Ca2FeAl2Si3O13 crystallizes in the monoclinic P2_1/m 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(10), two equivalent O(4), two equivalent O(5), and two equivalent O(8) atoms. In the second Ca site, Ca(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Ca(2)O6 pentagonal pyramids, corners with two equivalent Al(2)O4 tetrahedra, corners with two equivalent Al(1)O4 trigonal pyramids, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with two equivalent Ca(2)O6 pentagonal pyramids, corners with two equivalent Si(2)O4 trigonal pyramids, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Al(1)O4 trigonal pyramids. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), one O(6), and two equivalent O(5) atoms to form AlO4 trigonal pyramids that share corners with two equivalent Ca(2)O6 pentagonal pyramids,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(2)O4 trigonal pyramid, and edges with two equivalent Fe(1)O6 octahedra. In the second Al site, Al(2) is bonded to one O(10), one O(9), and two equivalent O(7) atoms to form AlO4 tetrahedra that share corners with two equivalent Ca(2)O6 pentagonal pyramids,  a cornercorner with one Si(3)O4 tetrahedra, and corners with three equivalent Si(1)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(9), and two equivalent O(7) atoms to form SiO4 tetrahedra that share corners with three equivalent Al(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 trigonal pyramid, and  an edgeedge with one Ca(2)O6 pentagonal pyramid. In the second Si site, Si(2) is bonded to one O(1), one O(3), and two equivalent O(8) atoms to form distorted SiO4 trigonal pyramids that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and  a cornercorner with one Al(1)O4 trigonal pyramid. The corner-sharing octahedral tilt angles are 56°. In the third Si site, Si(3) is bonded to one O(10), one O(6), and two equivalent O(8) atoms to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(1)O4 trigonal pyramid, and corners with two equivalent Si(2)O4 trigonal pyramids. There are ten inequivalent O sites. In the first O site, O(8) is bonded in a 3-coordinate geometry to one Ca(1), one Si(2), and one Si(3) atom. In the second O site, O(9) is bonded in a bent 120 degrees geometry to one Al(2) and one Si(1) atom. In the third O site, O(10) is bonded in a distorted water-like geometry to one Ca(1), one Al(2), and one Si(3) atom. In the fourth O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the fifth O site, O(2) is bonded in a water-like geometry to two equivalent Fe(1) atoms. In the sixth O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Fe(1), one Al(1), and one Si(2) atom. In the seventh O site, O(4) is bonded in a square co-planar geometry to two equivalent Ca(1) and two equivalent Ca(2) atoms. In the eighth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Fe(1), and one Al(1) atom. In the ninth O site, O(6) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(3) atom. In the tenth O site, O(7) is bonded in a 3-coordinate geometry to one Ca(2), one Al(2), and one Si(1) atom.
Ca2FeAl2Si3O13 crystallizes in the monoclinic P2_1/m 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(10), two equivalent O(4), two equivalent O(5), and two equivalent O(8) atoms. The Ca(1)-O(10) bond length is 2.85 Å. Both Ca(1)-O(4) bond lengths are 2.30 Å. Both Ca(1)-O(5) bond lengths are 2.60 Å. Both Ca(1)-O(8) bond lengths are 2.66 Å. In the second Ca site, Ca(2) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Ca(2)O6 pentagonal pyramids, corners with two equivalent Al(2)O4 tetrahedra, corners with two equivalent Al(1)O4 trigonal pyramids, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. Both Ca(2)-O(4) bond lengths are 2.32 Å. Both Ca(2)-O(5) bond lengths are 2.40 Å. Both Ca(2)-O(7) bond lengths are 2.42 Å. Fe(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with two equivalent Ca(2)O6 pentagonal pyramids, corners with two equivalent Si(2)O4 trigonal pyramids, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Al(1)O4 trigonal pyramids. Both Fe(1)-O(2) bond lengths are 1.80 Å. Both Fe(1)-O(3) bond lengths are 2.31 Å. Both Fe(1)-O(5) bond lengths are 2.01 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), one O(6), and two equivalent O(5) atoms to form AlO4 trigonal pyramids that share corners with two equivalent Ca(2)O6 pentagonal pyramids,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(2)O4 trigonal pyramid, and edges with two equivalent Fe(1)O6 octahedra. The Al(1)-O(3) bond length is 1.83 Å. The Al(1)-O(6) bond length is 1.80 Å. Both Al(1)-O(5) bond lengths are 1.81 Å. In the second Al site, Al(2) is bonded to one O(10), one O(9), and two equivalent O(7) atoms to form AlO4 tetrahedra that share corners with two equivalent Ca(2)O6 pentagonal pyramids,  a cornercorner with one Si(3)O4 tetrahedra, and corners with three equivalent Si(1)O4 tetrahedra. The Al(2)-O(10) bond length is 1.76 Å. The Al(2)-O(9) bond length is 1.73 Å. Both Al(2)-O(7) bond lengths are 1.82 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(9), and two equivalent O(7) atoms to form SiO4 tetrahedra that share corners with three equivalent Al(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 trigonal pyramid, and  an edgeedge with one Ca(2)O6 pentagonal pyramid. The Si(1)-O(1) bond length is 1.68 Å. The Si(1)-O(9) bond length is 1.61 Å. Both Si(1)-O(7) bond lengths are 1.67 Å. In the second Si site, Si(2) is bonded to one O(1), one O(3), and two equivalent O(8) atoms to form distorted SiO4 trigonal pyramids that share corners with two equivalent Fe(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and  a cornercorner with one Al(1)O4 trigonal pyramid. The corner-sharing octahedral tilt angles are 56°. The Si(2)-O(1) bond length is 1.66 Å. The Si(2)-O(3) bond length is 1.66 Å. Both Si(2)-O(8) bond lengths are 1.68 Å. In the third Si site, Si(3) is bonded to one O(10), one O(6), and two equivalent O(8) atoms to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(1)O4 trigonal pyramid, and corners with two equivalent Si(2)O4 trigonal pyramids. The Si(3)-O(10) bond length is 1.62 Å. The Si(3)-O(6) bond length is 1.62 Å. Both Si(3)-O(8) bond lengths are 1.69 Å. There are ten inequivalent O sites. In the first O site, O(8) is bonded in a 3-coordinate geometry to one Ca(1), one Si(2), and one Si(3) atom. In the second O site, O(9) is bonded in a bent 120 degrees geometry to one Al(2) and one Si(1) atom. In the third O site, O(10) is bonded in a distorted water-like geometry to one Ca(1), one Al(2), and one Si(3) atom. In the fourth O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the fifth O site, O(2) is bonded in a water-like geometry to two equivalent Fe(1) atoms. In the sixth O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Fe(1), one Al(1), and one Si(2) atom. In the seventh O site, O(4) is bonded in a square co-planar geometry to two equivalent Ca(1) and two equivalent Ca(2) atoms. In the eighth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Fe(1), and one Al(1) atom. In the ninth O site, O(6) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(3) atom. In the tenth O site, O(7) is bonded in a 3-coordinate geometry to one Ca(2), one Al(2), and one Si(1) atom.