The crystal structure described by Mg3Fe4O7 is Caswellsilverite-like structured and crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Fe(1)O6 octahedra, and edges with five equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the second Mg site, Mg(2) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with eight equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, edges with three equivalent Fe(1)O6 octahedra, edges with four equivalent Mg(1)O6 octahedra, and edges with four equivalent Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. In the second Fe site, Fe(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra, edges with five equivalent Mg(1)O6 octahedra, and edges with six equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(2) and four equivalent Fe(1) atoms to form OMg2Fe4 octahedra that share corners with two equivalent O(1)Mg2Fe4 octahedra, corners with four equivalent O(2)Mg2Fe4 octahedra, edges with two equivalent O(1)Mg2Fe4 octahedra, edges with two equivalent O(2)Mg2Fe4 octahedra, and edges with eight equivalent O(4)Mg4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the second O site, O(2) is bonded to two equivalent Mg(1), two equivalent Fe(1), and two equivalent Fe(2) atoms to form OMg2Fe4 octahedra that share corners with two equivalent O(1)Mg2Fe4 octahedra, corners with two equivalent O(2)Mg2Fe4 octahedra, corners with two equivalent O(3)Mg2Fe4 octahedra,  an edgeedge with one O(1)Mg2Fe4 octahedra, edges with two equivalent O(2)Mg2Fe4 octahedra, edges with four equivalent O(4)Mg4Fe2 octahedra, and edges with five equivalent O(3)Mg2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the third O site, O(3) is bonded to two equivalent Mg(1) and four equivalent Fe(2) atoms to form OMg2Fe4 octahedra that share corners with two equivalent O(2)Mg2Fe4 octahedra, corners with two equivalent O(3)Mg2Fe4 octahedra, corners with two equivalent O(4)Mg4Fe2 octahedra,  an edgeedge with one O(4)Mg4Fe2 octahedra, edges with five equivalent O(2)Mg2Fe4 octahedra, and edges with six equivalent O(3)Mg2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the fourth O site, O(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Fe(1) atoms to form OMg4Fe2 octahedra that share corners with two equivalent O(3)Mg2Fe4 octahedra, corners with four equivalent O(4)Mg4Fe2 octahedra,  an edgeedge with one O(3)Mg2Fe4 octahedra, edges with three equivalent O(4)Mg4Fe2 octahedra, edges with four equivalent O(1)Mg2Fe4 octahedra, and edges with four equivalent O(2)Mg2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg3Fe4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.046
_cell_length_b   11.046
_cell_length_c   11.046
_cell_angle_alpha   164.086
_cell_angle_beta   157.312
_cell_angle_gamma   27.836
_symmetry_Int_Tables_number   1
_cell_volume   142.481
_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  0.642  0.638  0.996  1.0
  Mg  Mg1  1  0.500  0.502  0.002  1.0
  Mg  Mg2  1  0.358  0.355  0.996  1.0
  Fe  Fe3  1  0.927  0.928  0.000  1.0
  Fe  Fe4  1  0.073  0.073  0.000  1.0
  Fe  Fe5  1  0.783  0.795  0.011  1.0
  Fe  Fe6  1  0.217  0.228  0.011  1.0
  O  O7  1  0.000  0.486  0.486  1.0
  O  O8  1  0.855  0.375  0.520  1.0
  O  O9  1  0.710  0.197  0.487  1.0
  O  O10  1  0.429  0.929  0.500  1.0
  O  O11  1  0.571  0.072  0.500  1.0
  O  O12  1  0.145  0.665  0.520  1.0
  O  O13  1  0.290  0.777  0.487  1.0
[/CIF]
.
The crystal structure described by Mg3Fe4O7 is Caswellsilverite-like structured and crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Mg(2)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with four equivalent Fe(1)O6 octahedra, and edges with five equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the second Mg site, Mg(2) is bonded to two equivalent O(1) and four equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Mg(2)O6 octahedra, corners with four equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and edges with eight equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent Fe(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, edges with three equivalent Fe(1)O6 octahedra, edges with four equivalent Mg(1)O6 octahedra, and edges with four equivalent Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 1-2°. In the second Fe site, Fe(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form FeO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  an edgeedge with one Fe(1)O6 octahedra, edges with five equivalent Mg(1)O6 octahedra, and edges with six equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(2) and four equivalent Fe(1) atoms to form OMg2Fe4 octahedra that share corners with two equivalent O(1)Mg2Fe4 octahedra, corners with four equivalent O(2)Mg2Fe4 octahedra, edges with two equivalent O(1)Mg2Fe4 octahedra, edges with two equivalent O(2)Mg2Fe4 octahedra, and edges with eight equivalent O(4)Mg4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-3°. In the second O site, O(2) is bonded to two equivalent Mg(1), two equivalent Fe(1), and two equivalent Fe(2) atoms to form OMg2Fe4 octahedra that share corners with two equivalent O(1)Mg2Fe4 octahedra, corners with two equivalent O(2)Mg2Fe4 octahedra, corners with two equivalent O(3)Mg2Fe4 octahedra,  an edgeedge with one O(1)Mg2Fe4 octahedra, edges with two equivalent O(2)Mg2Fe4 octahedra, edges with four equivalent O(4)Mg4Fe2 octahedra, and edges with five equivalent O(3)Mg2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the third O site, O(3) is bonded to two equivalent Mg(1) and four equivalent Fe(2) atoms to form OMg2Fe4 octahedra that share corners with two equivalent O(2)Mg2Fe4 octahedra, corners with two equivalent O(3)Mg2Fe4 octahedra, corners with two equivalent O(4)Mg4Fe2 octahedra,  an edgeedge with one O(4)Mg4Fe2 octahedra, edges with five equivalent O(2)Mg2Fe4 octahedra, and edges with six equivalent O(3)Mg2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the fourth O site, O(4) is bonded to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Fe(1) atoms to form OMg4Fe2 octahedra that share corners with two equivalent O(3)Mg2Fe4 octahedra, corners with four equivalent O(4)Mg4Fe2 octahedra,  an edgeedge with one O(3)Mg2Fe4 octahedra, edges with three equivalent O(4)Mg4Fe2 octahedra, edges with four equivalent O(1)Mg2Fe4 octahedra, and edges with four equivalent O(2)Mg2Fe4 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg3Fe4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.046
_cell_length_b   11.046
_cell_length_c   11.046
_cell_angle_alpha   164.086
_cell_angle_beta   157.312
_cell_angle_gamma   27.836
_symmetry_Int_Tables_number   1
_cell_volume   142.481
_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  0.642  0.638  0.996  1.0
  Mg  Mg1  1  0.500  0.502  0.002  1.0
  Mg  Mg2  1  0.358  0.355  0.996  1.0
  Fe  Fe3  1  0.927  0.928  0.000  1.0
  Fe  Fe4  1  0.073  0.073  0.000  1.0
  Fe  Fe5  1  0.783  0.795  0.011  1.0
  Fe  Fe6  1  0.217  0.228  0.011  1.0
  O  O7  1  0.000  0.486  0.486  1.0
  O  O8  1  0.855  0.375  0.520  1.0
  O  O9  1  0.710  0.197  0.487  1.0
  O  O10  1  0.429  0.929  0.500  1.0
  O  O11  1  0.571  0.072  0.500  1.0
  O  O12  1  0.145  0.665  0.520  1.0
  O  O13  1  0.290  0.777  0.487  1.0
[/CIF]
.