Ca3Si4(AgO7)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(4), one O(5), one O(6), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 4-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(7) atoms. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Ag site, Ag(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form AgO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Ag(2)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ag(2)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 70°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ag(2), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ag(1), and one Ag(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(2), one Ag(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Ag(1), one Ag(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Ca(1), one Si(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ca(1), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom.
Ca3Si4(AgO7)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(4), one O(5), one O(6), and two equivalent O(7) atoms. The Ca(1)-O(1) bond length is 2.50 Å. The Ca(1)-O(2) bond length is 2.41 Å. The Ca(1)-O(4) bond length is 2.38 Å. The Ca(1)-O(5) bond length is 2.98 Å. The Ca(1)-O(6) bond length is 2.77 Å. There is one shorter (2.31 Å) and one longer (2.46 Å) Ca(1)-O(7) bond length. In the second Ca site, Ca(2) is bonded in a 4-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(7) atoms. Both Ca(2)-O(1) bond lengths are 2.32 Å. Both Ca(2)-O(3) bond lengths are 2.36 Å. Both Ca(2)-O(7) bond lengths are 2.94 Å. There are two inequivalent Ag sites. In the first Ag site, Ag(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Ag(1)-O(2) bond lengths are 2.00 Å. Both Ag(1)-O(3) bond lengths are 2.10 Å. Both Ag(1)-O(4) bond lengths are 2.70 Å. In the second Ag site, Ag(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form AgO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. Both Ag(2)-O(1) bond lengths are 2.47 Å. Both Ag(2)-O(2) bond lengths are 1.98 Å. Both Ag(2)-O(4) bond lengths are 2.19 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Ag(2)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 47°. The Si(1)-O(4) bond length is 1.63 Å. The Si(1)-O(5) bond length is 1.67 Å. The Si(1)-O(6) bond length is 1.67 Å. The Si(1)-O(7) bond length is 1.61 Å. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Ag(2)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 70°. The Si(2)-O(1) bond length is 1.62 Å. The Si(2)-O(3) bond length is 1.64 Å. The Si(2)-O(5) bond length is 1.67 Å. The Si(2)-O(6) bond length is 1.69 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ag(2), and one Si(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ag(1), and one Ag(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(2), one Ag(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Ag(1), one Ag(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Ca(1), one Si(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ca(1), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom.