Ca2SiO4 crystallizes in the monoclinic Cc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. In the second Ca site, Ca(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. Si(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Ca(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Si(1) atom.
Ca2SiO4 crystallizes in the monoclinic Cc space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. The Ca(1)-O(3) bond length is 2.34 Å. The Ca(1)-O(4) bond length is 2.43 Å. There is one shorter (2.24 Å) and one longer (2.41 Å) Ca(1)-O(1) bond length. There is one shorter (2.53 Å) and one longer (2.76 Å) Ca(1)-O(2) bond length. In the second Ca site, Ca(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(3) atoms. The Ca(2)-O(1) bond length is 2.46 Å. The Ca(2)-O(2) bond length is 2.36 Å. The Ca(2)-O(4) bond length is 2.23 Å. There is one shorter (2.42 Å) and one longer (2.53 Å) Ca(2)-O(3) bond length. Si(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Si(1)-O(1) bond length is 1.64 Å. The Si(1)-O(2) bond length is 1.64 Å. The Si(1)-O(3) bond length is 1.70 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 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Ca(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Si(1) atom.