MgMn2O4 crystallizes in the orthorhombic Cmcm space group. Mg(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms. Mn(1) is bonded to one O(2), two equivalent O(3), and three equivalent O(1) atoms to form a mixture of corner and edge-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles range from 0-56°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1) and three equivalent Mn(1) atoms to form distorted OMg2Mn3 trigonal bipyramids that share corners with four equivalent O(3)Mg2Mn4 octahedra, corners with five equivalent O(2)Mg2Mn2 tetrahedra, corners with two equivalent O(1)Mg2Mn3 trigonal bipyramids, edges with three equivalent O(3)Mg2Mn4 octahedra,  an edgeedge with one O(2)Mg2Mn2 tetrahedra, and edges with five equivalent O(1)Mg2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 8-44°. In the second O site, O(2) is bonded to two equivalent Mg(1) and two equivalent Mn(1) atoms to form OMg2Mn2 tetrahedra that share corners with two equivalent O(2)Mg2Mn2 tetrahedra, corners with ten equivalent O(1)Mg2Mn3 trigonal bipyramids, edges with four equivalent O(3)Mg2Mn4 octahedra, and edges with two equivalent O(1)Mg2Mn3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Mg(1) and four equivalent Mn(1) atoms to form distorted OMg2Mn4 octahedra that share corners with two equivalent O(3)Mg2Mn4 octahedra, corners with eight equivalent O(1)Mg2Mn3 trigonal bipyramids, edges with two equivalent O(3)Mg2Mn4 octahedra, edges with four equivalent O(2)Mg2Mn2 tetrahedra, and edges with six equivalent O(1)Mg2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 47°.
MgMn2O4 crystallizes in the orthorhombic Cmcm space group. Mg(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms. Both Mg(1)-O(2) bond lengths are 2.10 Å. Both Mg(1)-O(3) bond lengths are 2.61 Å. All Mg(1)-O(1) bond lengths are 2.28 Å. Mn(1) is bonded to one O(2), two equivalent O(3), and three equivalent O(1) atoms to form a mixture of corner and edge-sharing MnO6 octahedra. The corner-sharing octahedral tilt angles range from 0-56°. The Mn(1)-O(2) bond length is 1.94 Å. Both Mn(1)-O(3) bond lengths are 2.11 Å. There is one shorter (1.96 Å) and two longer (2.13 Å) Mn(1)-O(1) bond lengths. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1) and three equivalent Mn(1) atoms to form distorted OMg2Mn3 trigonal bipyramids that share corners with four equivalent O(3)Mg2Mn4 octahedra, corners with five equivalent O(2)Mg2Mn2 tetrahedra, corners with two equivalent O(1)Mg2Mn3 trigonal bipyramids, edges with three equivalent O(3)Mg2Mn4 octahedra,  an edgeedge with one O(2)Mg2Mn2 tetrahedra, and edges with five equivalent O(1)Mg2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 8-44°. In the second O site, O(2) is bonded to two equivalent Mg(1) and two equivalent Mn(1) atoms to form OMg2Mn2 tetrahedra that share corners with two equivalent O(2)Mg2Mn2 tetrahedra, corners with ten equivalent O(1)Mg2Mn3 trigonal bipyramids, edges with four equivalent O(3)Mg2Mn4 octahedra, and edges with two equivalent O(1)Mg2Mn3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Mg(1) and four equivalent Mn(1) atoms to form distorted OMg2Mn4 octahedra that share corners with two equivalent O(3)Mg2Mn4 octahedra, corners with eight equivalent O(1)Mg2Mn3 trigonal bipyramids, edges with two equivalent O(3)Mg2Mn4 octahedra, edges with four equivalent O(2)Mg2Mn2 tetrahedra, and edges with six equivalent O(1)Mg2Mn3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 47°.