The material described by Na2MgFe2(PO4)3 is Esseneite-derived structured and crystallizes in the monoclinic C2/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(3), two equivalent O(6), and four equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form distorted MgO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. Fe(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-59°. In the second P site, P(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-58°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Fe(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(2), one Mg(1), and one P(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Mg(1), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Fe(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(1), one Mg(1), one Fe(1), and one P(2) atom. is represented by the CIF card [CIF]
data_Na2MgFe2(PO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.678
_cell_length_b   8.678
_cell_length_c   6.571
_cell_angle_alpha   73.779
_cell_angle_beta   73.779
_cell_angle_gamma   93.290
_symmetry_Int_Tables_number   1
_cell_volume   451.272
_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  0.984  0.016  0.250  1.0
  Na  Na1  1  0.016  0.984  0.750  1.0
  Na  Na2  1  0.500  0.500  0.000  1.0
  Na  Na3  1  0.500  0.500  0.500  1.0
  Mg  Mg4  1  0.267  0.733  0.250  1.0
  Mg  Mg5  1  0.733  0.267  0.750  1.0
  Fe  Fe6  1  0.381  0.057  0.374  1.0
  Fe  Fe7  1  0.619  0.943  0.626  1.0
  Fe  Fe8  1  0.943  0.619  0.126  1.0
  Fe  Fe9  1  0.057  0.381  0.874  1.0
  P  P10  1  0.711  0.289  0.250  1.0
  P  P11  1  0.289  0.711  0.750  1.0
  P  P12  1  0.655  0.874  0.120  1.0
  P  P13  1  0.345  0.126  0.880  1.0
  P  P14  1  0.126  0.345  0.380  1.0
  P  P15  1  0.874  0.655  0.620  1.0
  O  O16  1  0.533  0.262  0.254  1.0
  O  O17  1  0.467  0.738  0.746  1.0
  O  O18  1  0.738  0.467  0.246  1.0
  O  O19  1  0.262  0.533  0.754  1.0
  O  O20  1  0.522  0.731  0.171  1.0
  O  O21  1  0.478  0.269  0.829  1.0
  O  O22  1  0.269  0.478  0.329  1.0
  O  O23  1  0.731  0.522  0.671  1.0
  O  O24  1  0.742  0.178  0.464  1.0
  O  O25  1  0.258  0.822  0.536  1.0
  O  O26  1  0.822  0.258  0.036  1.0
  O  O27  1  0.178  0.742  0.964  1.0
  O  O28  1  0.603  0.956  0.309  1.0
  O  O29  1  0.397  0.044  0.691  1.0
  O  O30  1  0.044  0.397  0.191  1.0
  O  O31  1  0.956  0.603  0.809  1.0
  O  O32  1  0.826  0.825  0.110  1.0
  O  O33  1  0.174  0.175  0.890  1.0
  O  O34  1  0.175  0.174  0.390  1.0
  O  O35  1  0.825  0.826  0.610  1.0
  O  O36  1  0.324  0.995  0.110  1.0
  O  O37  1  0.676  0.005  0.890  1.0
  O  O38  1  0.005  0.676  0.390  1.0
  O  O39  1  0.995  0.324  0.610  1.0
[/CIF]
.
The material described by Na2MgFe2(PO4)3 is Esseneite-derived structured and crystallizes in the monoclinic C2/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 8-coordinate geometry to two equivalent O(3), two equivalent O(6), and four equivalent O(5) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(1) and four equivalent O(2) atoms. Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form distorted MgO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. Fe(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with four equivalent P(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one Fe(1)O6 octahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(1) and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-59°. In the second P site, P(2) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-58°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(2), one Fe(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(2), one Mg(1), and one P(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Mg(1), one Fe(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Fe(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Fe(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Na(1), one Mg(1), one Fe(1), and one P(2) atom. is represented by the CIF card [CIF]
data_Na2MgFe2(PO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.678
_cell_length_b   8.678
_cell_length_c   6.571
_cell_angle_alpha   73.779
_cell_angle_beta   73.779
_cell_angle_gamma   93.290
_symmetry_Int_Tables_number   1
_cell_volume   451.272
_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  0.984  0.016  0.250  1.0
  Na  Na1  1  0.016  0.984  0.750  1.0
  Na  Na2  1  0.500  0.500  0.000  1.0
  Na  Na3  1  0.500  0.500  0.500  1.0
  Mg  Mg4  1  0.267  0.733  0.250  1.0
  Mg  Mg5  1  0.733  0.267  0.750  1.0
  Fe  Fe6  1  0.381  0.057  0.374  1.0
  Fe  Fe7  1  0.619  0.943  0.626  1.0
  Fe  Fe8  1  0.943  0.619  0.126  1.0
  Fe  Fe9  1  0.057  0.381  0.874  1.0
  P  P10  1  0.711  0.289  0.250  1.0
  P  P11  1  0.289  0.711  0.750  1.0
  P  P12  1  0.655  0.874  0.120  1.0
  P  P13  1  0.345  0.126  0.880  1.0
  P  P14  1  0.126  0.345  0.380  1.0
  P  P15  1  0.874  0.655  0.620  1.0
  O  O16  1  0.533  0.262  0.254  1.0
  O  O17  1  0.467  0.738  0.746  1.0
  O  O18  1  0.738  0.467  0.246  1.0
  O  O19  1  0.262  0.533  0.754  1.0
  O  O20  1  0.522  0.731  0.171  1.0
  O  O21  1  0.478  0.269  0.829  1.0
  O  O22  1  0.269  0.478  0.329  1.0
  O  O23  1  0.731  0.522  0.671  1.0
  O  O24  1  0.742  0.178  0.464  1.0
  O  O25  1  0.258  0.822  0.536  1.0
  O  O26  1  0.822  0.258  0.036  1.0
  O  O27  1  0.178  0.742  0.964  1.0
  O  O28  1  0.603  0.956  0.309  1.0
  O  O29  1  0.397  0.044  0.691  1.0
  O  O30  1  0.044  0.397  0.191  1.0
  O  O31  1  0.956  0.603  0.809  1.0
  O  O32  1  0.826  0.825  0.110  1.0
  O  O33  1  0.174  0.175  0.890  1.0
  O  O34  1  0.175  0.174  0.390  1.0
  O  O35  1  0.825  0.826  0.610  1.0
  O  O36  1  0.324  0.995  0.110  1.0
  O  O37  1  0.676  0.005  0.890  1.0
  O  O38  1  0.005  0.676  0.390  1.0
  O  O39  1  0.995  0.324  0.610  1.0
[/CIF]
.