Ca2Th(Si2O5)4 crystallizes in the tetragonal I422 space group. Ca(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(3) atoms. Th(1) is bonded in a 8-coordinate geometry to eight equivalent O(1) atoms. Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form corner-sharing SiO4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Th(1), and one Si(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and two equivalent Si(1) atoms.
Ca2Th(Si2O5)4 crystallizes in the tetragonal I422 space group. Ca(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(3) atoms. All Ca(1)-O(1) bond lengths are 2.35 Å. All Ca(1)-O(3) bond lengths are 2.73 Å. Th(1) is bonded in a 8-coordinate geometry to eight equivalent O(1) atoms. All Th(1)-O(1) bond lengths are 2.42 Å. Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.60 Å. The Si(1)-O(2) bond length is 1.62 Å. There is one shorter (1.65 Å) and one longer (1.66 Å) Si(1)-O(3) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Th(1), and one Si(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and two equivalent Si(1) atoms.