MgMo3O8 is Hydrophilite-derived structured and crystallizes in the orthorhombic Cmc2_1 space group. Mg(1) is bonded to one O(3), one O(5), two equivalent O(4), and two equivalent O(6) atoms to form MgO6 octahedra that share corners with two equivalent Mo(1)O6 octahedra, corners with four equivalent Mo(2)O6 octahedra,  an edgeedge with one Mo(1)O6 octahedra, and edges with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-54°. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(2), two equivalent O(4), and two equivalent O(6) atoms to form distorted MoO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, and edges with four equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles are 54°. In the second Mo site, Mo(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form MoO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mo(1)O6 octahedra, and edges with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-53°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Mo(1) and two equivalent Mo(2) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mo(1) and two equivalent Mo(2) atoms. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Mg(1) and two equivalent Mo(2) atoms. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Mo(1), and one Mo(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Mg(1) and two equivalent Mo(2) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Mo(1), and one Mo(2) atom.
MgMo3O8 is Hydrophilite-derived structured and crystallizes in the orthorhombic Cmc2_1 space group. Mg(1) is bonded to one O(3), one O(5), two equivalent O(4), and two equivalent O(6) atoms to form MgO6 octahedra that share corners with two equivalent Mo(1)O6 octahedra, corners with four equivalent Mo(2)O6 octahedra,  an edgeedge with one Mo(1)O6 octahedra, and edges with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-54°. The Mg(1)-O(3) bond length is 2.15 Å. The Mg(1)-O(5) bond length is 2.10 Å. Both Mg(1)-O(4) bond lengths are 2.20 Å. Both Mg(1)-O(6) bond lengths are 2.11 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(1), one O(2), two equivalent O(4), and two equivalent O(6) atoms to form distorted MoO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, and edges with four equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles are 54°. The Mo(1)-O(1) bond length is 2.12 Å. The Mo(1)-O(2) bond length is 2.16 Å. Both Mo(1)-O(4) bond lengths are 2.08 Å. Both Mo(1)-O(6) bond lengths are 2.03 Å. In the second Mo site, Mo(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form MoO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mo(1)O6 octahedra, and edges with two equivalent Mo(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-53°. The Mo(2)-O(1) bond length is 2.04 Å. The Mo(2)-O(2) bond length is 2.06 Å. The Mo(2)-O(3) bond length is 2.02 Å. The Mo(2)-O(4) bond length is 1.92 Å. The Mo(2)-O(5) bond length is 2.05 Å. The Mo(2)-O(6) bond length is 2.01 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Mo(1) and two equivalent Mo(2) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mo(1) and two equivalent Mo(2) atoms. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Mg(1) and two equivalent Mo(2) atoms. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Mg(1), one Mo(1), and one Mo(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Mg(1) and two equivalent Mo(2) atoms. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Mo(1), and one Mo(2) atom.