TlAlSiO4 crystallizes in the trigonal R3c space group. Tl(1) is bonded in a distorted T-shaped geometry to one O(2), one O(3), and one O(4) atom. Al(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share corners with four equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Al(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Tl(1), one Al(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Tl(1), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Tl(1), one Al(1), and one Si(1) atom.
TlAlSiO4 crystallizes in the trigonal R3c space group. Tl(1) is bonded in a distorted T-shaped geometry to one O(2), one O(3), and one O(4) atom. The Tl(1)-O(2) bond length is 2.69 Å. The Tl(1)-O(3) bond length is 2.69 Å. The Tl(1)-O(4) bond length is 2.64 Å. Al(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share corners with four equivalent Si(1)O4 tetrahedra. The Al(1)-O(1) bond length is 1.74 Å. The Al(1)-O(2) bond length is 1.77 Å. The Al(1)-O(3) bond length is 1.77 Å. The Al(1)-O(4) bond length is 1.77 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with four equivalent Al(1)O4 tetrahedra. The Si(1)-O(1) bond length is 1.62 Å. The Si(1)-O(2) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.64 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Tl(1), one Al(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Tl(1), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Tl(1), one Al(1), and one Si(1) atom.