CaAl2Si3O10 crystallizes in the triclinic P1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(10), one O(15), one O(5), one O(6), one O(8), and one O(9) atom to form distorted CaO6 octahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra, and  an edgeedge with one Si(4)O4 tetrahedra. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(10), one O(16), one O(3), one O(5), one O(6), one O(7), and one O(9) atom. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(11), one O(14), and one O(17) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(12), one O(13), one O(18), and one O(2) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. In the third Al site, Al(3) is bonded to one O(19), one O(2), one O(3), and one O(9) atom to form distorted AlO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. In the fourth Al site, Al(4) is bonded to one O(1), one O(10), one O(20), and one O(4) atom to form AlO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 70°. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(10), one O(12), and one O(3) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, and  an edgeedge with one Al(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 32°. In the second Si site, Si(2) is bonded to one O(11), one O(2), one O(4), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  an edgeedge with one Al(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. In the third Si site, Si(3) is bonded to one O(15), one O(18), one O(5), and one O(7) atom to form distorted SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one Si(5)O4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(16), one O(17), one O(6), and one O(8) atom to form distorted SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one Si(6)O4 tetrahedra. In the fifth Si site, Si(5) is bonded to one O(13), one O(15), one O(20), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  an edgeedge with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the sixth Si site, Si(6) is bonded to one O(14), one O(16), one O(19), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, and  an edgeedge with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. There are twenty inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Al(1), one Al(4), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Al(2), one Al(3), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ca(2), one Al(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(4) and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Si(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Si(4) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ca(2), one Si(3), and one Si(5) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ca(1), one Si(4), and one Si(6) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(3), and one Si(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(4), and one Si(1) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one Al(1) and one Si(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(1) atom. In the thirteenth O site, O(13) is bonded in a bent 120 degrees geometry to one Al(2) and one Si(5) atom. In the fourteenth O site, O(14) is bonded in a bent 120 degrees geometry to one Al(1) and one Si(6) atom. In the fifteenth O site, O(15) is bonded in a distorted T-shaped geometry to one Ca(1), one Si(3), and one Si(5) atom. In the sixteenth O site, O(16) is bonded in a distorted T-shaped geometry to one Ca(2), one Si(4), and one Si(6) atom. In the seventeenth O site, O(17) is bonded in a bent 120 degrees geometry to one Al(1) and one Si(4) atom. In the eighteenth O site, O(18) is bonded in a bent 120 degrees geometry to one Al(2) and one Si(3) atom. In the nineteenth O site, O(19) is bonded in a bent 120 degrees geometry to one Al(3) and one Si(6) atom. In the twentieth O site, O(20) is bonded in a bent 120 degrees geometry to one Al(4) and one Si(5) atom.
CaAl2Si3O10 crystallizes in the triclinic P1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(10), one O(15), one O(5), one O(6), one O(8), and one O(9) atom to form distorted CaO6 octahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra,  an edgeedge with one Si(3)O4 tetrahedra, and  an edgeedge with one Si(4)O4 tetrahedra. The Ca(1)-O(10) bond length is 2.52 Å. The Ca(1)-O(15) bond length is 2.43 Å. The Ca(1)-O(5) bond length is 2.46 Å. The Ca(1)-O(6) bond length is 2.43 Å. The Ca(1)-O(8) bond length is 2.42 Å. The Ca(1)-O(9) bond length is 2.59 Å. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(10), one O(16), one O(3), one O(5), one O(6), one O(7), and one O(9) atom. The Ca(2)-O(10) bond length is 2.87 Å. The Ca(2)-O(16) bond length is 2.37 Å. The Ca(2)-O(3) bond length is 2.88 Å. The Ca(2)-O(5) bond length is 2.41 Å. The Ca(2)-O(6) bond length is 2.49 Å. The Ca(2)-O(7) bond length is 2.38 Å. The Ca(2)-O(9) bond length is 2.79 Å. