MnAlSiO5 crystallizes in the orthorhombic Pnnm space group. Mn(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, corners with four equivalent Al(1)O5 trigonal bipyramids, and edges with two equivalent Mn(1)O6 octahedra. Al(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form AlO5 trigonal bipyramids that share corners with four equivalent Mn(1)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Al(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 49-63°. Si(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with four equivalent Mn(1)O6 octahedra and corners with four equivalent Al(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 55-73°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Al(1) and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one Al(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one Si(1) atom.
MnAlSiO5 crystallizes in the orthorhombic Pnnm space group. Mn(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, corners with four equivalent Al(1)O5 trigonal bipyramids, and edges with two equivalent Mn(1)O6 octahedra. Both Mn(1)-O(2) bond lengths are 1.91 Å. Both Mn(1)-O(3) bond lengths are 2.34 Å. Both Mn(1)-O(4) bond lengths are 1.95 Å. Al(1) is bonded to one O(2), two equivalent O(1), and two equivalent O(3) atoms to form AlO5 trigonal bipyramids that share corners with four equivalent Mn(1)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Al(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 49-63°. The Al(1)-O(2) bond length is 1.88 Å. There is one shorter (1.87 Å) and one longer (1.96 Å) Al(1)-O(1) bond length. Both Al(1)-O(3) bond lengths are 1.82 Å. Si(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with four equivalent Mn(1)O6 octahedra and corners with four equivalent Al(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 55-73°. The Si(1)-O(1) bond length is 1.67 Å. The Si(1)-O(4) bond length is 1.66 Å. Both Si(1)-O(3) bond lengths are 1.64 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to two equivalent Al(1) and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one Al(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one Si(1) atom.