Mg2Sn3O8 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Sn(1)O6 octahedra, corners with three equivalent Mg(2)O4 trigonal pyramids, and edges with three equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. In the second Mg site, Mg(2) is bonded to one O(4) and three equivalent O(2) atoms to form MgO4 trigonal pyramids that share corners with three equivalent Mg(1)O6 octahedra and corners with nine equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-65°. Sn(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form SnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent Mg(2)O4 trigonal pyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with four equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Sn(1) atoms. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and two equivalent Sn(1) atoms to form distorted OMg2Sn2 tetrahedra that share corners with two equivalent O(2)Mg2Sn2 tetrahedra,  a cornercorner with one O(4)MgSn3 trigonal pyramid, edges with two equivalent O(2)Mg2Sn2 tetrahedra, and  an edgeedge with one O(4)MgSn3 trigonal pyramid. In the third O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent Sn(1) atoms. In the fourth O site, O(4) is bonded to one Mg(2) and three equivalent Sn(1) atoms to form a mixture of distorted corner and edge-sharing OMgSn3 trigonal pyramids.
Mg2Sn3O8 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Sn(1)O6 octahedra, corners with three equivalent Mg(2)O4 trigonal pyramids, and edges with three equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. All Mg(1)-O(1) bond lengths are 2.09 Å. All Mg(1)-O(2) bond lengths are 2.22 Å. In the second Mg site, Mg(2) is bonded to one O(4) and three equivalent O(2) atoms to form MgO4 trigonal pyramids that share corners with three equivalent Mg(1)O6 octahedra and corners with nine equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-65°. The Mg(2)-O(4) bond length is 2.09 Å. All Mg(2)-O(2) bond lengths are 2.05 Å. Sn(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form SnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent Mg(2)O4 trigonal pyramids,  an edgeedge with one Mg(1)O6 octahedra, and edges with four equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. The Sn(1)-O(3) bond length is 2.10 Å. The Sn(1)-O(4) bond length is 2.17 Å. Both Sn(1)-O(1) bond lengths are 2.07 Å. Both Sn(1)-O(2) bond lengths are 2.13 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Sn(1) atoms. In the second O site, O(2) is bonded to one Mg(1), one Mg(2), and two equivalent Sn(1) atoms to form distorted OMg2Sn2 tetrahedra that share corners with two equivalent O(2)Mg2Sn2 tetrahedra,  a cornercorner with one O(4)MgSn3 trigonal pyramid, edges with two equivalent O(2)Mg2Sn2 tetrahedra, and  an edgeedge with one O(4)MgSn3 trigonal pyramid. In the third O site, O(3) is bonded in a distorted T-shaped geometry to three equivalent Sn(1) atoms. In the fourth O site, O(4) is bonded to one Mg(2) and three equivalent Sn(1) atoms to form a mixture of distorted corner and edge-sharing OMgSn3 trigonal pyramids.