The material structure described by Na3CaMgCr3(SiO3)8 is Esseneite-derived structured and crystallizes in the monoclinic P2 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(11), two equivalent O(3), two equivalent O(6), and two equivalent O(9) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(12), two equivalent O(4), and two equivalent O(5) atoms. In the third Na site, Na(3) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(12), two equivalent O(2), and two equivalent O(7) atoms. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(11), two equivalent O(8), and two equivalent O(9) atoms. Mg(1) is bonded to two equivalent O(1), two equivalent O(6), and two equivalent O(8) atoms to form MgO6 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 Cr(2)O6 octahedra. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and edges with two equivalent Cr(3)O6 octahedra. In the second Cr site, Cr(2) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(8) atoms to form CrO6 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 Mg(1)O6 octahedra. In the third Cr site, Cr(3) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and edges with two equivalent Cr(1)O6 octahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(11), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-60°. In the second Si site, Si(2) is bonded to one O(10), one O(12), one O(2), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-58°. In the third Si site, Si(3) is bonded to one O(11), one O(3), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-60°. In the fourth Si site, Si(4) is bonded to one O(10), one O(12), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-61°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Na(3), one Cr(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Na(1), one Cr(2), and one Si(3) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Na(2), one Cr(3), and one Si(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(2), one Cr(1), one Cr(3), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Mg(1), one Cr(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(3), one Cr(1), one Cr(3), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Ca(1), one Mg(1), one Cr(2), and one Si(4) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one Na(1), one Ca(1), one Si(1), and one Si(3) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Na(2), one Na(3), one Si(2), 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(1), one Si(1), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to one Na(2), one Na(3), one Si(2), and one Si(4) atom. is represented by the CIF card [CIF]
data_Na3CaMgCr3(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.881
_cell_length_b   5.330
_cell_length_c   9.638
_cell_angle_alpha   75.268
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   441.245
_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  0.798  0.500  0.500  1.0
  Na  Na1  1  0.303  0.000  0.000  1.0
  Na  Na2  1  0.697  0.500  0.000  1.0
  Ca  Ca3  1  0.202  0.000  0.500  1.0
  Mg  Mg4  1  0.412  0.500  0.500  1.0
  Cr  Cr5  1  0.903  0.000  0.000  1.0
  Cr  Cr6  1  0.593  0.000  0.500  1.0
  Cr  Cr7  1  0.095  0.500  0.000  1.0
  Si  Si8  1  0.090  0.691  0.289  1.0
  Si  Si9  1  0.592  0.189  0.790  1.0
  Si  Si10  1  0.090  0.309  0.711  1.0
  Si  Si11  1  0.592  0.811  0.210  1.0
  Si  Si12  1  0.906  0.808  0.710  1.0
  Si  Si13  1  0.411  0.308  0.208  1.0
  Si  Si14  1  0.906  0.192  0.290  1.0
  Si  Si15  1  0.411  0.692  0.792  1.0
  O  O16  1  0.252  0.702  0.361  1.0
  O  O17  1  0.757  0.195  0.861  1.0
  O  O18  1  0.252  0.298  0.639  1.0
  O  O19  1  0.757  0.805  0.139  1.0
  O  O20  1  0.743  0.803  0.639  1.0
  O  O21  1  0.244  0.305  0.141  1.0
  O  O22  1  0.743  0.197  0.361  1.0
  O  O23  1  0.244  0.695  0.859  1.0
  O  O24  1  0.078  0.773  0.113  1.0
  O  O25  1  0.584  0.267  0.615  1.0
  O  O26  1  0.078  0.227  0.887  1.0
  O  O27  1  0.584  0.733  0.385  1.0
  O  O28  1  0.920  0.726  0.886  1.0
  O  O29  1  0.417  0.217  0.384  1.0
  O  O30  1  0.920  0.274  0.114  1.0
  O  O31  1  0.417  0.783  0.616  1.0
  O  O32  1  0.013  0.399  0.351  1.0
  O  O33  1  0.512  0.902  0.854  1.0
  O  O34  1  0.013  0.601  0.649  1.0
  O  O35  1  0.512  0.098  0.146  1.0
  O  O36  1  0.989  0.095  0.649  1.0
  O  O37  1  0.489  0.597  0.150  1.0
  O  O38  1  0.989  0.905  0.351  1.0
  O  O39  1  0.489  0.403  0.850  1.0
[/CIF]
.
