FeAl(PO4)O crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(5) atoms to form FeO5 trigonal bipyramids that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, and  an edgeedge with one Fe(1)O5 trigonal bipyramid. Al(1) is bonded to one O(2), one O(3), and two equivalent O(1) 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 Fe(1)O5 trigonal bipyramids. P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with four equivalent Fe(1)O5 trigonal bipyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 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 two equivalent Fe(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one P(1) atom.
FeAl(PO4)O crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(5) atoms to form FeO5 trigonal bipyramids that share corners with two equivalent Al(1)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent Fe(1)O5 trigonal bipyramids, and  an edgeedge with one Fe(1)O5 trigonal bipyramid. The Fe(1)-O(1) bond length is 2.07 Å. There is one shorter (2.14 Å) and one longer (2.17 Å) Fe(1)-O(4) bond length. There is one shorter (2.06 Å) and one longer (2.20 Å) Fe(1)-O(5) bond length. Al(1) is bonded to one O(2), one O(3), and two equivalent O(1) 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 Fe(1)O5 trigonal bipyramids. The Al(1)-O(2) bond length is 1.76 Å. The Al(1)-O(3) bond length is 1.78 Å. Both Al(1)-O(1) bond lengths are 1.76 Å. P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with four equivalent Fe(1)O5 trigonal bipyramids. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(5) bond length is 1.56 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Fe(1) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom. In the third O site, O(3) is bonded in a bent 150 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 two equivalent Fe(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to two equivalent Fe(1) and one P(1) atom.