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(3), one O(5), and one O(6) atom to form MgO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Mg(1)O4 tetrahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(3), one O(6), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(2) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), 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(3), one O(5), and one O(6) atom to form MgO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The Mg(1)-O(2) bond length is 1.98 Å. The Mg(1)-O(3) bond length is 1.99 Å. The Mg(1)-O(5) bond length is 1.95 Å. The Mg(1)-O(6) bond length is 2.01 Å. In the second Mg site, Mg(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Mg(1)O4 tetrahedra,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. The Mg(2)-O(1) bond length is 2.15 Å. The Mg(2)-O(2) bond length is 2.01 Å. The Mg(2)-O(3) bond length is 1.99 Å. The Mg(2)-O(5) bond length is 2.19 Å. The Mg(2)-O(6) bond length is 2.05 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The Si(1)-O(2) bond length is 1.62 Å. The Si(1)-O(5) bond length is 1.60 Å. There is one shorter (1.69 Å) and one longer (1.71 Å) Si(1)-O(1) bond length. In the second Si site, Si(2) is bonded to one O(3), one O(6), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The Si(2)-O(3) bond length is 1.66 Å. The Si(2)-O(6) bond length is 1.64 Å. There is one shorter (1.65 Å) and one longer (1.66 Å) Si(2)-O(4) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(2) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom.