MgMn4(FeO4)2 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with six equivalent Fe(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-11°. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the second Mn site, Mn(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. In the third Mn site, Mn(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-11°. In the second Fe site, Fe(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, and edges with two equivalent Fe(1)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Mn(1), one Mn(2), one Mn(3), and one Fe(1) atom to form distorted OMgMn3Fe square pyramids that share  a cornercorner with one O(3)MgMn2Fe2 square pyramid,  a cornercorner with one O(4)MgMn2Fe2 square pyramid, corners with four equivalent O(1)MgMn3Fe square pyramids, corners with three equivalent O(2)Mn3Fe tetrahedra, edges with three equivalent O(3)MgMn2Fe2 square pyramids, edges with three equivalent O(4)MgMn2Fe2 square pyramids, and  an edgeedge with one O(2)Mn3Fe tetrahedra. In the second O site, O(2) is bonded to one Mn(1), one Mn(2), one Mn(3), and one Fe(2) atom to form OMn3Fe tetrahedra that share corners with three equivalent O(3)MgMn2Fe2 square pyramids, corners with three equivalent O(4)MgMn2Fe2 square pyramids, corners with three equivalent O(1)MgMn3Fe square pyramids, corners with three equivalent O(2)Mn3Fe tetrahedra,  an edgeedge with one O(3)MgMn2Fe2 square pyramid,  an edgeedge with one O(4)MgMn2Fe2 square pyramid, and  an edgeedge with one O(1)MgMn3Fe square pyramid. In the third O site, O(3) is bonded to one Mg(1), one Mn(1), one Mn(2), one Fe(1), and one Fe(2) atom to form distorted OMgMn2Fe2 square pyramids that share  a cornercorner with one O(4)MgMn2Fe2 square pyramid,  a cornercorner with one O(1)MgMn3Fe square pyramid, corners with four equivalent O(3)MgMn2Fe2 square pyramids, corners with three equivalent O(2)Mn3Fe tetrahedra, edges with three equivalent O(4)MgMn2Fe2 square pyramids, edges with three equivalent O(1)MgMn3Fe square pyramids, and  an edgeedge with one O(2)Mn3Fe tetrahedra. In the fourth O site, O(4) is bonded to one Mg(1), one Mn(1), one Mn(3), one Fe(1), and one Fe(2) atom to form OMgMn2Fe2 square pyramids that share  a cornercorner with one O(3)MgMn2Fe2 square pyramid,  a cornercorner with one O(1)MgMn3Fe square pyramid, corners with four equivalent O(4)MgMn2Fe2 square pyramids, corners with three equivalent O(2)Mn3Fe tetrahedra, edges with three equivalent O(3)MgMn2Fe2 square pyramids, edges with three equivalent O(1)MgMn3Fe square pyramids, and  an edgeedge with one O(2)Mn3Fe tetrahedra.
MgMn4(FeO4)2 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with six equivalent Fe(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-11°. Both Mg(1)-O(1) bond lengths are 2.19 Å. Both Mg(1)-O(3) bond lengths are 2.10 Å. Both Mg(1)-O(4) bond lengths are 2.18 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a rectangular see-saw-like geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Mn(1)-O(1) bond length is 2.13 Å. The Mn(1)-O(2) bond length is 1.98 Å. The Mn(1)-O(3) bond length is 2.16 Å. The Mn(1)-O(4) bond length is 2.21 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. Both Mn(2)-O(1) bond lengths are 2.02 Å. Both Mn(2)-O(2) bond lengths are 1.93 Å. Both Mn(2)-O(3) bond lengths are 2.34 Å. In the third Mn site, Mn(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form MnO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. Both Mn(3)-O(1) bond lengths are 2.20 Å. Both Mn(3)-O(2) bond lengths are 2.08 Å. Both Mn(3)-O(4) bond lengths are 2.29 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-11°. Both Fe(1)-O(1) bond lengths are 2.41 Å. Both Fe(1)-O(3) bond lengths are 2.40 Å. Both Fe(1)-O(4) bond lengths are 2.12 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(2)O6 octahedra, edges with two equivalent Mn(3)O6 octahedra, and edges with two equivalent Fe(1)O6 octahedra. Both Fe(2)-O(2) bond lengths are 1.99 Å. Both Fe(2)-O(3) bond lengths are 2.08 Å. Both Fe(2)-O(4) bond lengths are 2.13 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Mn(1), one Mn(2), one Mn(3), and one Fe(1) atom to form distorted OMgMn3Fe square pyramids that share  a cornercorner with one O(3)MgMn2Fe2 square pyramid,  a cornercorner with one O(4)MgMn2Fe2 square pyramid, corners with four equivalent O(1)MgMn3Fe square pyramids, corners with three equivalent O(2)Mn3Fe tetrahedra, edges with three equivalent O(3)MgMn2Fe2 square pyramids, edges with three equivalent O(4)MgMn2Fe2 square pyramids, and  an edgeedge with one O(2)Mn3Fe tetrahedra. In the second O site, O(2) is bonded to one Mn(1), one Mn(2), one Mn(3), and one Fe(2) atom to form OMn3Fe tetrahedra that share corners with three equivalent O(3)MgMn2Fe2 square pyramids, corners with three equivalent O(4)MgMn2Fe2 square pyramids, corners with three equivalent O(1)MgMn3Fe square pyramids, corners with three equivalent O(2)Mn3Fe tetrahedra,  an edgeedge with one O(3)MgMn2Fe2 square pyramid,  an edgeedge with one O(4)MgMn2Fe2 square pyramid, and  an edgeedge with one O(1)MgMn3Fe square pyramid. In the third O site, O(3) is bonded to one Mg(1), one Mn(1), one Mn(2), one Fe(1), and one Fe(2) atom to form distorted OMgMn2Fe2 square pyramids that share  a cornercorner with one O(4)MgMn2Fe2 square pyramid,  a cornercorner with one O(1)MgMn3Fe square pyramid, corners with four equivalent O(3)MgMn2Fe2 square pyramids, corners with three equivalent O(2)Mn3Fe tetrahedra, edges with three equivalent O(4)MgMn2Fe2 square pyramids, edges with three equivalent O(1)MgMn3Fe square pyramids, and  an edgeedge with one O(2)Mn3Fe tetrahedra. In the fourth O site, O(4) is bonded to one Mg(1), one Mn(1), one Mn(3), one Fe(1), and one Fe(2) atom to form OMgMn2Fe2 square pyramids that share  a cornercorner with one O(3)MgMn2Fe2 square pyramid,  a cornercorner with one O(1)MgMn3Fe square pyramid, corners with four equivalent O(4)MgMn2Fe2 square pyramids, corners with three equivalent O(2)Mn3Fe tetrahedra, edges with three equivalent O(3)MgMn2Fe2 square pyramids, edges with three equivalent O(1)MgMn3Fe square pyramids, and  an edgeedge with one O(2)Mn3Fe tetrahedra.