K2Zn2Si8O19 crystallizes in the monoclinic C2 space group. K(1) is bonded in a 8-coordinate geometry to one O(10), one O(2), one O(3), one O(4), one O(6), one O(9), and two equivalent O(8) atoms. Zn(1) is bonded to one O(3), one O(8), and two equivalent O(10) atoms to form ZnO4 tetrahedra that share  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Zn(1)O4 tetrahedra, and corners with three equivalent Si(2)O4 tetrahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(10), one O(2), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with three equivalent Zn(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(1), one O(6), one O(7), and one O(9) atom to form corner-sharing SiO4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(1), one O(3), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Zn(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. There are ten inequivalent O sites. In the first O site, O(7) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(8) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one Zn(1), and one Si(2) atom. In the third O site, O(9) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(3), and one Si(4) atom. In the fourth O site, O(10) is bonded in a distorted trigonal planar geometry to one K(1), two equivalent Zn(1), and one Si(2) atom. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the sixth O site, O(2) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the seventh O site, O(3) is bonded in a 3-coordinate geometry to one K(1), one Zn(1), and one Si(4) atom. In the eighth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent Si(2) atoms. In the ninth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the tenth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(3) atom.
K2Zn2Si8O19 crystallizes in the monoclinic C2 space group. K(1) is bonded in a 8-coordinate geometry to one O(10), one O(2), one O(3), one O(4), one O(6), one O(9), and two equivalent O(8) atoms. The K(1)-O(10) bond length is 3.13 Å. The K(1)-O(2) bond length is 2.87 Å. The K(1)-O(3) bond length is 2.88 Å. The K(1)-O(4) bond length is 2.88 Å. The K(1)-O(6) bond length is 3.12 Å. The K(1)-O(9) bond length is 2.92 Å. There is one shorter (2.89 Å) and one longer (2.98 Å) K(1)-O(8) bond length. Zn(1) is bonded to one O(3), one O(8), and two equivalent O(10) atoms to form ZnO4 tetrahedra that share  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Zn(1)O4 tetrahedra, and corners with three equivalent Si(2)O4 tetrahedra. The Zn(1)-O(3) bond length is 1.93 Å. The Zn(1)-O(8) bond length is 1.95 Å. There is one shorter (2.02 Å) and one longer (2.04 Å) Zn(1)-O(10) bond length. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), one O(6), and one O(7) atom to form corner-sharing SiO4 tetrahedra. The Si(1)-O(2) bond length is 1.63 Å. The Si(1)-O(5) bond length is 1.62 Å. The Si(1)-O(6) bond length is 1.63 Å. The Si(1)-O(7) bond length is 1.63 Å. In the second Si site, Si(2) is bonded to one O(10), one O(2), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and corners with three equivalent Zn(1)O4 tetrahedra. The Si(2)-O(10) bond length is 1.64 Å. The Si(2)-O(2) bond length is 1.66 Å. The Si(2)-O(4) bond length is 1.66 Å. The Si(2)-O(8) bond length is 1.61 Å. In the third Si site, Si(3) is bonded to one O(1), one O(6), one O(7), and one O(9) atom to form corner-sharing SiO4 tetrahedra. The Si(3)-O(1) bond length is 1.62 Å. The Si(3)-O(6) bond length is 1.63 Å. The Si(3)-O(7) bond length is 1.63 Å. The Si(3)-O(9) bond length is 1.63 Å. In the fourth Si site, Si(4) is bonded to one O(1), one O(3), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Zn(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(3)O4 tetrahedra. The Si(4)-O(1) bond length is 1.65 Å. The Si(4)-O(3) bond length is 1.60 Å. The Si(4)-O(5) bond length is 1.64 Å. The Si(4)-O(9) bond length is 1.65 Å. There are ten inequivalent O sites. In the first O site, O(7) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(8) is bonded in a distorted bent 120 degrees geometry to two equivalent K(1), one Zn(1), and one Si(2) atom. In the third O site, O(9) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(3), and one Si(4) atom. In the fourth O site, O(10) is bonded in a distorted trigonal planar geometry to one K(1), two equivalent Zn(1), and one Si(2) atom. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the sixth O site, O(2) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(2) atom. In the seventh O site, O(3) is bonded in a 3-coordinate geometry to one K(1), one Zn(1), and one Si(4) atom. In the eighth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent Si(2) atoms. In the ninth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the tenth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one K(1), one Si(1), and one Si(3) atom.