The crystal structure described by MgCr2(FeO4)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(1), one O(5), and two equivalent O(4) atoms to form MgO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra, corners with two equivalent Cr(2)O4 tetrahedra, and  an edgeedge with one Cr(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 63-66°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form CrO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-59°. In the second Cr site, Cr(2) is bonded to one O(2), one O(6), and two equivalent O(4) atoms to form CrO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-55°. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Cr(1)O4 tetrahedra, corners with three equivalent Cr(2)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Cr(1), and two equivalent Fe(1) atoms to form distorted edge-sharing OMgCrFe2 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cr(2) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Cr(1) and one Fe(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1), one Cr(2), and one Fe(1) atom. In the fifth O site, O(5) is bonded to one Mg(1), one Cr(1), and two equivalent Fe(1) atoms to form distorted edge-sharing OMgCrFe2 tetrahedra. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Cr(2) and two equivalent Fe(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgCr2(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.124
_cell_length_b   5.105
_cell_length_c   6.147
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   65.451
_symmetry_Int_Tables_number   1
_cell_volume   146.270
_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  0.661  0.669  0.250  1.0
  Cr  Cr1  1  0.335  0.340  0.250  1.0
  Cr  Cr2  1  0.647  0.643  0.750  1.0
  Fe  Fe3  1  0.003  0.002  0.996  1.0
  Fe  Fe4  1  0.003  0.002  0.504  1.0
  O  O5  1  0.231  0.747  0.250  1.0
  O  O6  1  0.262  0.784  0.750  1.0
  O  O7  1  0.220  0.219  0.024  1.0
  O  O8  1  0.220  0.219  0.476  1.0
  O  O9  1  0.781  0.779  0.523  1.0
  O  O10  1  0.781  0.779  0.977  1.0
  O  O11  1  0.737  0.240  0.250  1.0
  O  O12  1  0.796  0.252  0.750  1.0
[/CIF]
.
The crystal structure described by MgCr2(FeO4)2 crystallizes in the monoclinic Pm space group. Mg(1) is bonded to one O(1), one O(5), and two equivalent O(4) atoms to form MgO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra, corners with two equivalent Cr(2)O4 tetrahedra, and  an edgeedge with one Cr(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 63-66°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form CrO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and  an edgeedge with one Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 49-59°. In the second Cr site, Cr(2) is bonded to one O(2), one O(6), and two equivalent O(4) atoms to form CrO4 tetrahedra that share corners with six equivalent Fe(1)O6 octahedra and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-55°. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form FeO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Cr(1)O4 tetrahedra, corners with three equivalent Cr(2)O4 tetrahedra, and edges with two equivalent Fe(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Cr(1), and two equivalent Fe(1) atoms to form distorted edge-sharing OMgCrFe2 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cr(2) and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Cr(1) and one Fe(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(1), one Cr(2), and one Fe(1) atom. In the fifth O site, O(5) is bonded to one Mg(1), one Cr(1), and two equivalent Fe(1) atoms to form distorted edge-sharing OMgCrFe2 tetrahedra. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Cr(2) and two equivalent Fe(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgCr2(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.124
_cell_length_b   5.105
_cell_length_c   6.147
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   65.451
_symmetry_Int_Tables_number   1
_cell_volume   146.270
_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  0.661  0.669  0.250  1.0
  Cr  Cr1  1  0.335  0.340  0.250  1.0
  Cr  Cr2  1  0.647  0.643  0.750  1.0
  Fe  Fe3  1  0.003  0.002  0.996  1.0
  Fe  Fe4  1  0.003  0.002  0.504  1.0
  O  O5  1  0.231  0.747  0.250  1.0
  O  O6  1  0.262  0.784  0.750  1.0
  O  O7  1  0.220  0.219  0.024  1.0
  O  O8  1  0.220  0.219  0.476  1.0
  O  O9  1  0.781  0.779  0.523  1.0
  O  O10  1  0.781  0.779  0.977  1.0
  O  O11  1  0.737  0.240  0.250  1.0
  O  O12  1  0.796  0.252  0.750  1.0
[/CIF]
.