The material structure described by Na3CaMgCr3(SiO3)8 is Esseneite-derived structured and crystallizes in the monoclinic P2 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(11), two equivalent O(3), two equivalent O(6), and two equivalent O(9) atoms. In the second Na site, Na(2) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(12), two equivalent O(4), and two equivalent O(5) atoms. In the third Na site, Na(3) is bonded in a 8-coordinate geometry to two equivalent O(10), two equivalent O(12), two equivalent O(2), and two equivalent O(7) atoms. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(11), two equivalent O(8), and two equivalent O(9) atoms. Mg(1) is bonded to two equivalent O(1), two equivalent O(6), and two equivalent O(8) atoms to form MgO6 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 Cr(2)O6 octahedra. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and edges with two equivalent Cr(3)O6 octahedra. In the second Cr site, Cr(2) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(8) atoms to form CrO6 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 Mg(1)O6 octahedra. In the third Cr site, Cr(3) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms to form CrO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and edges with two equivalent Cr(1)O6 octahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(11), one O(5), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-60°. In the second Si site, Si(2) is bonded to one O(10), one O(12), one O(2), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-58°. In the third Si site, Si(3) is bonded to one O(11), one O(3), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Cr(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-60°. In the fourth Si site, Si(4) is bonded to one O(10), one O(12), one O(4), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Cr(2)O6 octahedra,  a cornercorner with one Cr(3)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-61°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Ca(1), one Mg(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Na(3), one Cr(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Na(1), one Cr(2), and one Si(3) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Na(2), one Cr(3), and one Si(4) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(2), one Cr(1), one Cr(3), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Mg(1), one Cr(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Na(3), one Cr(1), one Cr(3), and one Si(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Ca(1), one Mg(1), one Cr(2), and one Si(4) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one Na(1), one Ca(1), one Si(1), and one Si(3) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Na(2), one Na(3), one Si(2), 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(1), one Si(1), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to one Na(2), one Na(3), one Si(2), and one Si(4) atom. is represented by the CIF card [CIF]
data_Na3CaMgCr3(SiO3)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.881
_cell_length_b   5.330
_cell_length_c   9.638
_cell_angle_alpha   75.268
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   441.245
_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  0.798  0.500  0.500  1.0
  Na  Na1  1  0.303  0.000  0.000  1.0
  Na  Na2  1  0.697  0.500  0.000  1.0
  Ca  Ca3  1  0.202  0.000  0.500  1.0
  Mg  Mg4  1  0.412  0.500  0.500  1.0
  Cr  Cr5  1  0.903  0.000  0.000  1.0
  Cr  Cr6  1  0.593  0.000  0.500  1.0
  Cr  Cr7  1  0.095  0.500  0.000  1.0
  Si  Si8  1  0.090  0.691  0.289  1.0
  Si  Si9  1  0.592  0.189  0.790  1.0
  Si  Si10  1  0.090  0.309  0.711  1.0
  Si  Si11  1  0.592  0.811  0.210  1.0
  Si  Si12  1  0.906  0.808  0.710  1.0
  Si  Si13  1  0.411  0.308  0.208  1.0
  Si  Si14  1  0.906  0.192  0.290  1.0
  Si  Si15  1  0.411  0.692  0.792  1.0
  O  O16  1  0.252  0.702  0.361  1.0
  O  O17  1  0.757  0.195  0.861  1.0
  O  O18  1  0.252  0.298  0.639  1.0
  O  O19  1  0.757  0.805  0.139  1.0
  O  O20  1  0.743  0.803  0.639  1.0
  O  O21  1  0.244  0.305  0.141  1.0
  O  O22  1  0.743  0.197  0.361  1.0
  O  O23  1  0.244  0.695  0.859  1.0
  O  O24  1  0.078  0.773  0.113  1.0
  O  O25  1  0.584  0.267  0.615  1.0
  O  O26  1  0.078  0.227  0.887  1.0
  O  O27  1  0.584  0.733  0.385  1.0
  O  O28  1  0.920  0.726  0.886  1.0
  O  O29  1  0.417  0.217  0.384  1.0
  O  O30  1  0.920  0.274  0.114  1.0
  O  O31  1  0.417  0.783  0.616  1.0
  O  O32  1  0.013  0.399  0.351  1.0
  O  O33  1  0.512  0.902  0.854  1.0
  O  O34  1  0.013  0.601  0.649  1.0
  O  O35  1  0.512  0.098  0.146  1.0
  O  O36  1  0.989  0.095  0.649  1.0
  O  O37  1  0.489  0.597  0.150  1.0
  O  O38  1  0.989  0.905  0.351  1.0
  O  O39  1  0.489  0.403  0.850  1.0
[/CIF]
.