Mg2Mn3 trigonal bipyramids, edges with two equivalent O(7)Mg2Mn3 square pyramids, edges with two equivalent O(8)MgMn3 tetrahedra,  an edgeedge with one O(1)Mg2Mn3 trigonal bipyramid, and edges with two equivalent O(3)MgMn3 trigonal pyramids. In the eighth O site, O(8) is bonded to one Mg(1), one Mn(2), and two equivalent Mn(1) atoms to form distorted OMgMn3 tetrahedra that share corners with two equivalent O(7)Mg2Mn3 square pyramids, corners with two equivalent O(8)MgMn3 tetrahedra, corners with three equivalent O(3)MgMn3 trigonal pyramids, edges with two equivalent O(7)Mg2Mn3 square pyramids, edges with two equivalent O(1)Mg2Mn3 trigonal bipyramids, and  an edgeedge with one O(3)MgMn3 trigonal pyramid. is represented by the CIF file [CIF]
data_MgMn4O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.923
_cell_length_b   5.312
_cell_length_c   9.294
_cell_angle_alpha   91.855
_cell_angle_beta   90.015
_cell_angle_gamma   90.029
_symmetry_Int_Tables_number   1
_cell_volume   144.260
_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  0.773  0.928  0.578  1.0
  Mn  Mn1  1  0.272  0.435  0.655  1.0
  Mn  Mn2  1  0.773  0.561  0.347  1.0
  Mn  Mn3  1  0.772  0.923  0.879  1.0
  Mn  Mn4  1  0.273  0.076  0.141  1.0
  O  O5  1  0.272  0.059  0.755  1.0
  O  O6  1  0.773  0.931  0.242  1.0
  O  O7  1  0.772  0.638  0.737  1.0
  O  O8  1  0.273  0.396  0.250  1.0
  O  O9  1  0.272  0.803  0.992  1.0
  O  O10  1  0.773  0.195  0.017  1.0
  O  O11  1  0.273  0.725  0.473  1.0
  O  O12  1  0.772  0.289  0.541  1.0
[/CIF]
.