MgAl2(PO4)3 is Keatite-derived structured and crystallizes in the monoclinic Cc space group. Mg(1) is bonded to one O(11), one O(6), one O(8), and one O(9) atom to form MgO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(10), one O(4), and one O(7) atom to form AlO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(12), one O(2), one O(3), and one O(5) atom to form AlO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(12), one O(4), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. In the second P site, P(2) is bonded to one O(11), one O(2), one O(5), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. In the third P site, P(3) is bonded to one O(1), one O(10), one O(3), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. There are twelve inequivalent O sites. In the first O site, O(9) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the second O site, O(10) is bonded in a bent 150 degrees geometry to one Al(1) and one P(3) atom. In the third O site, O(11) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(2) atom. In the fourth O site, O(12) is bonded in a bent 150 degrees geometry to one Al(2) and one P(1) atom. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one P(3) atom. In the sixth O site, O(2) is bonded in a linear geometry to one Al(2) and one P(2) atom. In the seventh O site, O(3) is bonded in a bent 150 degrees geometry to one Al(2) and one P(3) atom. In the eighth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom. In the ninth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(2) and one P(2) atom. In the tenth O site, O(6) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(3) atom. In the eleventh O site, O(7) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom. In the twelfth O site, O(8) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(2) atom.
MgAl2(PO4)3 is Keatite-derived structured and crystallizes in the monoclinic Cc space group. Mg(1) is bonded to one O(11), one O(6), one O(8), and one O(9) atom to form MgO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The Mg(1)-O(11) bond length is 1.92 Å. The Mg(1)-O(6) bond length is 1.89 Å. The Mg(1)-O(8) bond length is 1.93 Å. The Mg(1)-O(9) bond length is 1.90 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(10), one O(4), and one O(7) atom to form AlO4 tetrahedra that share corners with two equivalent P(1)O4 tetrahedra and corners with two equivalent P(3)O4 tetrahedra. The Al(1)-O(1) bond length is 1.74 Å. The Al(1)-O(10) bond length is 1.74 Å. The Al(1)-O(4) bond length is 1.75 Å. The Al(1)-O(7) bond length is 1.76 Å. In the second Al site, Al(2) is bonded to one O(12), one O(2), one O(3), and one O(5) atom to form AlO4 tetrahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, and corners with two equivalent P(2)O4 tetrahedra. The Al(2)-O(12) bond length is 1.75 Å. The Al(2)-O(2) bond length is 1.75 Å. The Al(2)-O(3) bond length is 1.74 Å. The Al(2)-O(5) bond length is 1.75 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded to one O(12), one O(4), one O(7), and one O(9) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. The P(1)-O(12) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.55 Å. The P(1)-O(7) bond length is 1.55 Å. The P(1)-O(9) bond length is 1.51 Å. In the second P site, P(2) is bonded to one O(11), one O(2), one O(5), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. The P(2)-O(11) bond length is 1.52 Å. The P(2)-O(2) bond length is 1.54 Å. The P(2)-O(5) bond length is 1.54 Å. The P(2)-O(8) bond length is 1.53 Å. In the third P site, P(3) is bonded to one O(1), one O(10), one O(3), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. The P(3)-O(1) bond length is 1.54 Å. The P(3)-O(10) bond length is 1.54 Å. The P(3)-O(3) bond length is 1.54 Å. The P(3)-O(6) bond length is 1.51 Å. There are twelve inequivalent O sites. In the first O site, O(9) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(1) atom. In the second O site, O(10) is bonded in a bent 150 degrees geometry to one Al(1) and one P(3) atom. In the third O site, O(11) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(2) atom. In the fourth O site, O(12) is bonded in a bent 150 degrees geometry to one Al(2) and one P(1) atom. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one P(3) atom. In the sixth O site, O(2) is bonded in a linear geometry to one Al(2) and one P(2) atom. In the seventh O site, O(3) is bonded in a bent 150 degrees geometry to one Al(2) and one P(3) atom. In the eighth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom. In the ninth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(2) and one P(2) atom. In the tenth O site, O(6) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(3) atom. In the eleventh O site, O(7) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom. In the twelfth O site, O(8) is bonded in a bent 150 degrees geometry to one Mg(1) and one P(2) atom.