The material structure described by 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. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca2MgAl2(SiO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.352
_cell_length_b   6.591
_cell_length_c   6.601
_cell_angle_alpha   84.256
_cell_angle_beta   78.127
_cell_angle_gamma   77.449
_symmetry_Int_Tables_number   1
_cell_volume   222.044
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Ca  Ca0  1  0.254  0.692  0.298  1.0
  Ca  Ca1  1  0.756  0.300  0.689  1.0
  Mg  Mg2  1  0.745  0.909  0.091  1.0
  Al  Al3  1  0.279  0.188  0.385  1.0
  Al  Al4  1  0.247  0.093  0.912  1.0
  Si  Si5  1  0.226  0.617  0.807  1.0
  Si  Si6  1  0.721  0.807  0.622  1.0
  Si  Si7  1  0.780  0.383  0.197  1.0
  O  O8  1  0.523  0.336  0.370  1.0
  O  O9  1  0.990  0.635  0.672  1.0
  O  O10  1  0.493  0.664  0.634  1.0
  O  O11  1  0.001  0.383  0.339  1.0
  O  O12  1  0.351  0.026  0.176  1.0
  O  O13  1  0.144  0.802  0.969  1.0
  O  O14  1  0.619  0.979  0.799  1.0
  O  O15  1  0.883  0.200  0.026  1.0
  O  O16  1  0.178  0.106  0.644  1.0
  O  O17  1  0.315  0.377  0.888  1.0
  O  O18  1  0.811  0.891  0.388  1.0
  O  O19  1  0.683  0.613  0.096  1.0
[/CIF]
.
The material structure described by 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. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca2MgAl2(SiO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.352
_cell_length_b   6.591
_cell_length_c   6.601
_cell_angle_alpha   84.256
_cell_angle_beta   78.127
_cell_angle_gamma   77.449
_symmetry_Int_Tables_number   1
_cell_volume   222.044
_cell_formula_units_Z   1
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Ca  Ca0  1  0.254  0.692  0.298  1.0
  Ca  Ca1  1  0.756  0.300  0.689  1.0
  Mg  Mg2  1  0.745  0.909  0.091  1.0
  Al  Al3  1  0.279  0.188  0.385  1.0
  Al  Al4  1  0.247  0.093  0.912  1.0
  Si  Si5  1  0.226  0.617  0.807  1.0
  Si  Si6  1  0.721  0.807  0.622  1.0
  Si  Si7  1  0.780  0.383  0.197  1.0
  O  O8  1  0.523  0.336  0.370  1.0
  O  O9  1  0.990  0.635  0.672  1.0
  O  O10  1  0.493  0.664  0.634  1.0
  O  O11  1  0.001  0.383  0.339  1.0
  O  O12  1  0.351  0.026  0.176  1.0
  O  O13  1  0.144  0.802  0.969  1.0
  O  O14  1  0.619  0.979  0.799  1.0
  O  O15  1  0.883  0.200  0.026  1.0
  O  O16  1  0.178  0.106  0.644  1.0
  O  O17  1  0.315  0.377  0.888  1.0
  O  O18  1  0.811  0.891  0.388  1.0
  O  O19  1  0.683  0.613  0.096  1.0
[/CIF]
.