KNa2Y(Si2O5)3 crystallizes in the orthorhombic Imma space group. K(1) is bonded in a 10-coordinate geometry to two equivalent O(5), four equivalent O(1), and four equivalent O(4) atoms. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Y(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form YO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Y(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the second Si site, Si(2) is bonded to one O(3), one O(6), and two equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one Y(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 18°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one K(1), one Na(1), one Y(1), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to two equivalent Na(1), one Y(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent Si(1) atoms. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one K(1) and two equivalent Si(1) atoms. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent Si(2) atoms.
KNa2Y(Si2O5)3 crystallizes in the orthorhombic Imma space group. K(1) is bonded in a 10-coordinate geometry to two equivalent O(5), four equivalent O(1), and four equivalent O(4) atoms. Both K(1)-O(5) bond lengths are 3.14 Å. All K(1)-O(1) bond lengths are 3.15 Å. There are two shorter (2.81 Å) and two longer (3.23 Å) K(1)-O(4) bond lengths. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Both Na(1)-O(1) bond lengths are 2.34 Å. Both Na(1)-O(2) bond lengths are 2.57 Å. Both Na(1)-O(3) bond lengths are 2.49 Å. Y(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form YO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. Both Y(1)-O(3) bond lengths are 2.26 Å. All Y(1)-O(1) bond lengths are 2.29 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Y(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. The Si(1)-O(1) bond length is 1.59 Å. The Si(1)-O(2) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.66 Å. The Si(1)-O(5) bond length is 1.67 Å. In the second Si site, Si(2) is bonded to one O(3), one O(6), and two equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one Y(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 18°. The Si(2)-O(3) bond length is 1.60 Å. The Si(2)-O(6) bond length is 1.64 Å. Both Si(2)-O(2) bond lengths are 1.67 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one K(1), one Na(1), one Y(1), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted see-saw-like geometry to two equivalent Na(1), one Y(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent Si(1) atoms. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one K(1) and two equivalent Si(1) atoms. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent Si(2) atoms.