The structure described by CaNaAlSi2O7 crystallizes in the orthorhombic P2_12_12_1 space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and two equivalent O(4) atoms. Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and one O(7) atom. Al(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form AlO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with two equivalent Al(1)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with two equivalent Al(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted tetrahedral geometry to one Na(1), one Ca(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), one Ca(1), one Al(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Na(1), one Al(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to two equivalent Na(1), one Al(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ca(1), one Al(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Na(1), one Ca(1), and one Si(1) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Ca(1) and one Si(2) atom. is represented by the CIF file [CIF]
data_NaCaAlSi2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.504
_cell_length_b   7.685
_cell_length_c   7.873
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   696.028
_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
  Na  Na0  1  0.913  0.768  0.284  1.0
  Na  Na1  1  0.587  0.732  0.784  1.0
  Na  Na2  1  0.413  0.232  0.716  1.0
  Na  Na3  1  0.087  0.268  0.216  1.0
  Ca  Ca4  1  0.105  0.066  0.594  1.0
  Ca  Ca5  1  0.395  0.434  0.094  1.0
  Ca  Ca6  1  0.605  0.934  0.406  1.0
  Ca  Ca7  1  0.895  0.566  0.906  1.0
  Al  Al8  1  0.992  0.992  0.991  1.0
  Al  Al9  1  0.492  0.008  0.009  1.0
  Al  Al10  1  0.508  0.508  0.491  1.0
  Al  Al11  1  0.008  0.492  0.509  1.0
  Si  Si12  1  0.642  0.652  0.137  1.0
  Si  Si13  1  0.636  0.358  0.853  1.0
  Si  Si14  1  0.864  0.142  0.353  1.0
  Si  Si15  1  0.858  0.848  0.637  1.0
  Si  Si16  1  0.142  0.348  0.863  1.0
  Si  Si17  1  0.136  0.642  0.147  1.0
  Si  Si18  1  0.358  0.152  0.363  1.0
  Si  Si19  1  0.364  0.858  0.647  1.0
  O  O20  1  0.083  0.482  0.009  1.0
  O  O21  1  0.083  0.154  0.900  1.0
  O  O22  1  0.061  0.809  0.079  1.0
  O  O23  1  0.074  0.582  0.327  1.0
  O  O24  1  0.090  0.398  0.676  1.0
  O  O25  1  0.220  0.158  0.381  1.0
  O  O26  1  0.227  0.859  0.647  1.0
  O  O27  1  0.273  0.641  0.147  1.0
  O  O28  1  0.280  0.342  0.881  1.0
  O  O29  1  0.426  0.918  0.827  1.0
  O  O30  1  0.439  0.691  0.579  1.0
  O  O31  1  0.417  0.346  0.400  1.0
  O  O32  1  0.410  0.102  0.176  1.0
  O  O33  1  0.417  0.018  0.509  1.0
  O  O34  1  0.583  0.518  0.991  1.0
  O  O35  1  0.583  0.846  0.100  1.0
  O  O36  1  0.590  0.602  0.324  1.0
  O  O37  1  0.574  0.418  0.673  1.0
  O  O38  1  0.561  0.191  0.921  1.0
  O  O39  1  0.727  0.141  0.353  1.0
  O  O40  1  0.720  0.842  0.619  1.0
  O  O41  1  0.773  0.359  0.853  1.0
  O  O42  1  0.780  0.658  0.119  1.0
  O  O43  1  0.910  0.898  0.824  1.0
  O  O44  1  0.917  0.654  0.600  1.0
  O  O45  1  0.939  0.309  0.421  1.0
  O  O46  1  0.926  0.082  0.173  1.0
  O  O47  1  0.917  0.982  0.491  1.0
[/CIF]
.
The structure described by CaNaAlSi2O7 crystallizes in the orthorhombic P2_12_12_1 space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and two equivalent O(4) atoms. Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(5), one O(6), and one O(7) atom. Al(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form AlO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with two equivalent Al(1)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with two equivalent Al(1)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted tetrahedral geometry to one Na(1), one Ca(1), one Si(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), one Ca(1), one Al(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Na(1), one Al(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to two equivalent Na(1), one Al(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ca(1), one Al(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Na(1), one Ca(1), and one Si(1) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one Ca(1) and one Si(2) atom. is represented by the CIF file [CIF]
data_NaCaAlSi2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.504
_cell_length_b   7.685
_cell_length_c   7.873
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   696.028
_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
  Na  Na0  1  0.913  0.768  0.284  1.0
  Na  Na1  1  0.587  0.732  0.784  1.0
  Na  Na2  1  0.413  0.232  0.716  1.0
  Na  Na3  1  0.087  0.268  0.216  1.0
  Ca  Ca4  1  0.105  0.066  0.594  1.0
  Ca  Ca5  1  0.395  0.434  0.094  1.0
  Ca  Ca6  1  0.605  0.934  0.406  1.0
  Ca  Ca7  1  0.895  0.566  0.906  1.0
  Al  Al8  1  0.992  0.992  0.991  1.0
  Al  Al9  1  0.492  0.008  0.009  1.0
  Al  Al10  1  0.508  0.508  0.491  1.0
  Al  Al11  1  0.008  0.492  0.509  1.0
  Si  Si12  1  0.642  0.652  0.137  1.0
  Si  Si13  1  0.636  0.358  0.853  1.0
  Si  Si14  1  0.864  0.142  0.353  1.0
  Si  Si15  1  0.858  0.848  0.637  1.0
  Si  Si16  1  0.142  0.348  0.863  1.0
  Si  Si17  1  0.136  0.642  0.147  1.0
  Si  Si18  1  0.358  0.152  0.363  1.0
  Si  Si19  1  0.364  0.858  0.647  1.0
  O  O20  1  0.083  0.482  0.009  1.0
  O  O21  1  0.083  0.154  0.900  1.0
  O  O22  1  0.061  0.809  0.079  1.0
  O  O23  1  0.074  0.582  0.327  1.0
  O  O24  1  0.090  0.398  0.676  1.0
  O  O25  1  0.220  0.158  0.381  1.0
  O  O26  1  0.227  0.859  0.647  1.0
  O  O27  1  0.273  0.641  0.147  1.0
  O  O28  1  0.280  0.342  0.881  1.0
  O  O29  1  0.426  0.918  0.827  1.0
  O  O30  1  0.439  0.691  0.579  1.0
  O  O31  1  0.417  0.346  0.400  1.0
  O  O32  1  0.410  0.102  0.176  1.0
  O  O33  1  0.417  0.018  0.509  1.0
  O  O34  1  0.583  0.518  0.991  1.0
  O  O35  1  0.583  0.846  0.100  1.0
  O  O36  1  0.590  0.602  0.324  1.0
  O  O37  1  0.574  0.418  0.673  1.0
  O  O38  1  0.561  0.191  0.921  1.0
  O  O39  1  0.727  0.141  0.353  1.0
  O  O40  1  0.720  0.842  0.619  1.0
  O  O41  1  0.773  0.359  0.853  1.0
  O  O42  1  0.780  0.658  0.119  1.0
  O  O43  1  0.910  0.898  0.824  1.0
  O  O44  1  0.917  0.654  0.600  1.0
  O  O45  1  0.939  0.309  0.421  1.0
  O  O46  1  0.926  0.082  0.173  1.0
  O  O47  1  0.917  0.982  0.491  1.0
[/CIF]
.