The structure described by MgCrO4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Cr(1)O4 tetrahedra, corners with four equivalent Cr(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Mg(2)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Cr(2)O4 tetrahedra, corners with four equivalent Cr(1)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form CrO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 19-55°. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form CrO4 tetrahedra that share corners with two equivalent Mg(2)O6 octahedra and corners with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 15-63°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Mg(2), two equivalent Mg(1), and one Cr(2) atom to form distorted edge-sharing OMg3Cr tetrahedra. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(2) and one Cr(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(2) and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Cr(1) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Mg(1) and one Cr(2) atom. is represented by the CIF card [CIF]
data_MgCrO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.844
_cell_length_b   6.844
_cell_length_c   6.842
_cell_angle_alpha   79.912
_cell_angle_beta   79.912
_cell_angle_gamma   85.332
_symmetry_Int_Tables_number   1
_cell_volume   310.206
_cell_formula_units_Z   4
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  0.818  0.182  0.500  1.0
  Mg  Mg1  1  0.182  0.818  0.500  1.0
  Mg  Mg2  1  0.203  0.203  0.134  1.0
  Mg  Mg3  1  0.797  0.797  0.866  1.0
  Cr  Cr4  1  0.744  0.256  0.000  1.0
  Cr  Cr5  1  0.256  0.744  0.000  1.0
  Cr  Cr6  1  0.726  0.726  0.412  1.0
  Cr  Cr7  1  0.274  0.274  0.588  1.0
  O  O8  1  0.142  0.142  0.460  1.0
  O  O9  1  0.858  0.858  0.540  1.0
  O  O10  1  0.788  0.788  0.168  1.0
  O  O11  1  0.212  0.212  0.832  1.0
  O  O12  1  0.512  0.221  0.103  1.0
  O  O13  1  0.779  0.488  0.897  1.0
  O  O14  1  0.488  0.779  0.897  1.0
  O  O15  1  0.221  0.512  0.103  1.0
  O  O16  1  0.201  0.888  0.184  1.0
  O  O17  1  0.112  0.799  0.816  1.0
  O  O18  1  0.799  0.112  0.816  1.0
  O  O19  1  0.888  0.201  0.184  1.0
  O  O20  1  0.489  0.784  0.477  1.0
  O  O21  1  0.216  0.511  0.523  1.0
  O  O22  1  0.511  0.216  0.523  1.0
  O  O23  1  0.784  0.489  0.477  1.0
[/CIF]
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The structure described by MgCrO4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form MgO6 octahedra that share corners with two equivalent Cr(1)O4 tetrahedra, corners with four equivalent Cr(2)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra, and edges with two equivalent Mg(2)O6 octahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with two equivalent Cr(2)O4 tetrahedra, corners with four equivalent Cr(1)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form CrO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with four equivalent Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 19-55°. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form CrO4 tetrahedra that share corners with two equivalent Mg(2)O6 octahedra and corners with four equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 15-63°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Mg(2), two equivalent Mg(1), and one Cr(2) atom to form distorted edge-sharing OMg3Cr tetrahedra. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mg(2) and one Cr(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Mg(2) and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Cr(1) atom. In the fifth O site, O(5) is bonded in a linear geometry to one Mg(1) and one Cr(2) atom. is represented by the CIF card [CIF]
data_MgCrO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.844
_cell_length_b   6.844
_cell_length_c   6.842
_cell_angle_alpha   79.912
_cell_angle_beta   79.912
_cell_angle_gamma   85.332
_symmetry_Int_Tables_number   1
_cell_volume   310.206
_cell_formula_units_Z   4
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  0.818  0.182  0.500  1.0
  Mg  Mg1  1  0.182  0.818  0.500  1.0
  Mg  Mg2  1  0.203  0.203  0.134  1.0
  Mg  Mg3  1  0.797  0.797  0.866  1.0
  Cr  Cr4  1  0.744  0.256  0.000  1.0
  Cr  Cr5  1  0.256  0.744  0.000  1.0
  Cr  Cr6  1  0.726  0.726  0.412  1.0
  Cr  Cr7  1  0.274  0.274  0.588  1.0
  O  O8  1  0.142  0.142  0.460  1.0
  O  O9  1  0.858  0.858  0.540  1.0
  O  O10  1  0.788  0.788  0.168  1.0
  O  O11  1  0.212  0.212  0.832  1.0
  O  O12  1  0.512  0.221  0.103  1.0
  O  O13  1  0.779  0.488  0.897  1.0
  O  O14  1  0.488  0.779  0.897  1.0
  O  O15  1  0.221  0.512  0.103  1.0
  O  O16  1  0.201  0.888  0.184  1.0
  O  O17  1  0.112  0.799  0.816  1.0
  O  O18  1  0.799  0.112  0.816  1.0
  O  O19  1  0.888  0.201  0.184  1.0
  O  O20  1  0.489  0.784  0.477  1.0
  O  O21  1  0.216  0.511  0.523  1.0
  O  O22  1  0.511  0.216  0.523  1.0
  O  O23  1  0.784  0.489  0.477  1.0
[/CIF]
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