The compound described by MgCr3(FeO4)2 is Spinel-derived structured and crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form MgO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, and corners with six equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-59°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form CrO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Cr(2)O6 octahedra. In the second Cr site, Cr(2) 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 CrO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), one O(5), and two equivalent O(6) atoms to form FeO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, and corners with six equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-60°. In the second Fe site, Fe(2) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Cr(1)O6 octahedra, and edges with four equivalent Cr(2)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Cr(1), one Cr(2), and one Fe(2) atom to form distorted OMgCr2Fe trigonal pyramids that share  a cornercorner with one O(1)MgCr2Fe trigonal pyramid,  a cornercorner with one O(2)MgCr2Fe trigonal pyramid,  a cornercorner with one O(3)MgCr3 trigonal pyramid, corners with two equivalent O(5)Cr2Fe2 trigonal pyramids, corners with two equivalent O(4)Cr3Fe trigonal pyramids, corners with five equivalent O(6)Cr2Fe2 trigonal pyramids,  an edgeedge with one O(1)MgCr2Fe trigonal pyramid,  an edgeedge with one O(2)MgCr2Fe trigonal pyramid, and  an edgeedge with one O(3)MgCr3 trigonal pyramid. In the second O site, O(2) is bonded to one Mg(1), two equivalent Cr(2), and one Fe(2) atom to form distorted OMgCr2Fe trigonal pyramids that share  a cornercorner with one O(3)MgCr3 trigonal pyramid, corners with two equivalent O(4)Cr3Fe trigonal pyramids, corners with two equivalent O(1)MgCr2Fe trigonal pyramids, corners with three equivalent O(5)Cr2Fe2 trigonal pyramids, corners with four equivalent O(6)Cr2Fe2 trigonal pyramids,  an edgeedge with one O(3)MgCr3 trigonal pyramid, and edges with two equivalent O(1)MgCr2Fe trigonal pyramids. In the third O site, O(3) is bonded to one Mg(1), one Cr(1), and two equivalent Cr(2) atoms to form distorted OMgCr3 trigonal pyramids that share  a cornercorner with one O(2)MgCr2Fe trigonal pyramid, corners with two equivalent O(5)Cr2Fe2 trigonal pyramids, corners with two equivalent O(1)MgCr2Fe trigonal pyramids, corners with three equivalent O(4)Cr3Fe trigonal pyramids, corners with four equivalent O(6)Cr2Fe2 trigonal pyramids,  an edgeedge with one O(2)MgCr2Fe trigonal pyramid, and edges with two equivalent O(1)MgCr2Fe trigonal pyramids. In the fourth O site, O(4) is bonded to one Cr(1), two equivalent Cr(2), and one Fe(1) atom to form distorted OCr3Fe trigonal pyramids that share  a cornercorner with one O(5)Cr2Fe2 trigonal pyramid, corners with two equivalent O(6)Cr2Fe2 trigonal pyramids, corners with two equivalent O(2)MgCr2Fe trigonal pyramids, corners with three equivalent O(3)MgCr3 trigonal pyramids, corners with four equivalent O(1)MgCr2Fe trigonal pyramids,  an edgeedge with one O(5)Cr2Fe2 trigonal pyramid, and edges with two equivalent O(6)Cr2Fe2 trigonal pyramids. In the fifth O site, O(5) is bonded to two equivalent Cr(2), one Fe(1), and one Fe(2) atom to form distorted OCr2Fe2 trigonal pyramids that share  a cornercorner with one O(4)Cr3Fe trigonal pyramid, corners with two equivalent O(6)Cr2Fe2 trigonal pyramids, corners with two equivalent O(3)MgCr3 trigonal pyramids, corners with three equivalent O(2)MgCr2Fe trigonal pyramids, corners with four