MgSiO3 crystallizes in the monoclinic C2/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with three equivalent Mg(2)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with three equivalent Mg(1)O6 octahedra. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent Mg(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 27-61°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the third O site, O(3) is bonded to one Mg(1), two equivalent Mg(2), and one Si(1) atom to form a mixture of distorted edge and corner-sharing OMg3Si trigonal pyramids.
MgSiO3 crystallizes in the monoclinic C2/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with three equivalent Mg(2)O6 octahedra, and edges with two equivalent Si(1)O4 tetrahedra. Both Mg(1)-O(1) bond lengths are 2.30 Å. Both Mg(1)-O(2) bond lengths are 2.04 Å. Both Mg(1)-O(3) bond lengths are 2.05 Å. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with three equivalent Mg(1)O6 octahedra. Both Mg(2)-O(2) bond lengths are 2.00 Å. There are two shorter (2.06 Å) and two longer (2.19 Å) Mg(2)-O(3) bond lengths. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent Mg(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 27-61°. The Si(1)-O(2) bond length is 1.59 Å. The Si(1)-O(3) bond length is 1.61 Å. There is one shorter (1.65 Å) and one longer (1.67 Å) Si(1)-O(1) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the third O site, O(3) is bonded to one Mg(1), two equivalent Mg(2), and one Si(1) atom to form a mixture of distorted edge and corner-sharing OMg3Si trigonal pyramids.