CaAl2Si3O10 crystallizes in the triclinic P1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 4-coordinate geometry to one O(10), one O(16), one O(6), and one O(9) atom. In the second Ca site, Ca(2) is bonded in a 3-coordinate geometry to one O(10), one O(5), 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 Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra, and  a cornercorner with one Al(4)O4 trigonal pyramid. 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 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. 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 distorted AlO4 trigonal pyramids that share  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. 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 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 trigonal pyramid. 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 Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(4)O4 trigonal pyramid, and  an edgeedge with one Al(3)O4 tetrahedra. 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 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 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 Al(2)O4 tetrahedra,  a cornercorner with one Al(4)O4 trigonal pyramid, and  an edgeedge with one Si(3)O4 tetrahedra. 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 Al(1)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, and  an edgeedge with one Si(4)O4 tetrahedra. 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 bent 150 degrees geometry to 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 water-like geometry to one Ca(2) and one Si(3) atom. In the sixth O site, O(6) is bonded in a water-like geometry to one Ca(1) and one Si(4) atom. In the seventh O site, O(7) is bonded in an L-shaped geometry to one Si(3) and one Si(5) atom. In the eighth O site, O(8) is bonded in an L-shaped geometry to one Si(4) and one Si(6) atom. In the ninth O site, O(9) is bonded to one Ca(1), one Ca(2), one Al(3), and one Si(2) atom to form distorted corner-sharing OCa2AlSi tetrahedra. In the tenth O site, O(10) is bonded to one Ca(1), one Ca(2), one Al(4), and one Si(1) atom to form distorted corner-sharing OCa2AlSi tetrahedra. In the eleventh O site, O(11) is bonded in a bent 150 degrees 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 water-like geometry to one Al(2) and one Si(5) atom. In the fourteenth O site, O(14) is bonded in a water-like geometry to one Al(1) and one Si(6) atom. In the fifteenth O site, O(15) is bonded in a distorted L-shaped geometry to one Si(3) and one Si(5) atom. In the sixteenth O site, O(16) is bonded in a distorted L-shaped geometry to one Ca(1), 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 in a 4-coordinate geometry to one O(10), one O(16), one O(6), and one O(9) atom. The Ca(1)-O(10) bond length is 2.52 Å. The Ca(1)-O(16) bond length is 2.91 Å. The Ca(1)-O(6) bond length is 2.13 Å. The Ca(1)-O(9) bond length is 2.55 Å. In the second Ca site, Ca(2) is bonded in a 3-coordinate geometry to one O(10), one O(5), and one O(9) atom. The Ca(2)-O(10) bond length is 2.56 Å. The Ca(2)-O(5) bond length is 2.13 Å. The Ca(2)-O(9) bond length is 2.47 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 Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra,  a cornercorner with one Si(6)O4 tetrahedra, and  a cornercorner with one Al(4)O4 trigonal pyramid. The Al(1)-O(1) bond length is 1.83 Å. The Al(1)-O(11) bond length is 1.74 Å. The Al(1)-O(14) bond length is 1.76 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 1.74 Å. The Al(2)-O(13) bond length is 1.76 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 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 Al(3)-O(19) bond length is 1.72 Å. The Al(3)-O(2) bond length is 1.85 Å. The Al(3)-O(3) bond length is 1.72 Å. The Al(3)-O(9) bond length is 1.94 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 distorted AlO4 trigonal pyramids that share  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 Al(4)-O(1) bond length is 1.84 Å. The Al(4)-O(10) bond length is 1.93 Å. The Al(4)-O(20) bond length is 1.71 Å. The Al(4)-O(4) bond length is 1.72 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 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 trigonal pyramid. The Si(1)-O(1) bond length is 1.71 Å. The Si(1)-O(10) bond length is 1.73 Å. The Si(1)-O(12) bond length is 1.58 Å. The Si(1)-O(3) bond length is 1.59 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 Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Al(4)O4 trigonal pyramid, and  an edgeedge with one Al(3)O4 tetrahedra. The Si(2)-O(11) bond length is 1.58 Å. The Si(2)-O(2) bond length is 1.71 Å. The Si(2)-O(4) bond length is 1.59 Å. The Si(2)-O(9) bond length is 1.72 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 and  an edgeedge with one Si(5)O4 tetrahedra. The Si(3)-O(15) bond length is 1.77 Å. The Si(3)-O(18) bond length is 1.62 Å. The Si(3)-O(5) bond length is 1.59 Å. The Si(3)-O(7) bond length is 1.73 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 and  an edgeedge with one Si(6)O4 tetrahedra. The Si(4)-O(16) bond length is 1.77 Å. The Si(4)-O(17) bond length is 1.62 Å. The Si(4)-O(6) bond length is 1.59 Å. The Si(4)-O(8) bond length is 1.73 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 Al(2)O4 tetrahedra,  a cornercorner with one Al(4)O4 trigonal pyramid, and  an edgeedge with one Si(3)O4 tetrahedra. The Si(5)-O(13) bond length is 1.61 Å. The Si(5)-O(15) bond length is 1.74 Å. The Si(5)-O(20) bond length is 1.61 Å. The Si(5)-O(7) bond length is 1.69 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 Al(1)O4 tetrahedra,  a cornercorner with one Al(3)O4 tetrahedra, and  an edgeedge with one Si(4)O4 tetrahedra. The Si(6)-O(14) bond length is 1.61 Å. The Si(6)-O(16) bond length is 1.74 Å. The Si(6)-O(19) bond length is 1.61 Å. The Si(6)-O(8) bond length is 1.69 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 bent 150 degrees geometry to 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 water-like geometry to one Ca(2) and one Si(3) atom. In the sixth O site, O(6) is bonded in a water-like geometry to one Ca(1) and one Si(4) atom. In the seventh O site, O(7) is bonded in an L-shaped geometry to one Si(3) and one Si(5) atom. In the eighth O site, O(8) is bonded in an L-shaped geometry to one Si(4) and one Si(6) atom. In the ninth O site, O(9) is bonded to one Ca(1), one Ca(2), one Al(3), and one Si(2) atom to form distorted corner-sharing OCa2AlSi tetrahedra. In the tenth O site, O(10) is bonded to one Ca(1), one Ca(2), one Al(4), and one Si(1) atom to form distorted corner-sharing OCa2AlSi tetrahedra. In the eleventh O site, O(11) is bonded in a bent 150 degrees 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 water-like geometry to one Al(2) and one Si(5) atom. In the fourteenth O site, O(14) is bonded in a water-like geometry to one Al(1) and one Si(6) atom. In the fifteenth O site, O(15) is bonded in a distorted L-shaped geometry to one Si(3) and one Si(5) atom. In the sixteenth O site, O(16) is bonded in a distorted L-shaped geometry to one Ca(1), 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.