equivalent O(1)MgCr2Fe trigonal pyramids,  an edgeedge with one O(4)Cr3Fe trigonal pyramid, and edges with two equivalent O(6)Cr2Fe2 trigonal pyramids. In the sixth O site, O(6) is bonded to one Cr(1), one Cr(2), one Fe(1), and one Fe(2) atom to form distorted OCr2Fe2 trigonal pyramids that share  a cornercorner with one O(5)Cr2Fe2 trigonal pyramid,  a cornercorner with one O(6)Cr2Fe2 trigonal pyramid,  a cornercorner with one O(4)Cr3Fe trigonal pyramid, corners with two equivalent O(2)MgCr2Fe trigonal pyramids, corners with two equivalent O(3)MgCr3 trigonal pyramids, corners with five equivalent O(1)MgCr2Fe trigonal pyramids,  an edgeedge with one O(5)Cr2Fe2 trigonal pyramid,  an edgeedge with one O(6)Cr2Fe2 trigonal pyramid, and  an edgeedge with one O(4)Cr3Fe trigonal pyramid. is represented by the CIF file [CIF]
data_MgCr3(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.032
_cell_length_b   6.057
_cell_length_c   6.044
_cell_angle_alpha   59.688
_cell_angle_beta   60.065
_cell_angle_gamma   60.135
_symmetry_Int_Tables_number   1
_cell_volume   155.997
_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  0.250  0.250  0.251  1.0
  Cr  Cr1  1  0.625  0.125  0.625  1.0
  Cr  Cr2  1  0.126  0.625  0.625  1.0
  Cr  Cr3  1  0.625  0.625  0.625  1.0
  Fe  Fe4  1  0.001  0.002  0.997  1.0
  Fe  Fe5  1  0.624  0.624  0.128  1.0
  O  O6  1  0.842  0.385  0.388  1.0
  O  O7  1  0.384  0.385  0.388  1.0
  O  O8  1  0.386  0.842  0.386  1.0
  O  O9  1  0.387  0.385  0.841  1.0
  O  O10  1  0.861  0.865  0.413  1.0
  O  O11  1  0.862  0.413  0.863  1.0
  O  O12  1  0.413  0.862  0.860  1.0
  O  O13  1  0.866  0.862  0.860  1.0
[/CIF]
.
The compound described by MgCr3(FeO4)2 is Spinel-derived structured and crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form MgO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, and corners with six equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-59°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(6) atoms to form CrO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Cr(2)O6 octahedra. In the second Cr site, Cr(2) 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 CrO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Cr(1)O6 octahedra, edges with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4), one O(5), and two equivalent O(6) atoms to form FeO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra, corners with three equivalent Fe(2)O6 octahedra, and corners with six equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-60°. In the second Fe site, Fe(2) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with three equivalent Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Cr(1)O6 octahedra, and edges with four equivalent Cr(2)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Cr(1), one Cr(2), and one Fe(2) atom to form distorted OMgCr2Fe trigonal pyramids that share  a cornercorner with one O(1)MgCr2Fe trigonal pyramid,  a cornercorner with one O(2)MgCr2Fe trigonal pyramid,  a cornercorner with one O(3)MgCr3 trigonal pyramid, corners with two equivalent O(5)Cr2Fe2 trigonal pyramids, corners with two equivalent O(4)Cr3Fe trigonal pyramids, corners with five equivalent O(6)Cr2Fe2 trigonal pyramids,  an edgeedge with one O(1)MgCr2Fe trigonal pyramid,  an edgeedge with one O(2)MgCr2Fe trigonal pyramid, and  an edgeedge with one O(3)MgCr3 trigonal pyramid. In the second O site, O(2) is bonded to one Mg(1), two equivalent Cr(2), and one Fe(2) atom to form distorted OMgCr2Fe trigonal pyramids that share  a