MgSiO3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Mg(2)O4 tetrahedra and corners with three equivalent Si(1)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form MgO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Mg(2)O4 tetrahedra, and corners with three equivalent Si(1)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O4 tetrahedra and corners with three equivalent Mg(2)O4 tetrahedra. In the second Si site, Si(2) is bonded in a trigonal planar geometry to one O(2), one O(5), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mg(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to two equivalent Mg(2) and one Si(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mg(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(2) and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(1) and one Si(2) atom.
MgSiO3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), one O(2), one O(4), and one O(6) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Mg(2)O4 tetrahedra and corners with three equivalent Si(1)O4 tetrahedra. The Mg(1)-O(1) bond length is 2.00 Å. The Mg(1)-O(2) bond length is 2.17 Å. The Mg(1)-O(4) bond length is 1.93 Å. The Mg(1)-O(6) bond length is 1.97 Å. In the second Mg site, Mg(2) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form MgO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Mg(2)O4 tetrahedra, and corners with three equivalent Si(1)O4 tetrahedra. The Mg(2)-O(1) bond length is 2.00 Å. The Mg(2)-O(5) bond length is 1.97 Å. There is one shorter (1.99 Å) and one longer (2.00 Å) Mg(2)-O(3) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O4 tetrahedra and corners with three equivalent Mg(2)O4 tetrahedra. The Si(1)-O(1) bond length is 1.64 Å. The Si(1)-O(2) bond length is 1.77 Å. The Si(1)-O(3) bond length is 1.64 Å. The Si(1)-O(4) bond length is 1.60 Å. In the second Si site, Si(2) is bonded in a trigonal planar geometry to one O(2), one O(5), and one O(6) atom. The Si(2)-O(2) bond length is 1.63 Å. The Si(2)-O(5) bond length is 1.56 Å. The Si(2)-O(6) bond length is 1.57 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mg(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to two equivalent Mg(2) and one Si(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mg(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(2) and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(1) and one Si(2) atom.