MgMnSiO5 crystallizes in the triclinic P1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one O(10), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(9) atom. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(4), one O(6), one O(7), and one O(9) atom to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. In the second Mn site, Mn(2) is bonded to one O(1), one O(10), one O(2), one O(3), one O(5), and one O(8) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(3), one O(4), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and corners with two equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. In the second Si site, Si(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and corners with two equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(2), one Mn(1), and one Mn(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mg(1), one Mn(1), and one Mn(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mn(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mn(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mn(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mn(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Mg(2), one Mn(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Mg(2), one Mn(2), and one Si(2) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Mg(1), one Mn(1), and one Si(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Mn(2), and one Si(1) atom.
MgMnSiO5 crystallizes in the triclinic P1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one O(10), one O(2), one O(3), one O(4), one O(5), one O(6), and one O(9) atom. The Mg(1)-O(10) bond length is 2.21 Å. The Mg(1)-O(2) bond length is 2.01 Å. The Mg(1)-O(3) bond length is 2.26 Å. The Mg(1)-O(4) bond length is 2.25 Å. The Mg(1)-O(5) bond length is 2.55 Å. The Mg(1)-O(6) bond length is 2.63 Å. The Mg(1)-O(9) bond length is 2.25 Å. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. The Mg(2)-O(1) bond length is 2.01 Å. The Mg(2)-O(3) bond length is 2.57 Å. The Mg(2)-O(4) bond length is 2.61 Å. The Mg(2)-O(5) bond length is 2.27 Å. The Mg(2)-O(6) bond length is 2.24 Å. The Mg(2)-O(7) bond length is 2.24 Å. The Mg(2)-O(8) bond length is 2.21 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(4), one O(6), one O(7), and one O(9) atom to form MnO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. The Mn(1)-O(1) bond length is 1.88 Å. The Mn(1)-O(2) bond length is 1.88 Å. The Mn(1)-O(4) bond length is 1.95 Å. The Mn(1)-O(6) bond length is 1.95 Å. The Mn(1)-O(7) bond length is 1.92 Å. The Mn(1)-O(9) bond length is 1.92 Å. In the second Mn site, Mn(2) is bonded to one O(1), one O(10), one O(2), one O(3), one O(5), and one O(8) atom to form MnO6 octahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. The Mn(2)-O(1) bond length is 1.88 Å. The Mn(2)-O(10) bond length is 1.93 Å. The Mn(2)-O(2) bond length is 1.88 Å. The Mn(2)-O(3) bond length is 1.95 Å. The Mn(2)-O(5) bond length is 1.95 Å. The Mn(2)-O(8) bond length is 1.92 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(3), one O(4), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and corners with two equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. The Si(1)-O(10) bond length is 1.64 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.65 Å. The Si(1)-O(9) bond length is 1.64 Å. In the second Si site, Si(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and corners with two equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-56°. The Si(2)-O(5) bond length is 1.65 Å. The Si(2)-O(6) bond length is 1.65 Å. The Si(2)-O(7) bond length is 1.64 Å. The Si(2)-O(8) bond length is 1.64 Å. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(2), one Mn(1), and one Mn(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mg(1), one Mn(1), and one Mn(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mn(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mn(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mn(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Mg(1), one Mg(2), one Mn(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Mg(2), one Mn(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Mg(2), one Mn(2), and one Si(2) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Mg(1), one Mn(1), and one Si(1) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Mn(2), and one Si(1) atom.