cornercorner with one O(3)MgCr3 trigonal pyramid, corners with two equivalent O(4)Cr3Fe trigonal pyramids, corners with two equivalent O(1)MgCr2Fe trigonal pyramids, corners with three equivalent O(5)Cr2Fe2 trigonal pyramids, corners with four equivalent O(6)Cr2Fe2 trigonal pyramids,  an edgeedge with one O(3)MgCr3 trigonal pyramid, and edges with two equivalent O(1)MgCr2Fe trigonal pyramids. In the third O site, O(3) is bonded to one Mg(1), one Cr(1), and two equivalent Cr(2) atoms to form distorted OMgCr3 trigonal pyramids that share  a cornercorner with one O(2)MgCr2Fe trigonal pyramid, corners with two equivalent O(5)Cr2Fe2 trigonal pyramids, corners with two equivalent O(1)MgCr2Fe trigonal pyramids, corners with three equivalent O(4)Cr3Fe trigonal pyramids, corners with four equivalent O(6)Cr2Fe2 trigonal pyramids,  an edgeedge with one O(2)MgCr2Fe trigonal pyramid, and edges with two equivalent O(1)MgCr2Fe trigonal pyramids. In the fourth O site, O(4) is bonded to one Cr(1), two equivalent Cr(2), and one Fe(1) atom to form distorted OCr3Fe trigonal pyramids that share  a cornercorner with one O(5)Cr2Fe2 trigonal pyramid, corners with two equivalent O(6)Cr2Fe2 trigonal pyramids, corners with two equivalent O(2)MgCr2Fe trigonal pyramids, corners with three equivalent O(3)MgCr3 trigonal pyramids, corners with four equivalent O(1)MgCr2Fe trigonal pyramids,  an edgeedge with one O(5)Cr2Fe2 trigonal pyramid, and edges with two equivalent O(6)Cr2Fe2 trigonal pyramids. In the fifth O site, O(5) is bonded to two equivalent Cr(2), one Fe(1), and one Fe(2) atom to form distorted OCr2Fe2 trigonal pyramids that share  a cornercorner with one O(4)Cr3Fe trigonal pyramid, corners with two equivalent O(6)Cr2Fe2 trigonal pyramids, corners with two equivalent O(3)MgCr3 trigonal pyramids, corners with three equivalent O(2)MgCr2Fe trigonal pyramids, corners with four equivalent O(1)MgCr2Fe trigonal pyramids,  an edgeedge with one O(4)Cr3Fe trigonal pyramid, and edges with two equivalent O(6)Cr2Fe2 trigonal pyramids. In the sixth O site, O(6) is bonded to one Cr(1), one Cr(2), one Fe(1), and one Fe(2) atom to form distorted OCr2Fe2 trigonal pyramids that share  a cornercorner with one O(5)Cr2Fe2 trigonal pyramid,  a cornercorner with one O(6)Cr2Fe2 trigonal pyramid,  a cornercorner with one O(4)Cr3Fe trigonal pyramid, corners with two equivalent O(2)MgCr2Fe trigonal pyramids, corners with two equivalent O(3)MgCr3 trigonal pyramids, corners with five equivalent O(1)MgCr2Fe trigonal pyramids,  an edgeedge with one O(5)Cr2Fe2 trigonal pyramid,  an edgeedge with one O(6)Cr2Fe2 trigonal pyramid, and  an edgeedge with one O(4)Cr3Fe trigonal pyramid. is represented by the CIF file [CIF]
data_MgCr3(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.032
_cell_length_b   6.057
_cell_length_c   6.044
_cell_angle_alpha   59.688
_cell_angle_beta   60.065
_cell_angle_gamma   60.135
_symmetry_Int_Tables_number   1
_cell_volume   155.997
_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  0.250  0.250  0.251  1.0
  Cr  Cr1  1  0.625  0.125  0.625  1.0
  Cr  Cr2  1  0.126  0.625  0.625  1.0
  Cr  Cr3  1  0.625  0.625  0.625  1.0
  Fe  Fe4  1  0.001  0.002  0.997  1.0
  Fe  Fe5  1  0.624  0.624  0.128  1.0
  O  O6  1  0.842  0.385  0.388  1.0
  O  O7  1  0.384  0.385  0.388  1.0
  O  O8  1  0.386  0.842  0.386  1.0
  O  O9  1  0.387  0.385  0.841  1.0
  O  O10  1  0.861  0.865  0.413  1.0
  O  O11  1  0.862  0.413  0.863  1.0
  O  O12  1  0.413  0.862  0.860  1.0
  O  O13  1  0.866  0.862  0.860  1.0
[/CIF]
.