NaMgAl3Si3O16 crystallizes in the monoclinic Cc space group. Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(14), one O(15), one O(16), one O(2), and one O(3) atom. Mg(1) is bonded to one O(13), one O(14), one O(4), one O(5), and one O(6) atom to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. There are three 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 Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. In the second Al site, Al(2) is bonded to one O(11), one O(12), one O(2), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. In the third Al site, Al(3) is bonded to one O(3), one O(5), one O(8), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(12), one O(3), one O(6), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Al(2)O4 tetrahedra, corners with two equivalent Al(3)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(10), one O(11), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, corners with two equivalent Al(1)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. In the third Si site, Si(3) is bonded to one O(2), one O(4), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, corners with two equivalent Al(1)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Al(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Al(2), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(1), one Al(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1), one Al(1), and one Si(3) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Al(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Al(2), and one Si(1) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(3) and one Si(3) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Al(3) and one Si(1) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(2) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(1) atom. In the thirteenth O site, O(13) is bonded in a single-bond geometry to one Mg(1) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Na(1) and one Mg(1) atom. In the fifteenth O site, O(15) is bonded in a distorted single-bond geometry to one Na(1) and one O(16) atom. In the sixteenth O site, O(16) is bonded in an L-shaped geometry to one Na(1) and one O(15) atom.
NaMgAl3Si3O16 crystallizes in the monoclinic Cc space group. Na(1) is bonded in a 5-coordinate geometry to one O(1), one O(14), one O(15), one O(16), one O(2), and one O(3) atom. The Na(1)-O(1) bond length is 2.33 Å. The Na(1)-O(14) bond length is 2.52 Å. The Na(1)-O(15) bond length is 2.88 Å. The Na(1)-O(16) bond length is 2.71 Å. The Na(1)-O(2) bond length is 2.43 Å. The Na(1)-O(3) bond length is 2.30 Å. Mg(1) is bonded to one O(13), one O(14), one O(4), one O(5), and one O(6) atom to form distorted MgO5 trigonal bipyramids that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The Mg(1)-O(13) bond length is 2.09 Å. The Mg(1)-O(14) bond length is 2.08 Å. The Mg(1)-O(4) bond length is 2.10 Å. The Mg(1)-O(5) bond length is 2.23 Å. The Mg(1)-O(6) bond length is 2.09 Å. There are three 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 Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. The Al(1)-O(1) bond length is 1.76 Å. The Al(1)-O(10) bond length is 1.73 Å. The Al(1)-O(4) bond length is 1.80 Å. The Al(1)-O(7) bond length is 1.74 Å. In the second Al site, Al(2) is bonded to one O(11), one O(12), one O(2), and one O(6) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. The Al(2)-O(11) bond length is 1.73 Å. The Al(2)-O(12) bond length is 1.73 Å. The Al(2)-O(2) bond length is 1.79 Å. The Al(2)-O(6) bond length is 1.79 Å. In the third Al site, Al(3) is bonded to one O(3), one O(5), one O(8), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. The Al(3)-O(3) bond length is 1.76 Å. The Al(3)-O(5) bond length is 1.85 Å. The Al(3)-O(8) bond length is 1.73 Å. The Al(3)-O(9) bond length is 1.73 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(12), one O(3), one O(6), and one O(9) atom to form SiO4 tetrahedra that share corners with two equivalent Al(2)O4 tetrahedra, corners with two equivalent Al(3)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. The Si(1)-O(12) bond length is 1.62 Å. The Si(1)-O(3) bond length is 1.64 Å. The Si(1)-O(6) bond length is 1.68 Å. The Si(1)-O(9) bond length is 1.61 Å. In the second Si site, Si(2) is bonded to one O(1), one O(10), one O(11), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, corners with two equivalent Al(1)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. The Si(2)-O(1) bond length is 1.63 Å. The Si(2)-O(10) bond length is 1.61 Å. The Si(2)-O(11) bond length is 1.61 Å. The Si(2)-O(5) bond length is 1.72 Å. In the third Si site, Si(3) is bonded to one O(2), one O(4), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, corners with two equivalent Al(1)O4 tetrahedra, and  a cornercorner with one Mg(1)O5 trigonal bipyramid. The Si(3)-O(2) bond length is 1.67 Å. The Si(3)-O(4) bond length is 1.67 Å. The Si(3)-O(7) bond length is 1.61 Å. The Si(3)-O(8) bond length is 1.61 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(1), one Al(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Al(2), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Na(1), one Al(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1), one Al(1), and one Si(3) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mg(1), one Al(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Mg(1), one Al(2), and one Si(1) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(3) and one Si(3) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Al(3) and one Si(1) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(2) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(1) atom. In the thirteenth O site, O(13) is bonded in a single-bond geometry to one Mg(1) atom. In the fourteenth O site, O(14) is bonded in a bent 150 degrees geometry to one Na(1) and one Mg(1) atom. In the fifteenth O site, O(15) is bonded in a distorted single-bond geometry to one Na(1) and one O(16) atom. The O(15)-O(16) bond length is 1.23 Å. In the sixteenth O site, O(16) is bonded in an L-shaped geometry to one Na(1) and one O(15) atom.