CaMg2(SO4)3 crystallizes in the hexagonal P6_3/m space group. Ca(1) is bonded in a distorted hexagonal planar geometry to six equivalent O(2) atoms. Mg(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra and  a faceface with one Mg(1)O6 octahedra. S(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-49°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Mg(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one S(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one S(1) atom.
CaMg2(SO4)3 crystallizes in the hexagonal P6_3/m space group. Ca(1) is bonded in a distorted hexagonal planar geometry to six equivalent O(2) atoms. All Ca(1)-O(2) bond lengths are 2.43 Å. Mg(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra and  a faceface with one Mg(1)O6 octahedra. All Mg(1)-O(1) bond lengths are 2.17 Å. All Mg(1)-O(3) bond lengths are 2.04 Å. S(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SO4 tetrahedra that share corners with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-49°. The S(1)-O(1) bond length is 1.50 Å. The S(1)-O(2) bond length is 1.49 Å. Both S(1)-O(3) bond lengths are 1.47 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to two equivalent Mg(1) and one S(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one S(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(1) and one S(1) atom.