MgMn3HO6 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(4), one O(6), two equivalent O(2), and two equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and  a faceface with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to one O(2), one O(5), two equivalent O(4), and two equivalent O(6) atoms. In the third Mn site, Mn(3) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(3), and two equivalent O(5) atoms. H(1) is bonded in a single-bond geometry to one O(5) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mn(3) and two equivalent Mn(1) atoms. In the second O site, O(2) is bonded to two equivalent Mg(1), one Mn(2), and two equivalent Mn(1) atoms to form distorted OMg2Mn3 trigonal bipyramids that share corners with two equivalent O(4)MgMn3 trigonal pyramids, edges with two equivalent O(6)MgMn3 tetrahedra, edges with two equivalent O(2)Mg2Mn3 trigonal bipyramids, and edges with two equivalent O(4)MgMn3 trigonal pyramids. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1) and two equivalent Mn(3) atoms. In the fourth O site, O(4) is bonded to one Mg(1), one Mn(1), and two equivalent Mn(2) atoms to form OMgMn3 trigonal pyramids that share corners with three equivalent O(6)MgMn3 tetrahedra, corners with two equivalent O(2)Mg2Mn3 trigonal bipyramids, corners with two equivalent O(4)MgMn3 trigonal pyramids,  an edgeedge with one O(6)MgMn3 tetrahedra, and edges with two equivalent O(2)Mg2Mn3 trigonal bipyramids. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Mg(1), one Mn(2), two equivalent Mn(3), and one H(1) atom. In the sixth O site, O(6) is bonded to one Mg(1), one Mn(3), and two equivalent Mn(2) atoms to form distorted OMgMn3 tetrahedra that share corners with two equivalent O(6)MgMn3 tetrahedra, corners with three equivalent O(4)MgMn3 trigonal pyramids, edges with two equivalent O(2)Mg2Mn3 trigonal bipyramids, and  an edgeedge with one O(4)MgMn3 trigonal pyramid.
MgMn3HO6 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(4), one O(6), two equivalent O(2), and two equivalent O(5) atoms to form distorted MgO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and  a faceface with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. The Mg(1)-O(4) bond length is 2.05 Å. The Mg(1)-O(6) bond length is 1.99 Å. There is one shorter (2.28 Å) and one longer (2.30 Å) Mg(1)-O(2) bond length. Both Mg(1)-O(5) bond lengths are 2.06 Å. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MnO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mn(1)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. The Mn(1)-O(3) bond length is 1.99 Å. The Mn(1)-O(4) bond length is 2.06 Å. There is one shorter (1.95 Å) and one longer (1.96 Å) Mn(1)-O(1) bond length. Both Mn(1)-O(2) bond lengths are 2.07 Å. In the second Mn site, Mn(2) is bonded in a 6-coordinate geometry to one O(2), one O(5), two equivalent O(4), and two equivalent O(6) atoms. The Mn(2)-O(2) bond length is 2.12 Å. The Mn(2)-O(5) bond length is 2.62 Å. There is one shorter (1.96 Å) and one longer (1.97 Å) Mn(2)-O(4) bond length. There is one shorter (2.00 Å) and one longer (2.01 Å) Mn(2)-O(6) bond length. In the third Mn site, Mn(3) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(3), and two equivalent O(5) atoms. The Mn(3)-O(1) bond length is 2.08 Å. The Mn(3)-O(6) bond length is 2.16 Å. Both Mn(3)-O(3) bond lengths are 1.98 Å. There is one shorter (2.51 Å) and one longer (2.56 Å) Mn(3)-O(5) bond length. H(1) is bonded in a single-bond geometry to one O(5) atom. The H(1)-O(5) bond length is 0.99 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mn(3) and two equivalent Mn(1) atoms. In the second O site, O(2) is bonded to two equivalent Mg(1), one Mn(2), and two equivalent Mn(1) atoms to form distorted OMg2Mn3 trigonal bipyramids that share corners with two equivalent O(4)MgMn3 trigonal pyramids, edges with two equivalent O(6)MgMn3 tetrahedra, edges with two equivalent O(2)Mg2Mn3 trigonal bipyramids, and edges with two equivalent O(4)MgMn3 trigonal pyramids. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1) and two equivalent Mn(3) atoms. In the fourth O site, O(4) is bonded to one Mg(1), one Mn(1), and two equivalent Mn(2) atoms to form OMgMn3 trigonal pyramids that share corners with three equivalent O(6)MgMn3 tetrahedra, corners with two equivalent O(2)Mg2Mn3 trigonal bipyramids, corners with two equivalent O(4)MgMn3 trigonal pyramids,  an edgeedge with one O(6)MgMn3 tetrahedra, and edges with two equivalent O(2)Mg2Mn3 trigonal bipyramids. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Mg(1), one Mn(2), two equivalent Mn(3), and one H(1) atom. In the sixth O site, O(6) is bonded to one Mg(1), one Mn(3), and two equivalent Mn(2) atoms to form distorted OMgMn3 tetrahedra that share corners with two equivalent O(6)MgMn3 tetrahedra, corners with three equivalent O(4)MgMn3 trigonal pyramids, edges with two equivalent O(2)Mg2Mn3 trigonal bipyramids, and  an edgeedge with one O(4)MgMn3 trigonal pyramid.