MgAl(PO4)O crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. Al(1) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form AlO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. P(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with four equivalent Mg(1)O5 trigonal bipyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one P(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Mg(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Al(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1) and two equivalent Al(1) atoms. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom.
MgAl(PO4)O crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The Mg(1)-O(4) bond length is 2.01 Å. There is one shorter (2.02 Å) and one longer (2.07 Å) Mg(1)-O(1) bond length. There is one shorter (2.04 Å) and one longer (2.10 Å) Mg(1)-O(2) bond length. Al(1) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form AlO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent Mg(1)O5 trigonal bipyramids. The Al(1)-O(3) bond length is 1.76 Å. The Al(1)-O(5) bond length is 1.75 Å. There is one shorter (1.73 Å) and one longer (1.74 Å) Al(1)-O(4) bond length. P(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with four equivalent Mg(1)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.53 Å. The P(1)-O(2) bond length is 1.53 Å. The P(1)-O(3) bond length is 1.53 Å. The P(1)-O(5) bond length is 1.52 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Mg(1) and one P(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to two equivalent Mg(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Al(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1) and two equivalent Al(1) atoms. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom.