Ca2MgAl2(SiO4)3 is Esseneite-derived structured and crystallizes in the triclinic P1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(2), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. Mg(1) is bonded to one O(11), one O(12), one O(5), one O(6), one O(7), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and edges with two equivalent Al(2)O6 octahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(4), one O(5), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-68°. In the second Al site, Al(2) is bonded to one O(10), one O(5), one O(6), one O(7), one O(8), and one O(9) atom to form AlO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Al(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-61°. In the second Si site, Si(2) is bonded to one O(11), one O(2), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-61°. In the third Si site, Si(3) is bonded to one O(1), one O(12), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and corners with two equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-61°. There are twelve 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 Al(1), and one Si(3) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), one Si(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 Ca(2), one Al(1), and one Si(3) atom. In the fifth O site, O(5) is bonded to one Ca(1), one Mg(1), one Al(1), and one Al(2) atom to form distorted edge-sharing OCaMgAl2 tetrahedra. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(1), one Al(2), and one Si(1) atom. In the seventh O site, O(7) is bonded to one Ca(2), one Mg(1), one Al(2), and one Si(2) atom to form distorted edge-sharing OCaMgAlSi tetrahedra. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Ca(2), one Mg(1), one Al(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Ca(2), one Al(1), and one Al(2) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Ca(2), one Al(2), and one Si(1) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(1), and one Si(2) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(1), and one Si(3) atom.
Ca2MgAl2(SiO4)3 is Esseneite-derived structured and crystallizes in the triclinic P1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. The Ca(1)-O(1) bond length is 2.53 Å. The Ca(1)-O(11) bond length is 2.43 Å. The Ca(1)-O(12) bond length is 2.38 Å. The Ca(1)-O(2) bond length is 2.62 Å. The Ca(1)-O(3) bond length is 2.75 Å. The Ca(1)-O(4) bond length is 2.65 Å. The Ca(1)-O(5) bond length is 2.39 Å. The Ca(1)-O(6) bond length is 2.37 Å. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(2), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. The Ca(2)-O(1) bond length is 2.63 Å. The Ca(2)-O(10) bond length is 2.43 Å. The Ca(2)-O(2) bond length is 2.74 Å. The Ca(2)-O(3) bond length is 2.53 Å. The Ca(2)-O(4) bond length is 2.48 Å. The Ca(2)-O(7) bond length is 2.39 Å. The Ca(2)-O(8) bond length is 2.45 Å. The Ca(2)-O(9) bond length is 2.32 Å. Mg(1) is bonded to one O(11), one O(12), one O(5), one O(6), one O(7), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and edges with two equivalent Al(2)O6 octahedra. The Mg(1)-O(11) bond length is 2.05 Å. The Mg(1)-O(12) bond length is 2.05 Å. The Mg(1)-O(5) bond length is 2.06 Å. The Mg(1)-O(6) bond length is 2.11 Å. The Mg(1)-O(7) bond length is 2.15 Å. The Mg(1)-O(8) bond length is 2.18 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(4), one O(5), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-68°. The Al(1)-O(1) bond length is 1.77 Å. The Al(1)-O(4) bond length is 1.80 Å. The Al(1)-O(5) bond length is 1.76 Å. The Al(1)-O(9) bond length is 1.75 Å. In the second Al site, Al(2) is bonded to one O(10), one O(5), one O(6), one O(7), one O(8), and one O(9) atom to form AlO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Al(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. The Al(2)-O(10) bond length is 1.97 Å. The Al(2)-O(5) bond length is 1.92 Å. The Al(2)-O(6) bond length is 2.08 Å. The Al(2)-O(7) bond length is 1.98 Å. The Al(2)-O(8) bond length is 1.94 Å. The Al(2)-O(9) bond length is 1.87 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-61°. The Si(1)-O(10) bond length is 1.62 Å. The Si(1)-O(2) bond length is 1.67 Å. The Si(1)-O(3) bond length is 1.70 Å. The Si(1)-O(6) bond length is 1.63 Å. In the second Si site, Si(2) is bonded to one O(11), one O(2), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-61°. The Si(2)-O(11) bond length is 1.60 Å. The Si(2)-O(2) bond length is 1.70 Å. The Si(2)-O(3) bond length is 1.68 Å. The Si(2)-O(7) bond length is 1.64 Å. In the third Si site, Si(3) is bonded to one O(1), one O(12), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(2)O6 octahedra, corners with two equivalent Mg(1)O6 octahedra, and corners with two equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-61°. The Si(3)-O(1) bond length is 1.66 Å. The Si(3)-O(12) bond length is 1.61 Å. The Si(3)-O(4) bond length is 1.65 Å. The Si(3)-O(8) bond length is 1.66 Å. There are twelve 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 Al(1), and one Si(3) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), one Si(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 Ca(2), one Al(1), and one Si(3) atom. In the fifth O site, O(5) is bonded to one Ca(1), one Mg(1), one Al(1), and one Al(2) atom to form distorted edge-sharing OCaMgAl2 tetrahedra. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Mg(1), one Al(2), and one Si(1) atom. In the seventh O site, O(7) is bonded to one Ca(2), one Mg(1), one Al(2), and one Si(2) atom to form distorted edge-sharing OCaMgAlSi tetrahedra. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Ca(2), one Mg(1), one Al(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Ca(2), one Al(1), and one Al(2) atom. In the tenth O site, O(10) is bonded in a distorted T-shaped geometry to one Ca(2), one Al(2), and one Si(1) atom. In the eleventh O site, O(11) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(1), and one Si(2) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(1), and one Si(3) atom.