MgZn2(FeO2)4 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with four equivalent Fe(2)O6 octahedra and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. 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 two equivalent Mg(1)O6 octahedra and edges with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 59°. Zn(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Fe(2), two equivalent Fe(1), and one Zn(1) atom to form distorted OZnFe3 tetrahedra that share corners with four equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids, corners with two equivalent O(1)ZnFe3 tetrahedra, corners with four equivalent O(2)MgFe3 tetrahedra,  a cornercorner with one O(4)Zn2Fe3 trigonal bipyramid,  an edgeedge with one O(3)Mg2Zn2Fe2 pentagonal pyramid, and edges with two equivalent O(4)Zn2Fe3 trigonal bipyramids. In the second O site, O(2) is bonded to one Mg(1), one Fe(1), and two equivalent Fe(2) atoms to form distorted OMgFe3 tetrahedra that share corners with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids, corners with three equivalent O(2)MgFe3 tetrahedra, corners with four equivalent O(1)ZnFe3 tetrahedra, corners with four equivalent O(4)Zn2Fe3 trigonal bipyramids, edges with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids, and  an edgeedge with one O(4)Zn2Fe3 trigonal bipyramid. In the third O site, O(3) is bonded to two equivalent Mg(1), two equivalent Fe(1), and two equivalent Zn(1) atoms to form distorted OMg2Zn2Fe2 pentagonal pyramids that share corners with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids, corners with two equivalent O(2)MgFe3 tetrahedra, corners with four equivalent O(1)ZnFe3 tetrahedra, corners with two equivalent O(4)Zn2Fe3 trigonal bipyramids,  an edgeedge with one O(3)Mg2Zn2Fe2 pentagonal pyramid,  an edgeedge with one O(1)ZnFe3 tetrahedra, edges with two equivalent O(2)MgFe3 tetrahedra,  an edgeedge with one O(4)Zn2Fe3 trigonal bipyramid, and faces with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids. In the fourth O site, O(4) is bonded to three equivalent Fe(2) and two equivalent Zn(1) atoms to form distorted OZn2Fe3 trigonal bipyramids that share corners with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids,  a cornercorner with one O(1)ZnFe3 tetrahedra, corners with four equivalent O(2)MgFe3 tetrahedra,  an edgeedge with one O(3)Mg2Zn2Fe2 pentagonal pyramid,  an edgeedge with one O(2)MgFe3 tetrahedra, edges with two equivalent O(1)ZnFe3 tetrahedra, and edges with four equivalent O(4)Zn2Fe3 trigonal bipyramids.
MgZn2(FeO2)4 crystallizes in the monoclinic C2 space group. Mg(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with four equivalent Fe(2)O6 octahedra and edges with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 59°. Both Mg(1)-O(2) bond lengths are 2.18 Å. There are two shorter (2.19 Å) and two longer (2.20 Å) Mg(1)-O(3) bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(1), and two equivalent O(3) atoms. The Fe(1)-O(2) bond length is 2.09 Å. Both Fe(1)-O(1) bond lengths are 1.99 Å. Both Fe(1)-O(3) bond lengths are 2.33 Å. 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 two equivalent Mg(1)O6 octahedra and edges with four equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles are 59°. The Fe(2)-O(1) bond length is 2.11 Å. Both Fe(2)-O(2) bond lengths are 2.00 Å. There is one shorter (2.01 Å) and two longer (2.13 Å) Fe(2)-O(4) bond lengths. Zn(1) is bonded in a 5-coordinate geometry to one O(1), two equivalent O(3), and two equivalent O(4) atoms. The Zn(1)-O(1) bond length is 2.07 Å. Both Zn(1)-O(3) bond lengths are 2.14 Å. There is one shorter (2.11 Å) and one longer (2.12 Å) Zn(1)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Fe(2), two equivalent Fe(1), and one Zn(1) atom to form distorted OZnFe3 tetrahedra that share corners with four equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids, corners with two equivalent O(1)ZnFe3 tetrahedra, corners with four equivalent O(2)MgFe3 tetrahedra,  a cornercorner with one O(4)Zn2Fe3 trigonal bipyramid,  an edgeedge with one O(3)Mg2Zn2Fe2 pentagonal pyramid, and edges with two equivalent O(4)Zn2Fe3 trigonal bipyramids. In the second O site, O(2) is bonded to one Mg(1), one Fe(1), and two equivalent Fe(2) atoms to form distorted OMgFe3 tetrahedra that share corners with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids, corners with three equivalent O(2)MgFe3 tetrahedra, corners with four equivalent O(1)ZnFe3 tetrahedra, corners with four equivalent O(4)Zn2Fe3 trigonal bipyramids, edges with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids, and  an edgeedge with one O(4)Zn2Fe3 trigonal bipyramid. In the third O site, O(3) is bonded to two equivalent Mg(1), two equivalent Fe(1), and two equivalent Zn(1) atoms to form distorted OMg2Zn2Fe2 pentagonal pyramids that share corners with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids, corners with two equivalent O(2)MgFe3 tetrahedra, corners with four equivalent O(1)ZnFe3 tetrahedra, corners with two equivalent O(4)Zn2Fe3 trigonal bipyramids,  an edgeedge with one O(3)Mg2Zn2Fe2 pentagonal pyramid,  an edgeedge with one O(1)ZnFe3 tetrahedra, edges with two equivalent O(2)MgFe3 tetrahedra,  an edgeedge with one O(4)Zn2Fe3 trigonal bipyramid, and faces with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids. In the fourth O site, O(4) is bonded to three equivalent Fe(2) and two equivalent Zn(1) atoms to form distorted OZn2Fe3 trigonal bipyramids that share corners with two equivalent O(3)Mg2Zn2Fe2 pentagonal pyramids,  a cornercorner with one O(1)ZnFe3 tetrahedra, corners with four equivalent O(2)MgFe3 tetrahedra,  an edgeedge with one O(3)Mg2Zn2Fe2 pentagonal pyramid,  an edgeedge with one O(2)MgFe3 tetrahedra, edges with two equivalent O(1)ZnFe3 tetrahedra, and edges with four equivalent O(4)Zn2Fe3 trigonal bipyramids.