The crystal structure described by Ca6Si6O19 crystallizes in the triclinic P-1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(10), one O(9), two equivalent O(3), and two equivalent O(4) atoms to form distorted CaO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Ca(1)O6 octahedra. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(10), one O(3), one O(5), one O(8), one O(9), and two equivalent O(7) atoms. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one O(10), one O(4), one O(6), one O(7), one O(9), and two equivalent O(8) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(4), one O(5), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-66°. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(6), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-65°. In the third Si site, Si(3) is bonded to one O(1), one O(5), one O(6), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Si(3) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(3), two equivalent Ca(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Ca(2), one Si(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(3), one Si(2), and one Si(3) atom. In the seventh O site, O(7) is bonded to one Ca(3), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si trigonal pyramids. In the eighth O site, O(8) is bonded to one Ca(2), two equivalent Ca(3), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the ninth O site, O(9) is bonded to one Ca(1), one Ca(2), one Ca(3), and one Si(3) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the tenth O site, O(10) is bonded in a trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Ca(3) atom. is represented by the CIF card [CIF]
data_Ca6Si6O19
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.410
_cell_length_b   7.934
_cell_length_c   8.896
_cell_angle_alpha   84.065
_cell_angle_beta   77.981
_cell_angle_gamma   62.184
_symmetry_Int_Tables_number   1
_cell_volume   452.424
_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  0.746  0.508  0.495  1.0
  Ca  Ca1  1  0.254  0.492  0.505  1.0
  Ca  Ca2  1  0.670  0.337  0.130  1.0
  Ca  Ca3  1  0.330  0.663  0.870  1.0
  Ca  Ca4  1  0.181  0.336  0.135  1.0
  Ca  Ca5  1  0.819  0.664  0.865  1.0
  Si  Si6  1  0.910  0.763  0.208  1.0
  Si  Si7  1  0.090  0.237  0.792  1.0
  Si  Si8  1  0.478  0.771  0.215  1.0
  Si  Si9  1  0.522  0.229  0.785  1.0
  Si  Si10  1  0.020  0.057  0.319  1.0
  Si  Si11  1  0.980  0.943  0.681  1.0
  O  O12  1  0.000  0.000  0.500  1.0
  O  O13  1  0.661  0.832  0.219  1.0
  O  O14  1  0.339  0.168  0.781  1.0
  O  O15  1  0.470  0.622  0.352  1.0
  O  O16  1  0.530  0.378  0.648  1.0
  O  O17  1  0.999  0.607  0.342  1.0
  O  O18  1  0.001  0.393  0.658  1.0
  O  O19  1  0.917  0.967  0.225  1.0
  O  O20  1  0.083  0.033  0.775  1.0
  O  O21  1  0.265  0.981  0.235  1.0
  O  O22  1  0.735  0.019  0.765  1.0
  O  O23  1  0.523  0.675  0.049  1.0
  O  O24  1  0.477  0.325  0.951  1.0
  O  O25  1  0.035  0.665  0.042  1.0
  O  O26  1  0.965  0.335  0.958  1.0
  O  O27  1  0.907  0.284  0.294  1.0
  O  O28  1  0.093  0.716  0.706  1.0
  O  O29  1  0.409  0.291  0.295  1.0
  O  O30  1  0.591  0.709  0.705  1.0
[/CIF]
.
The crystal structure described by Ca6Si6O19 crystallizes in the triclinic P-1 space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(10), one O(9), two equivalent O(3), and two equivalent O(4) atoms to form distorted CaO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Ca(1)O6 octahedra. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(10), one O(3), one O(5), one O(8), one O(9), and two equivalent O(7) atoms. In the third Ca site, Ca(3) is bonded in a 7-coordinate geometry to one O(10), one O(4), one O(6), one O(7), one O(9), and two equivalent O(8) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(4), one O(5), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 37-66°. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(6), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-65°. In the third Si site, Si(3) is bonded to one O(1), one O(5), one O(6), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. There are ten inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Si(3) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(3), two equivalent Ca(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Ca(2), one Si(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ca(3), one Si(2), and one Si(3) atom. In the seventh O site, O(7) is bonded to one Ca(3), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si trigonal pyramids. In the eighth O site, O(8) is bonded to one Ca(2), two equivalent Ca(3), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the ninth O site, O(9) is bonded to one Ca(1), one Ca(2), one Ca(3), and one Si(3) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the tenth O site, O(10) is bonded in a trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Ca(3) atom. is represented by the CIF card [CIF]
data_Ca6Si6O19
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.410
_cell_length_b   7.934
_cell_length_c   8.896
_cell_angle_alpha   84.065
_cell_angle_beta   77.981
_cell_angle_gamma   62.184
_symmetry_Int_Tables_number   1
_cell_volume   452.424
_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  0.746  0.508  0.495  1.0
  Ca  Ca1  1  0.254  0.492  0.505  1.0
  Ca  Ca2  1  0.670  0.337  0.130  1.0
  Ca  Ca3  1  0.330  0.663  0.870  1.0
  Ca  Ca4  1  0.181  0.336  0.135  1.0
  Ca  Ca5  1  0.819  0.664  0.865  1.0
  Si  Si6  1  0.910  0.763  0.208  1.0
  Si  Si7  1  0.090  0.237  0.792  1.0
  Si  Si8  1  0.478  0.771  0.215  1.0
  Si  Si9  1  0.522  0.229  0.785  1.0
  Si  Si10  1  0.020  0.057  0.319  1.0
  Si  Si11  1  0.980  0.943  0.681  1.0
  O  O12  1  0.000  0.000  0.500  1.0
  O  O13  1  0.661  0.832  0.219  1.0
  O  O14  1  0.339  0.168  0.781  1.0
  O  O15  1  0.470  0.622  0.352  1.0
  O  O16  1  0.530  0.378  0.648  1.0
  O  O17  1  0.999  0.607  0.342  1.0
  O  O18  1  0.001  0.393  0.658  1.0
  O  O19  1  0.917  0.967  0.225  1.0
  O  O20  1  0.083  0.033  0.775  1.0
  O  O21  1  0.265  0.981  0.235  1.0
  O  O22  1  0.735  0.019  0.765  1.0
  O  O23  1  0.523  0.675  0.049  1.0
  O  O24  1  0.477  0.325  0.951  1.0
  O  O25  1  0.035  0.665  0.042  1.0
  O  O26  1  0.965  0.335  0.958  1.0
  O  O27  1  0.907  0.284  0.294  1.0
  O  O28  1  0.093  0.716  0.706  1.0
  O  O29  1  0.409  0.291  0.295  1.0
  O  O30  1  0.591  0.709  0.705  1.0
[/CIF]
.