Na8Al6Si6O25 crystallizes in the trigonal R3 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a rectangular see-saw-like geometry to one O(3), one O(5), one O(7), and one O(9) atom. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(9) and three equivalent O(4) atoms. In the third Na site, Na(3) is bonded in a trigonal non-coplanar geometry to one O(1), one O(2), and one O(6) atom. In the fourth Na site, Na(4) is bonded in a trigonal planar geometry to three equivalent O(8) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(5), one O(7), and one O(8) atom to form AlO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form AlO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. There are nine inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Na(1), one Al(1), and one Si(2) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Na(3), one Al(2), and one Si(2) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to one Na(1), one Al(1), and one Si(1) atom. In the fourth O site, O(8) is bonded in a 3-coordinate geometry to one Na(4), one Al(1), and one Si(1) atom. In the fifth O site, O(9) is bonded in a tetrahedral geometry to one Na(2) and three equivalent Na(1) atoms. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(3), one Al(2), and one Si(1) atom. In the seventh O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(3), one Al(1), and one Si(2) atom. In the eighth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Al(2), and one Si(1) atom. In the ninth O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Al(2), and one Si(2) atom.
Na8Al6Si6O25 crystallizes in the trigonal R3 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded in a rectangular see-saw-like geometry to one O(3), one O(5), one O(7), and one O(9) atom. The Na(1)-O(3) bond length is 2.59 Å. The Na(1)-O(5) bond length is 2.62 Å. The Na(1)-O(7) bond length is 2.71 Å. The Na(1)-O(9) bond length is 2.28 Å. In the second Na site, Na(2) is bonded in a distorted rectangular see-saw-like geometry to one O(9) and three equivalent O(4) atoms. The Na(2)-O(9) bond length is 2.49 Å. All Na(2)-O(4) bond lengths are 2.63 Å. In the third Na site, Na(3) is bonded in a trigonal non-coplanar geometry to one O(1), one O(2), and one O(6) atom. The Na(3)-O(1) bond length is 2.25 Å. The Na(3)-O(2) bond length is 2.26 Å. The Na(3)-O(6) bond length is 2.24 Å. In the fourth Na site, Na(4) is bonded in a trigonal planar geometry to three equivalent O(8) atoms. All Na(4)-O(8) bond lengths are 2.23 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(5), one O(7), and one O(8) atom to form AlO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. The Al(1)-O(2) bond length is 1.76 Å. The Al(1)-O(5) bond length is 1.76 Å. The Al(1)-O(7) bond length is 1.76 Å. The Al(1)-O(8) bond length is 1.76 Å. In the second Al site, Al(2) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form AlO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. The Al(2)-O(1) bond length is 1.75 Å. The Al(2)-O(3) bond length is 1.75 Å. The Al(2)-O(4) bond length is 1.76 Å. The Al(2)-O(6) bond length is 1.76 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. The Si(1)-O(1) bond length is 1.64 Å. The Si(1)-O(3) bond length is 1.64 Å. The Si(1)-O(7) bond length is 1.64 Å. The Si(1)-O(8) bond length is 1.65 Å. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Al(2)O4 tetrahedra. The Si(2)-O(2) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.64 Å. The Si(2)-O(5) bond length is 1.63 Å. The Si(2)-O(6) bond length is 1.64 Å. There are nine inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Na(1), one Al(1), and one Si(2) atom. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Na(3), one Al(2), and one Si(2) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to one Na(1), one Al(1), and one Si(1) atom. In the fourth O site, O(8) is bonded in a 3-coordinate geometry to one Na(4), one Al(1), and one Si(1) atom. In the fifth O site, O(9) is bonded in a tetrahedral geometry to one Na(2) and three equivalent Na(1) atoms. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Na(3), one Al(2), and one Si(1) atom. In the seventh O site, O(2) is bonded in a distorted trigonal planar geometry to one Na(3), one Al(1), and one Si(2) atom. In the eighth O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Al(2), and one Si(1) atom. In the ninth O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Al(2), and one Si(2) atom.