Na2Ca3Si3O10 crystallizes in the monoclinic C2/c space group. Na(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form NaO5 square pyramids that share corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra,  an edgeedge with one Na(1)O5 square pyramid, and  an edgeedge with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-77°. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra, corners with three equivalent Na(1)O5 square pyramids, corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ca(2)O6 octahedra,  an edgeedge with one Na(1)O5 square pyramid, and  an edgeedge with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-69°. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Na(1)O5 square pyramids, and edges with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 67-69°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with six equivalent Na(1)O5 square pyramids, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 53-61°. In the second Si site, Si(2) 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 Ca(2)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Si(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra, and  an edgeedge with one Na(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 52-57°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Ca(2), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Ca(2), and one Si(2) atom. In the third O site, O(3) is bonded to two equivalent Na(1), one Ca(1), and one Si(1) atom to form distorted ONa2CaSi tetrahedra that share  a cornercorner with one O(3)Na2CaSi tetrahedra, corners with two equivalent O(5)Ca3Si trigonal pyramids, and  an edgeedge with one O(3)Na2CaSi tetrahedra. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded to one Ca(2), two equivalent Ca(1), and one Si(2) atom to form distorted OCa3Si trigonal pyramids that share corners with two equivalent O(3)Na2CaSi tetrahedra and corners with three equivalent O(5)Ca3Si trigonal pyramids.
Na2Ca3Si3O10 crystallizes in the monoclinic C2/c space group. Na(1) is bonded to one O(1), one O(2), one O(4), and two equivalent O(3) atoms to form NaO5 square pyramids that share corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra,  an edgeedge with one Na(1)O5 square pyramid, and  an edgeedge with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-77°. The Na(1)-O(1) bond length is 2.41 Å. The Na(1)-O(2) bond length is 2.42 Å. The Na(1)-O(4) bond length is 2.59 Å. There is one shorter (2.35 Å) and one longer (2.36 Å) Na(1)-O(3) bond length. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form distorted CaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra, corners with three equivalent Na(1)O5 square pyramids, corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ca(2)O6 octahedra,  an edgeedge with one Na(1)O5 square pyramid, and  an edgeedge with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-69°. The Ca(1)-O(1) bond length is 2.43 Å. The Ca(1)-O(2) bond length is 2.32 Å. The Ca(1)-O(3) bond length is 2.34 Å. The Ca(1)-O(4) bond length is 2.64 Å. There is one shorter (2.33 Å) and one longer (2.45 Å) Ca(1)-O(5) bond length. In the second Ca site, Ca(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, edges with two equivalent Na(1)O5 square pyramids, and edges with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 67-69°. Both Ca(2)-O(1) bond lengths are 2.33 Å. Both Ca(2)-O(2) bond lengths are 2.45 Å. Both Ca(2)-O(5) bond lengths are 2.39 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with four equivalent Ca(1)O6 octahedra, corners with six equivalent Na(1)O5 square pyramids, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 53-61°. Both Si(1)-O(3) bond lengths are 1.62 Å. Both Si(1)-O(4) bond lengths are 1.70 Å. In the second Si site, Si(2) 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 Ca(2)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra,  a cornercorner with one Na(1)O5 square pyramid,  a cornercorner with one Si(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra,  an edgeedge with one Ca(2)O6 octahedra, and  an edgeedge with one Na(1)O5 square pyramid. The corner-sharing octahedral tilt angles range from 52-57°. The Si(2)-O(1) bond length is 1.62 Å. The Si(2)-O(2) bond length is 1.64 Å. The Si(2)-O(4) bond length is 1.71 Å. The Si(2)-O(5) bond length is 1.65 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Ca(2), and one Si(2) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Ca(2), and one Si(2) atom. In the third O site, O(3) is bonded to two equivalent Na(1), one Ca(1), and one Si(1) atom to form distorted ONa2CaSi tetrahedra that share  a cornercorner with one O(3)Na2CaSi tetrahedra, corners with two equivalent O(5)Ca3Si trigonal pyramids, and  an edgeedge with one O(3)Na2CaSi tetrahedra. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded to one Ca(2), two equivalent Ca(1), and one Si(2) atom to form distorted OCa3Si trigonal pyramids that share corners with two equivalent O(3)Na2CaSi tetrahedra and corners with three equivalent O(5)Ca3Si trigonal pyramids.