Na4SiO4 crystallizes in the triclinic P-1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share corners with three equivalent Na(2)O5 square pyramids, corners with two equivalent Na(4)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, edges with three equivalent Na(2)O5 square pyramids,  an edgeedge with one Si(1)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. In the second Na site, Na(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Na(4)O4 tetrahedra, corners with three equivalent Na(1)O5 trigonal bipyramids, edges with two equivalent Na(2)O5 square pyramids, edges with two equivalent Si(1)O4 tetrahedra, and edges with three equivalent Na(1)O5 trigonal bipyramids. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. In the fourth Na site, Na(4) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted NaO4 tetrahedra that share corners with two equivalent Na(2)O5 square pyramids, corners with four equivalent Si(1)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids, and edges with two equivalent Na(4)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  a cornercorner with one Na(2)O5 square pyramid, corners with four equivalent Na(4)O4 tetrahedra, corners with three equivalent Na(1)O5 trigonal bipyramids, edges with two equivalent Na(2)O5 square pyramids, and  an edgeedge with one Na(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Si(1) atom. In the second O site, O(2) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Si(1) atom to form a mixture of distorted edge and corner-sharing ONa5Si octahedra. The corner-sharing octahedral tilt angles range from 17-19°. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Na(3), two equivalent Na(4), and one Si(1) atom to form a mixture of distorted edge and corner-sharing ONa5Si octahedra. The corner-sharing octahedral tilt angles range from 17-19°. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(3), two equivalent Na(4), and one Si(1) atom.
Na4SiO4 crystallizes in the triclinic P-1 space group. There are four inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share corners with three equivalent Na(2)O5 square pyramids, corners with two equivalent Na(4)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, edges with three equivalent Na(2)O5 square pyramids,  an edgeedge with one Si(1)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. The Na(1)-O(3) bond length is 2.43 Å. There is one shorter (2.33 Å) and one longer (2.41 Å) Na(1)-O(1) bond length. There is one shorter (2.30 Å) and one longer (2.33 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted NaO5 square pyramids that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Na(4)O4 tetrahedra, corners with three equivalent Na(1)O5 trigonal bipyramids, edges with two equivalent Na(2)O5 square pyramids, edges with two equivalent Si(1)O4 tetrahedra, and edges with three equivalent Na(1)O5 trigonal bipyramids. The Na(2)-O(3) bond length is 2.32 Å. There is one shorter (2.42 Å) and one longer (2.44 Å) Na(2)-O(1) bond length. There is one shorter (2.32 Å) and one longer (2.34 Å) Na(2)-O(2) bond length. In the third Na site, Na(3) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Na(3)-O(1) bond length is 2.36 Å. The Na(3)-O(2) bond length is 2.35 Å. The Na(3)-O(3) bond length is 2.38 Å. The Na(3)-O(4) bond length is 2.31 Å. In the fourth Na site, Na(4) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form distorted NaO4 tetrahedra that share corners with two equivalent Na(2)O5 square pyramids, corners with four equivalent Si(1)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids, and edges with two equivalent Na(4)O4 tetrahedra. Both Na(4)-O(3) bond lengths are 2.29 Å. There is one shorter (2.25 Å) and one longer (2.29 Å) Na(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  a cornercorner with one Na(2)O5 square pyramid, corners with four equivalent Na(4)O4 tetrahedra, corners with three equivalent Na(1)O5 trigonal bipyramids, edges with two equivalent Na(2)O5 square pyramids, and  an edgeedge with one Na(1)O5 trigonal bipyramid. The Si(1)-O(1) bond length is 1.65 Å. The Si(1)-O(2) bond length is 1.66 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 6-coordinate geometry to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Si(1) atom. In the second O site, O(2) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Si(1) atom to form a mixture of distorted edge and corner-sharing ONa5Si octahedra. The corner-sharing octahedral tilt angles range from 17-19°. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Na(3), two equivalent Na(4), and one Si(1) atom to form a mixture of distorted edge and corner-sharing ONa5Si octahedra. The corner-sharing octahedral tilt angles range from 17-19°. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(3), two equivalent Na(4), and one Si(1) atom.