CaAlSiO5 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(3), and four equivalent O(2) atoms. Al(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form AlO6 octahedra that share corners with two equivalent Al(1)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. Si(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with four equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-53°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded to two equivalent Ca(1), one Al(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCa2AlSi tetrahedra. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ca(1), one Al(1), and one Si(1) atom.
CaAlSiO5 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(3), and four equivalent O(2) atoms. The Ca(1)-O(1) bond length is 2.31 Å. Both Ca(1)-O(3) bond lengths are 2.43 Å. There are two shorter (2.42 Å) and two longer (2.55 Å) Ca(1)-O(2) bond lengths. Al(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form AlO6 octahedra that share corners with two equivalent Al(1)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. Both Al(1)-O(1) bond lengths are 1.84 Å. Both Al(1)-O(2) bond lengths are 1.98 Å. Both Al(1)-O(3) bond lengths are 1.90 Å. Si(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with four equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-53°. Both Si(1)-O(2) bond lengths are 1.64 Å. Both Si(1)-O(3) bond lengths are 1.65 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded to two equivalent Ca(1), one Al(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCa2AlSi tetrahedra. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ca(1), one Al(1), and one Si(1) atom.