The material described by MgCrO2 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted MgO5 trigonal bipyramids that share corners with four equivalent Mg(2)O4 tetrahedra, corners with two equivalent Cr(2)O5 trigonal bipyramids, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Cr(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(2)O4 tetrahedra, corners with four equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Cr(2)O5 trigonal bipyramids, and  an edgeedge with one Cr(2)O5 trigonal bipyramid. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(3) atoms. In the second Cr site, Cr(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CrO5 trigonal bipyramids that share corners with four equivalent Mg(2)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O4 tetrahedra, edges with two equivalent Cr(2)O5 trigonal bipyramids, and  a faceface with one Mg(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms to form distorted OMgCr3 tetrahedra that share corners with two equivalent O(1)MgCr3 tetrahedra, corners with four equivalent O(3)Mg3Cr2 trigonal bipyramids,  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(4)Mg3Cr2 trigonal bipyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(2) and two equivalent Cr(2) atoms. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Cr(1) atoms to form distorted OMg3Cr2 trigonal bipyramids that share corners with four equivalent O(1)MgCr3 tetrahedra, corners with three equivalent O(4)Mg3Cr2 trigonal bipyramids,  an edgeedge with one O(1)MgCr3 tetrahedra,  an edgeedge with one O(4)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(3)Mg3Cr2 trigonal bipyramids. In the fourth O site, O(4) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Cr(2) atoms to form distorted OMg3Cr2 trigonal bipyramids that share corners with three equivalent O(3)Mg3Cr2 trigonal bipyramids, edges with two equivalent O(1)MgCr3 tetrahedra,  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(4)Mg3Cr2 trigonal bipyramids. is represented by the CIF card [CIF]
data_MgCrO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.963
_cell_length_b   8.480
_cell_length_c   8.561
_cell_angle_alpha   85.882
_cell_angle_beta   80.187
_cell_angle_gamma   79.974
_symmetry_Int_Tables_number   1
_cell_volume   208.554
_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  0.654  0.925  0.274  1.0
  Mg  Mg1  1  0.346  0.075  0.726  1.0
  Mg  Mg2  1  0.922  0.280  0.378  1.0
  Mg  Mg3  1  0.078  0.720  0.622  1.0
  Cr  Cr4  1  0.373  0.810  0.942  1.0
  Cr  Cr5  1  0.790  0.606  0.317  1.0
  Cr  Cr6  1  0.210  0.394  0.683  1.0
  Cr  Cr7  1  0.627  0.190  0.058  1.0
  O  O8  1  0.186  0.223  0.905  1.0
  O  O9  1  0.625  0.570  0.678  1.0
  O  O10  1  0.375  0.430  0.322  1.0
  O  O11  1  0.814  0.777  0.095  1.0
  O  O12  1  0.913  0.898  0.769  1.0
  O  O13  1  0.167  0.782  0.393  1.0
  O  O14  1  0.087  0.102  0.231  1.0
  O  O15  1  0.833  0.218  0.607  1.0
[/CIF]
.
The material described by MgCrO2 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(1), two equivalent O(3), and two equivalent O(4) atoms to form distorted MgO5 trigonal bipyramids that share corners with four equivalent Mg(2)O4 tetrahedra, corners with two equivalent Cr(2)O5 trigonal bipyramids, edges with two equivalent Mg(1)O5 trigonal bipyramids, and  a faceface with one Cr(2)O5 trigonal bipyramid. In the second Mg site, Mg(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form MgO4 tetrahedra that share corners with two equivalent Mg(2)O4 tetrahedra, corners with four equivalent Mg(1)O5 trigonal bipyramids, corners with four equivalent Cr(2)O5 trigonal bipyramids, and  an edgeedge with one Cr(2)O5 trigonal bipyramid. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(1) and two equivalent O(3) atoms. In the second Cr site, Cr(2) is bonded to one O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted CrO5 trigonal bipyramids that share corners with four equivalent Mg(2)O4 tetrahedra, corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O4 tetrahedra, edges with two equivalent Cr(2)O5 trigonal bipyramids, and  a faceface with one Mg(1)O5 trigonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), one Cr(2), and two equivalent Cr(1) atoms to form distorted OMgCr3 tetrahedra that share corners with two equivalent O(1)MgCr3 tetrahedra, corners with four equivalent O(3)Mg3Cr2 trigonal bipyramids,  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(4)Mg3Cr2 trigonal bipyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(2) and two equivalent Cr(2) atoms. In the third O site, O(3) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Cr(1) atoms to form distorted OMg3Cr2 trigonal bipyramids that share corners with four equivalent O(1)MgCr3 tetrahedra, corners with three equivalent O(4)Mg3Cr2 trigonal bipyramids,  an edgeedge with one O(1)MgCr3 tetrahedra,  an edgeedge with one O(4)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(3)Mg3Cr2 trigonal bipyramids. In the fourth O site, O(4) is bonded to one Mg(2), two equivalent Mg(1), and two equivalent Cr(2) atoms to form distorted OMg3Cr2 trigonal bipyramids that share corners with three equivalent O(3)Mg3Cr2 trigonal bipyramids, edges with two equivalent O(1)MgCr3 tetrahedra,  an edgeedge with one O(3)Mg3Cr2 trigonal bipyramid, and edges with two equivalent O(4)Mg3Cr2 trigonal bipyramids. is represented by the CIF card [CIF]
data_MgCrO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.963
_cell_length_b   8.480
_cell_length_c   8.561
_cell_angle_alpha   85.882
_cell_angle_beta   80.187
_cell_angle_gamma   79.974
_symmetry_Int_Tables_number   1
_cell_volume   208.554
_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  0.654  0.925  0.274  1.0
  Mg  Mg1  1  0.346  0.075  0.726  1.0
  Mg  Mg2  1  0.922  0.280  0.378  1.0
  Mg  Mg3  1  0.078  0.720  0.622  1.0
  Cr  Cr4  1  0.373  0.810  0.942  1.0
  Cr  Cr5  1  0.790  0.606  0.317  1.0
  Cr  Cr6  1  0.210  0.394  0.683  1.0
  Cr  Cr7  1  0.627  0.190  0.058  1.0
  O  O8  1  0.186  0.223  0.905  1.0
  O  O9  1  0.625  0.570  0.678  1.0
  O  O10  1  0.375  0.430  0.322  1.0
  O  O11  1  0.814  0.777  0.095  1.0
  O  O12  1  0.913  0.898  0.769  1.0
  O  O13  1  0.167  0.782  0.393  1.0
  O  O14  1  0.087  0.102  0.231  1.0
  O  O15  1  0.833  0.218  0.607  1.0
[/CIF]
.