CaMgSi2O6 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), one O(4), one O(5), two equivalent O(2), and two equivalent O(6) atoms. Mg(1) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with three equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form SiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Si(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 34-55°. In the second Si site, Si(2) is bonded to one O(1), one O(5), and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-62°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), two equivalent Mg(1), and one Si(2) atom. In the second O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and two equivalent Si(2) atoms. In the third O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Mg(1), and one Si(2) atom. In the fourth O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Ca(1) and two equivalent Si(1) atoms. In the fifth O site, O(3) is bonded in a distorted see-saw-like geometry to one Ca(1), one Mg(1), and two equivalent Si(1) atoms. In the sixth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Ca(1), two equivalent Mg(1), and one Si(1) atom.
CaMgSi2O6 crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), one O(4), one O(5), two equivalent O(2), and two equivalent O(6) atoms. The Ca(1)-O(1) bond length is 2.31 Å. The Ca(1)-O(3) bond length is 2.36 Å. The Ca(1)-O(4) bond length is 2.42 Å. The Ca(1)-O(5) bond length is 2.41 Å. There is one shorter (2.54 Å) and one longer (2.67 Å) Ca(1)-O(2) bond length. There is one shorter (2.61 Å) and one longer (3.00 Å) Ca(1)-O(6) bond length. Mg(1) is bonded to one O(1), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with three equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. The Mg(1)-O(1) bond length is 1.94 Å. The Mg(1)-O(3) bond length is 2.17 Å. There is one shorter (2.04 Å) and one longer (2.19 Å) Mg(1)-O(4) bond length. There is one shorter (2.08 Å) and one longer (2.11 Å) Mg(1)-O(5) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form SiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Si(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 34-55°. The Si(1)-O(4) bond length is 1.72 Å. There is one shorter (1.72 Å) and one longer (1.75 Å) Si(1)-O(2) bond length. There is one shorter (1.73 Å) and one longer (1.92 Å) Si(1)-O(3) bond length. In the second Si site, Si(2) is bonded to one O(1), one O(5), and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-62°. The Si(2)-O(1) bond length is 1.59 Å. The Si(2)-O(5) bond length is 1.62 Å. There is one shorter (1.69 Å) and one longer (1.70 Å) Si(2)-O(6) bond length. There are six inequivalent O sites. In the first O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), two equivalent Mg(1), and one Si(2) atom. In the second O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and two equivalent Si(2) atoms. In the third O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Mg(1), and one Si(2) atom. In the fourth O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Ca(1) and two equivalent Si(1) atoms. In the fifth O site, O(3) is bonded in a distorted see-saw-like geometry to one Ca(1), one Mg(1), and two equivalent Si(1) atoms. In the sixth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Ca(1), two equivalent Mg(1), and one Si(1) atom.