CaAlB3O7 crystallizes in the orthorhombic Cmme space group. Ca(1) is bonded in a q6 geometry to two equivalent O(3), four equivalent O(1), and four equivalent O(2) atoms. Al(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form AlO6 octahedra that share corners with two equivalent B(1)O4 tetrahedra, corners with four equivalent B(2)O4 tetrahedra, and edges with two equivalent B(1)O4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form BO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one B(1)O4 tetrahedra, corners with two equivalent B(2)O4 tetrahedra, and  an edgeedge with one Al(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. In the second B site, B(2) is bonded to four equivalent O(2) atoms to form BO4 tetrahedra that share corners with four equivalent Al(1)O6 octahedra and corners with four equivalent B(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 61°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Ca(1), one Al(1), and one B(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Al(1), one B(1), and one B(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and two equivalent B(1) atoms.
CaAlB3O7 crystallizes in the orthorhombic Cmme space group. Ca(1) is bonded in a q6 geometry to two equivalent O(3), four equivalent O(1), and four equivalent O(2) atoms. Both Ca(1)-O(3) bond lengths are 2.48 Å. All Ca(1)-O(1) bond lengths are 2.64 Å. All Ca(1)-O(2) bond lengths are 2.61 Å. Al(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form AlO6 octahedra that share corners with two equivalent B(1)O4 tetrahedra, corners with four equivalent B(2)O4 tetrahedra, and edges with two equivalent B(1)O4 tetrahedra. Both Al(1)-O(1) bond lengths are 1.84 Å. All Al(1)-O(2) bond lengths are 1.97 Å. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form BO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one B(1)O4 tetrahedra, corners with two equivalent B(2)O4 tetrahedra, and  an edgeedge with one Al(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. The B(1)-O(1) bond length is 1.40 Å. The B(1)-O(3) bond length is 1.45 Å. Both B(1)-O(2) bond lengths are 1.56 Å. In the second B site, B(2) is bonded to four equivalent O(2) atoms to form BO4 tetrahedra that share corners with four equivalent Al(1)O6 octahedra and corners with four equivalent B(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 61°. All B(2)-O(2) bond lengths are 1.49 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Ca(1), one Al(1), and one B(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Al(1), one B(1), and one B(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and two equivalent B(1) atoms.