MgSiO3 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(2)O6 octahedra, corners with two equivalent Si(2)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Si(1)O5 trigonal bipyramid, edges with two equivalent Si(2)O5 trigonal bipyramids, and  a faceface with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-29°. In the second Mg site, Mg(2) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Mg(2)O6 octahedra,  an edgeedge with one Si(2)O5 trigonal bipyramid, edges with two equivalent Si(1)O5 trigonal bipyramids, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-29°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(3) atoms to form SiO5 trigonal bipyramids that share corners with two equivalent Mg(2)O6 octahedra,  a cornercorner with one Si(2)O5 trigonal bipyramid, corners with two equivalent Si(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and  an edgeedge with one Si(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 33-39°. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form distorted SiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Si(1)O5 trigonal bipyramid, corners with two equivalent Si(2)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 31-37°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Mg(2) atoms. In the second O site, O(2) is bonded in a square co-planar geometry to one Mg(1), one Mg(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(2) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent Si(2) atoms to form distorted edge-sharing OMg2Si2 trigonal pyramids. In the fifth O site, O(5) is bonded in an L-shaped geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Mg(1), one Mg(2), one Si(1), and one Si(2) atom.
MgSiO3 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(2)O6 octahedra, corners with two equivalent Si(2)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Si(1)O5 trigonal bipyramid, edges with two equivalent Si(2)O5 trigonal bipyramids, and  a faceface with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-29°. The Mg(1)-O(2) bond length is 2.29 Å. The Mg(1)-O(6) bond length is 2.20 Å. There is one shorter (1.93 Å) and one longer (1.95 Å) Mg(1)-O(1) bond length. There is one shorter (2.08 Å) and one longer (2.15 Å) Mg(1)-O(4) bond length. In the second Mg site, Mg(2) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Mg(2)O6 octahedra,  an edgeedge with one Si(2)O5 trigonal bipyramid, edges with two equivalent Si(1)O5 trigonal bipyramids, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-29°. The Mg(2)-O(2) bond length is 2.27 Å. The Mg(2)-O(6) bond length is 2.20 Å. There is one shorter (1.92 Å) and one longer (1.96 Å) Mg(2)-O(1) bond length. There is one shorter (2.05 Å) and one longer (2.24 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(2), one O(5), one O(6), and two equivalent O(3) atoms to form SiO5 trigonal bipyramids that share corners with two equivalent Mg(2)O6 octahedra,  a cornercorner with one Si(2)O5 trigonal bipyramid, corners with two equivalent Si(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and  an edgeedge with one Si(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 33-39°. The Si(1)-O(2) bond length is 1.74 Å. The Si(1)-O(5) bond length is 1.71 Å. The Si(1)-O(6) bond length is 1.81 Å. There is one shorter (1.76 Å) and one longer (1.82 Å) Si(1)-O(3) bond length. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form distorted SiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Si(1)O5 trigonal bipyramid, corners with two equivalent Si(2)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 31-37°. The Si(2)-O(2) bond length is 1.76 Å. The Si(2)-O(5) bond length is 1.72 Å. The Si(2)-O(6) bond length is 1.79 Å. There is one shorter (1.77 Å) and one longer (1.82 Å) Si(2)-O(4) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Mg(2) atoms. In the second O site, O(2) is bonded in a square co-planar geometry to one Mg(1), one Mg(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(2) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent Si(2) atoms to form distorted edge-sharing OMg2Si2 trigonal pyramids. In the fifth O site, O(5) is bonded in an L-shaped geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Mg(1), one Mg(2), one Si(1), and one Si(2) atom.