K4SiO4 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent K sites. In the first K site, K(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form distorted KO4 tetrahedra that share corners with four equivalent Si(1)O4 tetrahedra and  an edgeedge with one K(1)O4 tetrahedra. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(4), two equivalent O(2), and three equivalent O(1) atoms. In the third K site, K(3) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), and two equivalent O(1) atoms. In the fourth K site, K(4) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(3), and two equivalent O(4) atoms. 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 K(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent K(3), three equivalent K(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one K(1), one K(3), one K(4), two equivalent K(2), and one Si(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one K(3), two equivalent K(1), two equivalent K(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one K(1), one K(2), one K(3), two equivalent K(4), and one Si(1) atom.
K4SiO4 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent K sites. In the first K site, K(1) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form distorted KO4 tetrahedra that share corners with four equivalent Si(1)O4 tetrahedra and  an edgeedge with one K(1)O4 tetrahedra. The K(1)-O(2) bond length is 2.56 Å. The K(1)-O(4) bond length is 2.65 Å. There is one shorter (2.59 Å) and one longer (2.63 Å) K(1)-O(3) bond length. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(4), two equivalent O(2), and three equivalent O(1) atoms. The K(2)-O(4) bond length is 2.89 Å. There is one shorter (2.86 Å) and one longer (3.14 Å) K(2)-O(2) bond length. There are a spread of K(2)-O(1) bond distances ranging from 2.65-2.92 Å. In the third K site, K(3) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(4), and two equivalent O(1) atoms. The K(3)-O(2) bond length is 2.64 Å. The K(3)-O(3) bond length is 3.02 Å. The K(3)-O(4) bond length is 2.71 Å. There is one shorter (2.60 Å) and one longer (2.65 Å) K(3)-O(1) bond length. In the fourth K site, K(4) is bonded in a 5-coordinate geometry to one O(2), two equivalent O(3), and two equivalent O(4) atoms. The K(4)-O(2) bond length is 2.66 Å. There is one shorter (2.72 Å) and one longer (2.76 Å) K(4)-O(3) bond length. There is one shorter (2.77 Å) and one longer (2.82 Å) K(4)-O(4) bond length. 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 K(1)O4 tetrahedra. The Si(1)-O(1) bond length is 1.65 Å. The Si(1)-O(2) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.66 Å. The Si(1)-O(4) bond length is 1.66 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent K(3), three equivalent K(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one K(1), one K(3), one K(4), two equivalent K(2), and one Si(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one K(3), two equivalent K(1), two equivalent K(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to one K(1), one K(2), one K(3), two equivalent K(4), and one Si(1) atom.