KAlSi2O6 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms. Al(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. In the second Si site, Si(2) is bonded to two equivalent O(1) and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to two equivalent O(2) and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(2), one Al(1), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1), one Si(1), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to one K(2), one Al(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one K(1), one K(2), one Al(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one K(1), one K(2), one Si(1), and one Si(2) atom.
KAlSi2O6 crystallizes in the orthorhombic C222_1 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. Both K(1)-O(2) bond lengths are 2.99 Å. Both K(1)-O(3) bond lengths are 3.02 Å. Both K(1)-O(5) bond lengths are 2.63 Å. Both K(1)-O(6) bond lengths are 3.12 Å. In the second K site, K(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms. Both K(2)-O(1) bond lengths are 2.85 Å. Both K(2)-O(4) bond lengths are 3.05 Å. Both K(2)-O(5) bond lengths are 3.09 Å. Both K(2)-O(6) bond lengths are 2.69 Å. Al(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The Al(1)-O(1) bond length is 1.76 Å. The Al(1)-O(3) bond length is 1.76 Å. The Al(1)-O(4) bond length is 1.75 Å. The Al(1)-O(5) bond length is 1.77 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. The Si(1)-O(2) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.61 Å. The Si(1)-O(4) bond length is 1.62 Å. The Si(1)-O(6) bond length is 1.66 Å. In the second Si site, Si(2) is bonded to two equivalent O(1) and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. Both Si(2)-O(1) bond lengths are 1.62 Å. Both Si(2)-O(6) bond lengths are 1.65 Å. In the third Si site, Si(3) is bonded to two equivalent O(2) and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. Both Si(3)-O(2) bond lengths are 1.66 Å. Both Si(3)-O(5) bond lengths are 1.62 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one K(2), one Al(1), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one K(1), one Si(1), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to one K(2), one Al(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one K(1), one K(2), one Al(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one K(1), one K(2), one Si(1), and one Si(2) atom.