The structure described by MgFe4(PO4)4 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(2), one O(4), and two equivalent O(6) atoms to form MgO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 pentagonal pyramids, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 64°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(11), one O(12), two equivalent O(3), and two equivalent O(8) atoms to form distorted FeO6 octahedra that share corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-54°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(8) atoms to form distorted FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-54°. In the third Fe site, Fe(3) is bonded to one O(10), one O(5), two equivalent O(6), and two equivalent O(7) atoms to form distorted FeO6 pentagonal pyramids that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the fourth Fe site, Fe(4) is bonded in a 6-coordinate geometry to one O(4), one O(9), two equivalent O(6), and two equivalent O(7) atoms. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(11), one O(5), and two equivalent O(6) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(3)O6 pentagonal pyramid, corners with two equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Fe(3)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles are 35°. In the second P site, P(2) is bonded to one O(1), one O(9), and two equivalent O(7) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra and corners with two equivalent Fe(3)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 51°. In the third P site, P(3) is bonded to one O(10), one O(12), and two equivalent O(8) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 pentagonal pyramid, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-58°. In the fourth P site, P(4) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-58°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Fe(2) and one P(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mg(1), one Fe(2), and one P(4) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(4), and one P(4) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(3), one Fe(4), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Fe(3), one Fe(4), and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Fe(4) and one P(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(3) atom. is represented by the CIF file [CIF]
data_MgFe4(PO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.082
_cell_length_b   5.932
_cell_length_c   5.039
_cell_angle_alpha   90.001
_cell_angle_beta   88.899
_cell_angle_gamma   89.999
_symmetry_Int_Tables_number   1
_cell_volume   301.291
_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
  Mg  Mg0  1  0.067  0.750  0.071  1.0
  Fe  Fe1  1  0.766  0.250  0.543  1.0
  Fe  Fe2  1  0.717  0.750  0.063  1.0
  Fe  Fe3  1  0.283  0.250  0.938  1.0
  Fe  Fe4  1  0.245  0.750  0.489  1.0
  P  P5  1  0.090  0.250  0.378  1.0
  P  P6  1  0.409  0.750  0.921  1.0
  P  P7  1  0.596  0.250  0.110  1.0
  P  P8  1  0.902  0.750  0.594  1.0
  O  O9  1  0.553  0.750  0.837  1.0
  O  O10  1  0.902  0.750  0.287  1.0
  O  O11  1  0.832  0.957  0.721  1.0
  O  O12  1  0.832  0.543  0.721  1.0
  O  O13  1  0.051  0.750  0.681  1.0
  O  O14  1  0.136  0.250  0.664  1.0
  O  O15  1  0.154  0.043  0.217  1.0
  O  O16  1  0.154  0.457  0.217  1.0
  O  O17  1  0.330  0.547  0.786  1.0
  O  O18  1  0.665  0.450  0.259  1.0
  O  O19  1  0.383  0.750  0.219  1.0
  O  O20  1  0.444  0.250  0.152  1.0
  O  O21  1  0.941  0.250  0.347  1.0
  O  O22  1  0.628  0.250  0.812  1.0
  O  O23  1  0.665  0.050  0.259  1.0
  O  O24  1  0.330  0.953  0.786  1.0
[/CIF]
.
The structure described by MgFe4(PO4)4 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(2), one O(4), and two equivalent O(6) atoms to form MgO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 pentagonal pyramids, corners with two equivalent P(1)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 64°. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(11), one O(12), two equivalent O(3), and two equivalent O(8) atoms to form distorted FeO6 octahedra that share corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(4)O4 tetrahedra, and  an edgeedge with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-54°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(8) atoms to form distorted FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one P(2)O4 tetrahedra,  a cornercorner with one P(4)O4 tetrahedra, corners with two equivalent P(3)O4 tetrahedra, and  an edgeedge with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-54°. In the third Fe site, Fe(3) is bonded to one O(10), one O(5), two equivalent O(6), and two equivalent O(7) atoms to form distorted FeO6 pentagonal pyramids that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. In the fourth Fe site, Fe(4) is bonded in a 6-coordinate geometry to one O(4), one O(9), two equivalent O(6), and two equivalent O(7) atoms. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(11), one O(5), and two equivalent O(6) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Fe(3)O6 pentagonal pyramid, corners with two equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Fe(3)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles are 35°. In the second P site, P(2) is bonded to one O(1), one O(9), and two equivalent O(7) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra and corners with two equivalent Fe(3)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 51°. In the third P site, P(3) is bonded to one O(10), one O(12), and two equivalent O(8) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O6 pentagonal pyramid, and  an edgeedge with one Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 34-58°. In the fourth P site, P(4) is bonded to one O(2), one O(4), and two equivalent O(3) atoms to form PO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, and  an edgeedge with one Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-58°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Fe(2) and one P(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mg(1), one Fe(2), and one P(4) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Fe(1), one Fe(2), and one P(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1), one Fe(4), and one P(4) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(3), one Fe(4), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Fe(3), one Fe(4), and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(3) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Fe(4) and one P(2) atom. In the tenth O site, O(10) is bonded in a bent 150 degrees geometry to one Fe(3) and one P(3) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(3) atom. is represented by the CIF file [CIF]
data_MgFe4(PO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.082
_cell_length_b   5.932
_cell_length_c   5.039
_cell_angle_alpha   90.001
_cell_angle_beta   88.899
_cell_angle_gamma   89.999
_symmetry_Int_Tables_number   1
_cell_volume   301.291
_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
  Mg  Mg0  1  0.067  0.750  0.071  1.0
  Fe  Fe1  1  0.766  0.250  0.543  1.0
  Fe  Fe2  1  0.717  0.750  0.063  1.0
  Fe  Fe3  1  0.283  0.250  0.938  1.0
  Fe  Fe4  1  0.245  0.750  0.489  1.0
  P  P5  1  0.090  0.250  0.378  1.0
  P  P6  1  0.409  0.750  0.921  1.0
  P  P7  1  0.596  0.250  0.110  1.0
  P  P8  1  0.902  0.750  0.594  1.0
  O  O9  1  0.553  0.750  0.837  1.0
  O  O10  1  0.902  0.750  0.287  1.0
  O  O11  1  0.832  0.957  0.721  1.0
  O  O12  1  0.832  0.543  0.721  1.0
  O  O13  1  0.051  0.750  0.681  1.0
  O  O14  1  0.136  0.250  0.664  1.0
  O  O15  1  0.154  0.043  0.217  1.0
  O  O16  1  0.154  0.457  0.217  1.0
  O  O17  1  0.330  0.547  0.786  1.0
  O  O18  1  0.665  0.450  0.259  1.0
  O  O19  1  0.383  0.750  0.219  1.0
  O  O20  1  0.444  0.250  0.152  1.0
  O  O21  1  0.941  0.250  0.347  1.0
  O  O22  1  0.628  0.250  0.812  1.0
  O  O23  1  0.665  0.050  0.259  1.0
  O  O24  1  0.330  0.953  0.786  1.0
[/CIF]
.