The material described by CaAl2SiO6 is Esseneite-like structured and crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(4), one O(5), two equivalent O(3), and two equivalent O(6) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form AlO4 tetrahedra that share corners with three equivalent Al(2)O6 octahedra and corners with two equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-65°. In the second Al site, Al(2) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form AlO6 octahedra that share corners with three equivalent Al(1)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and edges with two equivalent Al(2)O6 octahedra. Si(1) is bonded to one O(4), one O(5), and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with three equivalent Al(2)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-57°. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Al(1), and two equivalent Al(2) atoms to form distorted corner-sharing OCaAl3 tetrahedra. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(1), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ca(1) and two equivalent Al(1) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Al(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ca(1), one Al(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and two equivalent Si(1) atoms. is represented by the CIF card [CIF]
data_CaAl2SiO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.759
_cell_length_b   5.330
_cell_length_c   9.786
_cell_angle_alpha   73.381
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   437.768
_cell_formula_units_Z   4
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  0.938  0.748  0.768  1.0
  Ca  Ca1  1  0.438  0.752  0.232  1.0
  Ca  Ca2  1  0.562  0.248  0.768  1.0
  Ca  Ca3  1  0.062  0.252  0.232  1.0
  Al  Al4  1  0.153  0.794  0.038  1.0
  Al  Al5  1  0.653  0.706  0.962  1.0
  Al  Al6  1  0.847  0.206  0.962  1.0
  Al  Al7  1  0.347  0.294  0.038  1.0
  Al  Al8  1  0.341  0.760  0.757  1.0
  Al  Al9  1  0.841  0.740  0.243  1.0
  Al  Al10  1  0.159  0.260  0.757  1.0
  Al  Al11  1  0.659  0.240  0.243  1.0
  Si  Si12  1  0.654  0.779  0.536  1.0
  Si  Si13  1  0.154  0.721  0.464  1.0
  Si  Si14  1  0.346  0.221  0.464  1.0
  Si  Si15  1  0.846  0.279  0.536  1.0
  O  O16  1  0.170  0.892  0.846  1.0
  O  O17  1  0.978  0.677  0.117  1.0
  O  O18  1  0.226  0.027  0.114  1.0
  O  O19  1  0.666  0.867  0.362  1.0
  O  O20  1  0.491  0.705  0.615  1.0
  O  O21  1  0.742  0.005  0.596  1.0
  O  O22  1  0.166  0.633  0.638  1.0
  O  O23  1  0.991  0.795  0.385  1.0
  O  O24  1  0.242  0.495  0.404  1.0
  O  O25  1  0.670  0.608  0.154  1.0
  O  O26  1  0.478  0.823  0.883  1.0
  O  O27  1  0.726  0.473  0.886  1.0
  O  O28  1  0.334  0.133  0.638  1.0
  O  O29  1  0.509  0.295  0.385  1.0
  O  O30  1  0.258  0.995  0.404  1.0
  O  O31  1  0.830  0.108  0.154  1.0
  O  O32  1  0.022  0.323  0.883  1.0
  O  O33  1  0.774  0.973  0.886  1.0
  O  O34  1  0.330  0.392  0.846  1.0
  O  O35  1  0.522  0.177  0.117  1.0
  O  O36  1  0.274  0.527  0.114  1.0
  O  O37  1  0.834  0.367  0.362  1.0
  O  O38  1  0.009  0.205  0.615  1.0
  O  O39  1  0.758  0.505  0.596  1.0
[/CIF]
.
The material described by CaAl2SiO6 is Esseneite-like structured and crystallizes in the monoclinic P2_1/c space group. Ca(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(4), one O(5), two equivalent O(3), and two equivalent O(6) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form AlO4 tetrahedra that share corners with three equivalent Al(2)O6 octahedra and corners with two equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 40-65°. In the second Al site, Al(2) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form AlO6 octahedra that share corners with three equivalent Al(1)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and edges with two equivalent Al(2)O6 octahedra. Si(1) is bonded to one O(4), one O(5), and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with three equivalent Al(2)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-57°. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Al(1), and two equivalent Al(2) atoms to form distorted corner-sharing OCaAl3 tetrahedra. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ca(1), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ca(1) and two equivalent Al(1) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), two equivalent Al(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ca(1), one Al(2), and one Si(1) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and two equivalent Si(1) atoms. is represented by the CIF card [CIF]
data_CaAl2SiO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.759
_cell_length_b   5.330
_cell_length_c   9.786
_cell_angle_alpha   73.381
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   437.768
_cell_formula_units_Z   4
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  0.938  0.748  0.768  1.0
  Ca  Ca1  1  0.438  0.752  0.232  1.0
  Ca  Ca2  1  0.562  0.248  0.768  1.0
  Ca  Ca3  1  0.062  0.252  0.232  1.0
  Al  Al4  1  0.153  0.794  0.038  1.0
  Al  Al5  1  0.653  0.706  0.962  1.0
  Al  Al6  1  0.847  0.206  0.962  1.0
  Al  Al7  1  0.347  0.294  0.038  1.0
  Al  Al8  1  0.341  0.760  0.757  1.0
  Al  Al9  1  0.841  0.740  0.243  1.0
  Al  Al10  1  0.159  0.260  0.757  1.0
  Al  Al11  1  0.659  0.240  0.243  1.0
  Si  Si12  1  0.654  0.779  0.536  1.0
  Si  Si13  1  0.154  0.721  0.464  1.0
  Si  Si14  1  0.346  0.221  0.464  1.0
  Si  Si15  1  0.846  0.279  0.536  1.0
  O  O16  1  0.170  0.892  0.846  1.0
  O  O17  1  0.978  0.677  0.117  1.0
  O  O18  1  0.226  0.027  0.114  1.0
  O  O19  1  0.666  0.867  0.362  1.0
  O  O20  1  0.491  0.705  0.615  1.0
  O  O21  1  0.742  0.005  0.596  1.0
  O  O22  1  0.166  0.633  0.638  1.0
  O  O23  1  0.991  0.795  0.385  1.0
  O  O24  1  0.242  0.495  0.404  1.0
  O  O25  1  0.670  0.608  0.154  1.0
  O  O26  1  0.478  0.823  0.883  1.0
  O  O27  1  0.726  0.473  0.886  1.0
  O  O28  1  0.334  0.133  0.638  1.0
  O  O29  1  0.509  0.295  0.385  1.0
  O  O30  1  0.258  0.995  0.404  1.0
  O  O31  1  0.830  0.108  0.154  1.0
  O  O32  1  0.022  0.323  0.883  1.0
  O  O33  1  0.774  0.973  0.886  1.0
  O  O34  1  0.330  0.392  0.846  1.0
  O  O35  1  0.522  0.177  0.117  1.0
  O  O36  1  0.274  0.527  0.114  1.0
  O  O37  1  0.834  0.367  0.362  1.0
  O  O38  1  0.009  0.205  0.615  1.0
  O  O39  1  0.758  0.505  0.596  1.0
[/CIF]
.