The crystal structure described by NaCa3Fe4(SiO3)8 is Esseneite-derived structured and crystallizes in the monoclinic C2 space group. Na(1) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(11), two equivalent O(5), and two equivalent O(9) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(12), one O(2), one O(3), one O(4), one O(6), and one O(8) atom. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and edges with two equivalent Fe(2)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(5), one O(7), one O(8), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(3)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(12), two equivalent O(2), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and edges with two equivalent Fe(2)O6 octahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(11), one O(2), one O(3), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-62°. In the second Si site, Si(2) is bonded to one O(3), 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,  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  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-60°. In the third Si site, Si(3) is bonded to one O(10), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-60°. In the fourth Si site, Si(4) is bonded to one O(1), one O(10), one O(11), and one O(12) 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  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-60°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Fe(1), one Fe(2), and one Si(4) atom to form a mixture of distorted corner and edge-sharing OCaFe2Si trigonal pyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), one Fe(2), one Fe(3), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ca(2), one Fe(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Fe(2), one Fe(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), one Si(2), and one Si(3) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ca(1), one Fe(2), and one Si(3) atom. In the eighth O site, O(8) is bonded to one Ca(2), one Fe(1), one Fe(2), and one Si(3) atom to form a mixture of distorted corner and edge-sharing OCaFe2Si trigonal pyramids. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Na(1), one Fe(2), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Na(1), one Ca(2), one Si(3), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one Na(1), one Ca(2), one Si(1), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Ca(2), one Fe(3), and one Si(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_NaCa3Fe4(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.700
_cell_length_b   7.700
_cell_length_c   9.985
_cell_angle_alpha   62.792
_cell_angle_beta   62.792
_cell_angle_gamma   72.039
_symmetry_Int_Tables_number   1
_cell_volume   464.581
_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  0.673  0.327  0.500  1.0
  Ca  Ca1  1  0.173  0.827  0.000  1.0
  Ca  Ca2  1  0.326  0.180  0.247  1.0
  Ca  Ca3  1  0.820  0.674  0.753  1.0
  Fe  Fe4  1  0.783  0.217  0.000  1.0
  Fe  Fe5  1  0.721  0.775  0.254  1.0
  Fe  Fe6  1  0.283  0.717  0.500  1.0
  Fe  Fe7  1  0.225  0.279  0.746  1.0
  Si  Si8  1  0.524  0.962  0.545  1.0
  Si  Si9  1  0.460  0.527  0.791  1.0
  Si  Si10  1  0.028  0.458  0.043  1.0
  Si  Si11  1  0.038  0.476  0.455  1.0
  Si  Si12  1  0.960  0.024  0.297  1.0
  Si  Si13  1  0.976  0.040  0.703  1.0
  Si  Si14  1  0.542  0.972  0.957  1.0
  Si  Si15  1  0.473  0.540  0.209  1.0
  O  O16  1  0.921  0.985  0.168  1.0
  O  O17  1  0.474  0.911  0.424  1.0
  O  O18  1  0.486  0.768  0.723  1.0
  O  O19  1  0.659  0.413  0.824  1.0
  O  O20  1  0.405  0.501  0.663  1.0
  O  O21  1  0.587  0.341  0.176  1.0
  O  O22  1  0.270  0.484  0.971  1.0
  O  O23  1  0.232  0.514  0.277  1.0
  O  O24  1  0.916  0.657  0.073  1.0
  O  O25  1  0.989  0.416  0.914  1.0
  O  O26  1  0.841  0.593  0.423  1.0
  O  O27  1  0.995  0.263  0.219  1.0
  O  O28  1  0.021  0.234  0.528  1.0
  O  O29  1  0.159  0.911  0.335  1.0
  O  O30  1  0.015  0.079  0.832  1.0
  O  O31  1  0.089  0.841  0.665  1.0
  O  O32  1  0.766  0.979  0.472  1.0
  O  O33  1  0.737  0.005  0.781  1.0
  O  O34  1  0.407  0.159  0.577  1.0
  O  O35  1  0.584  0.011  0.086  1.0
  O  O36  1  0.343  0.084  0.927  1.0
  O  O37  1  0.516  0.730  0.029  1.0
  O  O38  1  0.499  0.595  0.337  1.0
  O  O39  1  0.089  0.526  0.576  1.0
[/CIF]
.
