Ca2MnAl2Si3O13 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 6-coordinate geometry to one O(2), one O(9), two equivalent O(1), and two equivalent O(5) atoms. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(10), one O(2), two equivalent O(5), and four equivalent O(4) atoms. Mn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(9) atoms to form MnO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and edges with two equivalent Mn(1)O6 octahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(10), two equivalent O(5), and two equivalent O(7) atoms to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Al(1)O6 octahedra. In the second Al site, Al(2) is bonded in a distorted see-saw-like geometry to one O(3), one O(6), and two equivalent O(4) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(7), one O(9), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and corners with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-51°. In the second Si site, Si(2) is bonded to one O(6), one O(8), and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. In the third Si site, Si(3) is bonded to one O(2), one O(8), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. There are ten inequivalent O sites. In the first O site, O(6) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the second O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Al(1) and one Si(1) atom. In the third O site, O(8) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the fourth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Mn(1), and one Si(1) atom. In the fifth O site, O(10) is bonded in a trigonal non-coplanar geometry to one Ca(2) and two equivalent Al(1) atoms. In the sixth O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Si(3) atom. In the seventh O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Si(3) atom. In the eighth O site, O(3) is bonded in a trigonal non-coplanar geometry to two equivalent Mn(1) and one Al(2) atom. In the ninth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Ca(2), one Al(2), and one Si(1) atom. In the tenth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(1), and one Si(2) atom.
Ca2MnAl2Si3O13 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 6-coordinate geometry to one O(2), one O(9), two equivalent O(1), and two equivalent O(5) atoms. The Ca(1)-O(2) bond length is 2.31 Å. The Ca(1)-O(9) bond length is 2.55 Å. Both Ca(1)-O(1) bond lengths are 2.52 Å. Both Ca(1)-O(5) bond lengths are 2.34 Å. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(10), one O(2), two equivalent O(5), and four equivalent O(4) atoms. The Ca(2)-O(10) bond length is 2.30 Å. The Ca(2)-O(2) bond length is 2.27 Å. Both Ca(2)-O(5) bond lengths are 2.59 Å. There are two shorter (2.71 Å) and two longer (2.91 Å) Ca(2)-O(4) bond lengths. Mn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(9) atoms to form MnO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and edges with two equivalent Mn(1)O6 octahedra. Both Mn(1)-O(1) bond lengths are 1.95 Å. Both Mn(1)-O(3) bond lengths are 1.91 Å. Both Mn(1)-O(9) bond lengths are 2.05 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(10), two equivalent O(5), and two equivalent O(7) atoms to form AlO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Al(1)O6 octahedra. Both Al(1)-O(10) bond lengths are 1.84 Å. Both Al(1)-O(5) bond lengths are 1.91 Å. Both Al(1)-O(7) bond lengths are 2.03 Å. In the second Al site, Al(2) is bonded in a distorted see-saw-like geometry to one O(3), one O(6), and two equivalent O(4) atoms. The Al(2)-O(3) bond length is 1.85 Å. The Al(2)-O(6) bond length is 1.76 Å. Both Al(2)-O(4) bond lengths are 1.85 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(7), one O(9), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and corners with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-51°. The Si(1)-O(7) bond length is 1.64 Å. The Si(1)-O(9) bond length is 1.71 Å. Both Si(1)-O(4) bond lengths are 1.65 Å. In the second Si site, Si(2) is bonded to one O(6), one O(8), and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. The Si(2)-O(6) bond length is 1.62 Å. The Si(2)-O(8) bond length is 1.66 Å. Both Si(2)-O(5) bond lengths are 1.64 Å. In the third Si site, Si(3) is bonded to one O(2), one O(8), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. The Si(3)-O(2) bond length is 1.59 Å. The Si(3)-O(8) bond length is 1.65 Å. Both Si(3)-O(1) bond lengths are 1.66 Å. There are ten inequivalent O sites. In the first O site, O(6) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the second O site, O(7) is bonded in a 3-coordinate geometry to two equivalent Al(1) and one Si(1) atom. In the third O site, O(8) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(3) atom. In the fourth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Mn(1), and one Si(1) atom. In the fifth O site, O(10) is bonded in a trigonal non-coplanar geometry to one Ca(2) and two equivalent Al(1) atoms. In the sixth O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Mn(1), and one Si(3) atom. In the seventh O site, O(2) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Si(3) atom. In the eighth O site, O(3) is bonded in a trigonal non-coplanar geometry to two equivalent Mn(1) and one Al(2) atom. In the ninth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent Ca(2), one Al(2), and one Si(1) atom. In the tenth O site, O(5) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(1), and one Si(2) atom.