MgFe2O4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO5 trigonal bipyramids that share corners with four equivalent Fe(2)O6 octahedra, corners with four equivalent Fe(1)O5 trigonal bipyramids,  an edgeedge with one Fe(1)O5 trigonal bipyramid, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-61°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form distorted FeO5 trigonal bipyramids that share corners with four equivalent Fe(2)O6 octahedra, corners with four equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O5 trigonal bipyramid, and edges with two equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-52°. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form FeO6 octahedra that share corners with four equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Fe(1)O5 trigonal bipyramids, edges with four equivalent Fe(2)O6 octahedra, and  a faceface with one Mg(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(1) atoms to form OMgFe3 tetrahedra that share corners with two equivalent O(1)MgFe3 tetrahedra,  a cornercorner with one O(4)Mg2Fe3 trigonal bipyramid, and edges with two equivalent O(4)Mg2Fe3 trigonal bipyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and three equivalent Fe(2) atoms to form distorted OMg2Fe3 trigonal bipyramids that share  a cornercorner with one O(1)MgFe3 tetrahedra, edges with two equivalent O(1)MgFe3 tetrahedra, and edges with four equivalent O(4)Mg2Fe3 trigonal bipyramids.
MgFe2O4 crystallizes in the triclinic P-1 space group. Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO5 trigonal bipyramids that share corners with four equivalent Fe(2)O6 octahedra, corners with four equivalent Fe(1)O5 trigonal bipyramids,  an edgeedge with one Fe(1)O5 trigonal bipyramid, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-61°. The Mg(1)-O(1) bond length is 2.08 Å. There is one shorter (2.03 Å) and one longer (2.05 Å) Mg(1)-O(3) bond length. Both Mg(1)-O(4) bond lengths are 2.08 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form distorted FeO5 trigonal bipyramids that share corners with four equivalent Fe(2)O6 octahedra, corners with four equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O5 trigonal bipyramid, and edges with two equivalent Fe(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-52°. The Fe(1)-O(2) bond length is 1.92 Å. Both Fe(1)-O(1) bond lengths are 1.99 Å. There is one shorter (2.05 Å) and one longer (2.08 Å) Fe(1)-O(3) bond length. In the second Fe site, Fe(2) is bonded to one O(1), two equivalent O(2), and three equivalent O(4) atoms to form FeO6 octahedra that share corners with four equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Fe(1)O5 trigonal bipyramids, edges with four equivalent Fe(2)O6 octahedra, and  a faceface with one Mg(1)O5 trigonal bipyramid. The Fe(2)-O(1) bond length is 2.08 Å. There is one shorter (1.95 Å) and one longer (1.96 Å) Fe(2)-O(2) bond length. There are a spread of Fe(2)-O(4) bond distances ranging from 2.02-2.18 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Fe(2), and two equivalent Fe(1) atoms to form OMgFe3 tetrahedra that share corners with two equivalent O(1)MgFe3 tetrahedra,  a cornercorner with one O(4)Mg2Fe3 trigonal bipyramid, and edges with two equivalent O(4)Mg2Fe3 trigonal bipyramids. In the second O site, O(2) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Fe(2) atoms. In the third O site, O(3) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and three equivalent Fe(2) atoms to form distorted OMg2Fe3 trigonal bipyramids that share  a cornercorner with one O(1)MgFe3 tetrahedra, edges with two equivalent O(1)MgFe3 tetrahedra, and edges with four equivalent O(4)Mg2Fe3 trigonal bipyramids.