The crystal structure described by NaCa3Fe4(SiO3)8 is Esseneite-derived structured and crystallizes in the monoclinic C2 space group. Na(1) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(11), two equivalent O(5), and two equivalent O(9) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(12), one O(2), one O(3), one O(4), one O(6), and one O(8) atom. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and edges with two equivalent Fe(2)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(5), one O(7), one O(8), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra,  an edgeedge with one Fe(1)O6 octahedra, and  an edgeedge with one Fe(3)O6 octahedra. In the third Fe site, Fe(3) is bonded to two equivalent O(12), two equivalent O(2), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and edges with two equivalent Fe(2)O6 octahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(11), one O(2), one O(3), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(3)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-62°. In the second Si site, Si(2) is bonded to one O(3), 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,  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  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-60°. In the third Si site, Si(3) is bonded to one O(10), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 36-60°. In the fourth Si site, Si(4) is bonded to one O(1), one O(10), one O(11), and one O(12) 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  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-60°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Fe(1), one Fe(2), and one Si(4) atom to form a mixture of distorted corner and edge-sharing OCaFe2Si trigonal pyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), one Fe(2), one Fe(3), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), one Si(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ca(2), one Fe(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Fe(2), one Fe(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), one Si(2), and one Si(3) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ca(1), one Fe(2), and one Si(3) atom. In the eighth O site, O(8) is bonded to one Ca(2), one Fe(1), one Fe(2), and one Si(3) atom to form a mixture of distorted corner and edge-sharing OCaFe2Si trigonal pyramids. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one Na(1), one Fe(2), and one Si(1) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Na(1), one Ca(2), one Si(3), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one Na(1), one Ca(2), one Si(1), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Ca(2), one Fe(3), and one Si(4) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_NaCa3Fe4(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.700
_cell_length_b   7.700
_cell_length_c   9.985
_cell_angle_alpha   62.792
_cell_angle_beta   62.792
_cell_angle_gamma   72.039
_symmetry_Int_Tables_number   1
_cell_volume   464.581
_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  0.673  0.327  0.500  1.0
  Ca  Ca1  1  0.173  0.827  0.000  1.0
  Ca  Ca2  1  0.326  0.180  0.247  1.0
  Ca  Ca3  1  0.820  0.674  0.753  1.0
  Fe  Fe4  1  0.783  0.217  0.000  1.0
  Fe  Fe5  1  0.721  0.775  0.254  1.0
  Fe  Fe6  1  0.283  0.717  0.500  1.0
  Fe  Fe7  1  0.225  0.279  0.746  1.0
  Si  Si8  1  0.524  0.962  0.545  1.0
  Si  Si9  1  0.460  0.527  0.791  1.0
  Si  Si10  1  0.028  0.458  0.043  1.0
  Si  Si11  1  0.038  0.476  0.455  1.0
  Si  Si12  1  0.960  0.024  0.297  1.0
  Si  Si13  1  0.976  0.040  0.703  1.0
  Si  Si14  1  0.542  0.972  0.957  1.0
  Si  Si15  1  0.473  0.540  0.209  1.0
  O  O16  1  0.921  0.985  0.168  1.0
  O  O17  1  0.474  0.911  0.424  1.0
  O  O18  1  0.486  0.768  0.723  1.0
  O  O19  1  0.659  0.413  0.824  1.0
  O  O20  1  0.405  0.501  0.663  1.0
  O  O21  1  0.587  0.341  0.176  1.0
  O  O22  1  0.270  0.484  0.971  1.0
  O  O23  1  0.232  0.514  0.277  1.0
  O  O24  1  0.916  0.657  0.073  1.0
  O  O25  1  0.989  0.416  0.914  1.0
  O  O26  1  0.841  0.593  0.423  1.0
  O  O27  1  0.995  0.263  0.219  1.0
  O  O28  1  0.021  0.234  0.528  1.0
  O  O29  1  0.159  0.911  0.335  1.0
  O  O30  1  0.015  0.079  0.832  1.0
  O  O31  1  0.089  0.841  0.665  1.0
  O  O32  1  0.766  0.979  0.472  1.0
  O  O33  1  0.737  0.005  0.781  1.0
  O  O34  1  0.407  0.159  0.577  1.0
  O  O35  1  0.584  0.011  0.086  1.0
  O  O36  1  0.343  0.084  0.927  1.0
  O  O37  1  0.516  0.730  0.029  1.0
  O  O38  1  0.499  0.595  0.337  1.0
  O  O39  1  0.089  0.526  0.576  1.0
[/CIF]
.