The structure described by NaCa2(SiO3)3 is Esseneite-like structured and crystallizes in the triclinic P-1 space group. Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(2), one O(3), one O(6), and two equivalent O(5) atoms to form CaO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and edges with three equivalent Ca(2)O6 octahedra. In the second Ca site, Ca(2) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(6) atoms to form CaO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ca(2)O6 octahedra, and edges with three equivalent Ca(1)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(5), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra, corners with three 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 37-64°. In the second Si site, Si(2) is bonded to one O(4), one O(6), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with three equivalent Ca(2)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 36-66°. In the third Si site, Si(3) is bonded to one O(1), one O(2), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-58°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Ca(2), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Na(1), one Ca(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Ca(2), and one Si(2) atom. In the fifth O site, O(5) is bonded to one Ca(2), two equivalent Ca(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the sixth O site, O(6) is bonded to one Ca(1), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Na(1), one Si(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Na(1), one Si(1), and one Si(2) atom. is represented by the CIF card [CIF]
data_NaCa2(SiO3)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.011
_cell_length_b   7.163
_cell_length_c   8.093
_cell_angle_alpha   95.737
_cell_angle_beta   102.329
_cell_angle_gamma   90.208
_symmetry_Int_Tables_number   1
_cell_volume   394.904
_cell_formula_units_Z   2
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
  Na  Na0  1  0.267  0.348  0.562  1.0
  Na  Na1  1  0.733  0.652  0.438  1.0
  Ca  Ca2  1  0.589  0.149  0.856  1.0
  Ca  Ca3  1  0.411  0.851  0.144  1.0
  Ca  Ca4  1  0.087  0.140  0.849  1.0
  Ca  Ca5  1  0.913  0.860  0.151  1.0
  Si  Si6  1  0.594  0.663  0.781  1.0
  Si  Si7  1  0.406  0.337  0.219  1.0
  Si  Si8  1  0.050  0.658  0.784  1.0
  Si  Si9  1  0.950  0.342  0.216  1.0
  Si  Si10  1  0.266  0.855  0.548  1.0
  Si  Si11  1  0.734  0.145  0.452  1.0
  O  O12  1  0.789  0.130  0.654  1.0
  O  O13  1  0.211  0.870  0.346  1.0
  O  O14  1  0.295  0.053  0.668  1.0
  O  O15  1  0.705  0.947  0.332  1.0
  O  O16  1  0.505  0.457  0.806  1.0
  O  O17  1  0.495  0.543  0.194  1.0
  O  O18  1  0.150  0.456  0.817  1.0
  O  O19  1  0.850  0.544  0.183  1.0
  O  O20  1  0.611  0.828  0.935  1.0
  O  O21  1  0.389  0.172  0.065  1.0
  O  O22  1  0.107  0.824  0.940  1.0
  O  O23  1  0.893  0.176  0.060  1.0
  O  O24  1  0.468  0.729  0.599  1.0
  O  O25  1  0.532  0.271  0.401  1.0
  O  O26  1  0.092  0.726  0.605  1.0
  O  O27  1  0.908  0.274  0.395  1.0
  O  O28  1  0.811  0.614  0.738  1.0
  O  O29  1  0.189  0.386  0.262  1.0
[/CIF]
.
The structure described by NaCa2(SiO3)3 is Esseneite-like structured and crystallizes in the triclinic P-1 space group. Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(1), one O(2), one O(3), one O(6), and two equivalent O(5) atoms to form CaO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra,  an edgeedge with one Ca(1)O6 octahedra, and edges with three equivalent Ca(2)O6 octahedra. In the second Ca site, Ca(2) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(6) atoms to form CaO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra,  an edgeedge with one Ca(2)O6 octahedra, and edges with three equivalent Ca(1)O6 octahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(5), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(2)O6 octahedra, corners with three 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 37-64°. In the second Si site, Si(2) is bonded to one O(4), one O(6), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra, corners with three equivalent Ca(2)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 36-66°. In the third Si site, Si(3) is bonded to one O(1), one O(2), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-58°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ca(2), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Ca(1), one Ca(2), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Na(1), one Ca(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Ca(2), and one Si(2) atom. In the fifth O site, O(5) is bonded to one Ca(2), two equivalent Ca(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the sixth O site, O(6) is bonded to one Ca(1), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 2-coordinate geometry to one Na(1), one Si(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Na(1), one Si(1), and one Si(2) atom. is represented by the CIF card [CIF]
data_NaCa2(SiO3)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.011
_cell_length_b   7.163
_cell_length_c   8.093
_cell_angle_alpha   95.737
_cell_angle_beta   102.329
_cell_angle_gamma   90.208
_symmetry_Int_Tables_number   1
_cell_volume   394.904
_cell_formula_units_Z   2
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
  Na  Na0  1  0.267  0.348  0.562  1.0
  Na  Na1  1  0.733  0.652  0.438  1.0
  Ca  Ca2  1  0.589  0.149  0.856  1.0
  Ca  Ca3  1  0.411  0.851  0.144  1.0
  Ca  Ca4  1  0.087  0.140  0.849  1.0
  Ca  Ca5  1  0.913  0.860  0.151  1.0
  Si  Si6  1  0.594  0.663  0.781  1.0
  Si  Si7  1  0.406  0.337  0.219  1.0
  Si  Si8  1  0.050  0.658  0.784  1.0
  Si  Si9  1  0.950  0.342  0.216  1.0
  Si  Si10  1  0.266  0.855  0.548  1.0
  Si  Si11  1  0.734  0.145  0.452  1.0
  O  O12  1  0.789  0.130  0.654  1.0
  O  O13  1  0.211  0.870  0.346  1.0
  O  O14  1  0.295  0.053  0.668  1.0
  O  O15  1  0.705  0.947  0.332  1.0
  O  O16  1  0.505  0.457  0.806  1.0
  O  O17  1  0.495  0.543  0.194  1.0
  O  O18  1  0.150  0.456  0.817  1.0
  O  O19  1  0.850  0.544  0.183  1.0
  O  O20  1  0.611  0.828  0.935  1.0
  O  O21  1  0.389  0.172  0.065  1.0
  O  O22  1  0.107  0.824  0.940  1.0
  O  O23  1  0.893  0.176  0.060  1.0
  O  O24  1  0.468  0.729  0.599  1.0
  O  O25  1  0.532  0.271  0.401  1.0
  O  O26  1  0.092  0.726  0.605  1.0
  O  O27  1  0.908  0.274  0.395  1.0
  O  O28  1  0.811  0.614  0.738  1.0
  O  O29  1  0.189  0.386  0.262  1.0
[/CIF]
.