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(11), one O(14), and one O(17) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Si(6)O4 tetrahedra. The Al(1)-O(1) bond length is 1.81 Å. The Al(1)-O(11) bond length is 1.71 Å. The Al(1)-O(14) bond length is 1.77 Å. The Al(1)-O(17) bond length is 1.79 Å. In the second Al site, Al(2) is bonded to one O(12), one O(13), one O(18), and one O(2) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Si(5)O4 tetrahedra. The Al(2)-O(12) bond length is 1.73 Å. The Al(2)-O(13) bond length is 1.78 Å. The Al(2)-O(18) bond length is 1.79 Å. The Al(2)-O(2) bond length is 1.83 Å. In the third Al site, Al(3) is bonded to one O(19), one O(2), one O(3), and one O(9) atom to form distorted AlO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. The Al(3)-O(19) bond length is 1.73 Å. The Al(3)-O(2) bond length is 1.84 Å. The Al(3)-O(3) bond length is 1.74 Å. The Al(3)-O(9) bond length is 1.87 Å. In the fourth Al site, Al(4) is bonded to one O(1), one O(10), one O(20), and one O(4) atom to form AlO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(5)O4 tetrahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 70°. The Al(4)-O(1) bond length is 1.82 Å. The Al(4)-O(10) bond length is 1.86 Å. The Al(4)-O(20) bond length is 1.72 Å. The Al(4)-O(4) bond length is 1.71 Å. There are six inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(10), one O(12), and one O(3) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, and  an edgeedge with one Al(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 32°. The Si(1)-O(1) bond length is 1.73 Å. The Si(1)-O(10) bond length is 1.69 Å. The Si(1)-O(12) bond length is 1.58 Å. The Si(1)-O(3) bond length is 1.61 Å. In the second Si site, Si(2) is bonded to one O(11), one O(2), one O(4), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  an edgeedge with one Al(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. The Si(2)-O(11) bond length is 1.58 Å. The Si(2)-O(2) bond length is 1.74 Å. The Si(2)-O(4) bond length is 1.59 Å. The Si(2)-O(9) bond length is 1.70 Å. In the third Si site, Si(3) is bonded to one O(15), one O(18), one O(5), and one O(7) atom to form distorted SiO4 tetrahedra that share  a cornercorner with one Al(2)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one Si(5)O4 tetrahedra. The Si(3)-O(15) bond length is 1.73 Å. The Si(3)-O(18) bond length is 1.61 Å. The Si(3)-O(5) bond length is 1.60 Å. The Si(3)-O(7) bond length is 1.75 Å. In the fourth Si site, Si(4) is bonded to one O(16), one O(17), one O(6), and one O(8) atom to form distorted SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and  an edgeedge with one Si(6)O4 tetrahedra. The Si(4)-O(16) bond length is 1.74 Å. The Si(4)-O(17) bond length is 1.61 Å. The Si(4)-O(6) bond length is 1.59 Å. The Si(4)-O(8) bond length is 1.74 Å. In the fifth Si site, Si(5) is bonded to one O(13), one O(15), one O(20), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(4)O4 tetrahedra, and  an edgeedge with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. The Si(5)-O(13) bond length is 1.60 Å. The Si(5)-O(15) bond length is 1.73 Å. The Si(5)-O(20) bond length is 1.60 Å. The Si(5)-O(7) bond length is 1.72 Å. In the sixth Si site, Si(6) is bonded to one O(14), one O(16), one O(19), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, and  an edgeedge with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 45°. The Si(6)-O(14) bond length is 1.60 Å. The Si(6)-O(16) bond length is 1.73 Å. The Si(6)-O(19) bond length is 1.60 Å. The Si(6)-O(8) bond length is 1.72 Å. There are twenty inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Al(1), one Al(4), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Al(2), one Al(3), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ca(2), one Al(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(4) and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Si(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Si(4) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ca(2), one Si(3), and one Si(5) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ca(1), one Si(4), and one Si(6) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(3), and one Si(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(4), and one Si(1) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one Al(1) and one Si(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(1) atom. In the thirteenth O site, O(13) is bonded in a bent 120 degrees geometry to one Al(2) and one Si(5) atom. In the fourteenth O site, O(14) is bonded in a bent 120 degrees geometry to one Al(1) and one Si(6) atom. In the fifteenth O site, O(15) is bonded in a distorted T-shaped geometry to one Ca(1), one Si(3), and one Si(5) atom. In the sixteenth O site, O(16) is bonded in a distorted T-shaped geometry to one Ca(2), one Si(4), and one Si(6) atom. In the seventeenth O site, O(17) is bonded in a bent 120 degrees geometry to one Al(1) and one Si(4) atom. In the eighteenth O site, O(18) is bonded in a bent 120 degrees geometry to one Al(2) and one Si(3) atom. In the nineteenth O site, O(19) is bonded in a bent 120 degrees geometry to one Al(3) and one Si(6) atom. In the twentieth O site, O(20) is bonded in a bent 120 degrees geometry to one Al(4) and one Si(5) atom.