The crystal structure described by NaCa2Fe5(SiO3)8 is Esseneite-derived structured and crystallizes in the monoclinic C2/m space group. Na(1) is bonded in a linear geometry to two equivalent O(7) atoms. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra, and edges with two equivalent Fe(1)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-63°. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-60°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom. In the second O site, O(2) is bonded to one Ca(1), one Fe(1), one Fe(2), and one Si(2) atom to form a mixture of distorted edge and corner-sharing OCaFe2Si trigonal pyramids. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Fe(3) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ca(1), one Fe(2), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ca(1), one Si(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ca(1), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Si(1) atoms. is represented by the CIF file [CIF]
data_NaCa2Fe5(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.508
_cell_length_b   10.508
_cell_length_c   5.335
_cell_angle_alpha   82.830
_cell_angle_beta   82.830
_cell_angle_gamma   122.062
_symmetry_Int_Tables_number   1
_cell_volume   482.348
_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
  Na  Na0  1  0.500  0.500  0.000  1.0
  Ca  Ca1  1  0.276  0.724  0.500  1.0
  Ca  Ca2  1  0.724  0.276  0.500  1.0
  Fe  Fe3  1  0.079  0.921  0.500  1.0
  Fe  Fe4  1  0.921  0.079  0.500  1.0
  Fe  Fe5  1  0.178  0.822  0.000  1.0
  Fe  Fe6  1  0.822  0.178  0.000  1.0
  Fe  Fe7  1  0.000  0.000  0.000  1.0
  Si  Si8  1  0.806  0.638  0.299  1.0
  Si  Si9  1  0.638  0.806  0.299  1.0
  Si  Si10  1  0.194  0.362  0.701  1.0
  Si  Si11  1  0.362  0.194  0.701  1.0
  Si  Si12  1  0.882  0.543  0.803  1.0
  Si  Si13  1  0.543  0.882  0.803  1.0
  Si  Si14  1  0.118  0.457  0.197  1.0
  Si  Si15  1  0.457  0.118  0.197  1.0
  O  O16  1  0.975  0.795  0.221  1.0
  O  O17  1  0.795  0.975  0.221  1.0
  O  O18  1  0.025  0.205  0.779  1.0
  O  O19  1  0.205  0.025  0.779  1.0
  O  O20  1  0.051  0.706  0.718  1.0
  O  O21  1  0.706  0.051  0.718  1.0
  O  O22  1  0.949  0.294  0.282  1.0
  O  O23  1  0.294  0.949  0.282  1.0
  O  O24  1  0.896  0.896  0.719  1.0
  O  O25  1  0.104  0.104  0.281  1.0
  O  O26  1  0.877  0.389  0.790  1.0
  O  O27  1  0.389  0.877  0.790  1.0
  O  O28  1  0.123  0.611  0.210  1.0
  O  O29  1  0.611  0.123  0.210  1.0
  O  O30  1  0.786  0.522  0.101  1.0
  O  O31  1  0.522  0.786  0.101  1.0
  O  O32  1  0.214  0.478  0.899  1.0
  O  O33  1  0.478  0.214  0.899  1.0
  O  O34  1  0.769  0.539  0.596  1.0
  O  O35  1  0.539  0.769  0.596  1.0
  O  O36  1  0.231  0.461  0.404  1.0
  O  O37  1  0.461  0.231  0.404  1.0
  O  O38  1  0.663  0.663  0.288  1.0
  O  O39  1  0.337  0.337  0.712  1.0
[/CIF]
.
The crystal structure described by NaCa2Fe5(SiO3)8 is Esseneite-derived structured and crystallizes in the monoclinic C2/m space group. Na(1) is bonded in a linear geometry to two equivalent O(7) atoms. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra,  an edgeedge with one Fe(3)O6 octahedra, and edges with two equivalent Fe(1)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 55-63°. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-60°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Fe(1), one Fe(2), one Fe(3), and one Si(1) atom. In the second O site, O(2) is bonded to one Ca(1), one Fe(1), one Fe(2), and one Si(2) atom to form a mixture of distorted edge and corner-sharing OCaFe2Si trigonal pyramids. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Fe(3) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ca(1), one Fe(2), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to one Ca(1), one Si(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ca(1), one Si(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Na(1) and two equivalent Si(1) atoms. is represented by the CIF file [CIF]
data_NaCa2Fe5(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.508
_cell_length_b   10.508
_cell_length_c   5.335
_cell_angle_alpha   82.830
_cell_angle_beta   82.830
_cell_angle_gamma   122.062
_symmetry_Int_Tables_number   1
_cell_volume   482.348
_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
  Na  Na0  1  0.500  0.500  0.000  1.0
  Ca  Ca1  1  0.276  0.724  0.500  1.0
  Ca  Ca2  1  0.724  0.276  0.500  1.0
  Fe  Fe3  1  0.079  0.921  0.500  1.0
  Fe  Fe4  1  0.921  0.079  0.500  1.0
  Fe  Fe5  1  0.178  0.822  0.000  1.0
  Fe  Fe6  1  0.822  0.178  0.000  1.0
  Fe  Fe7  1  0.000  0.000  0.000  1.0
  Si  Si8  1  0.806  0.638  0.299  1.0
  Si  Si9  1  0.638  0.806  0.299  1.0
  Si  Si10  1  0.194  0.362  0.701  1.0
  Si  Si11  1  0.362  0.194  0.701  1.0
  Si  Si12  1  0.882  0.543  0.803  1.0
  Si  Si13  1  0.543  0.882  0.803  1.0
  Si  Si14  1  0.118  0.457  0.197  1.0
  Si  Si15  1  0.457  0.118  0.197  1.0
  O  O16  1  0.975  0.795  0.221  1.0
  O  O17  1  0.795  0.975  0.221  1.0
  O  O18  1  0.025  0.205  0.779  1.0
  O  O19  1  0.205  0.025  0.779  1.0
  O  O20  1  0.051  0.706  0.718  1.0
  O  O21  1  0.706  0.051  0.718  1.0
  O  O22  1  0.949  0.294  0.282  1.0
  O  O23  1  0.294  0.949  0.282  1.0
  O  O24  1  0.896  0.896  0.719  1.0
  O  O25  1  0.104  0.104  0.281  1.0
  O  O26  1  0.877  0.389  0.790  1.0
  O  O27  1  0.389  0.877  0.790  1.0
  O  O28  1  0.123  0.611  0.210  1.0
  O  O29  1  0.611  0.123  0.210  1.0
  O  O30  1  0.786  0.522  0.101  1.0
  O  O31  1  0.522  0.786  0.101  1.0
  O  O32  1  0.214  0.478  0.899  1.0
  O  O33  1  0.478  0.214  0.899  1.0
  O  O34  1  0.769  0.539  0.596  1.0
  O  O35  1  0.539  0.769  0.596  1.0
  O  O36  1  0.231  0.461  0.404  1.0
  O  O37  1  0.461  0.231  0.404  1.0
  O  O38  1  0.663  0.663  0.288  1.0
  O  O39  1  0.337  0.337  0.712  1.0
[/CIF]
.