The structure described by MgCa3 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent Ca(1), six equivalent Ca(2), and four equivalent Mg(1) atoms to form a mixture of distorted corner, face, and edge-sharing CaCa8Mg4 cuboctahedra. In the second Ca site, Ca(2) is bonded in a 2-coordinate geometry to three equivalent Ca(1) and two equivalent Mg(1) atoms. Mg(1) is bonded in a 8-coordinate geometry to four equivalent Ca(1) and four equivalent Ca(2) atoms. is represented by the CIF file [CIF]
data_Ca3Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.186
_cell_length_b   7.186
_cell_length_c   7.186
_cell_angle_alpha   149.788
_cell_angle_beta   126.958
_cell_angle_gamma   62.264
_symmetry_Int_Tables_number   1
_cell_volume   147.869
_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
  Ca  Ca0  1  0.849  0.500  0.349  1.0
  Ca  Ca1  1  0.257  0.265  0.992  1.0
  Ca  Ca2  1  0.726  0.735  0.992  1.0
  Mg  Mg3  1  0.334  0.000  0.334  1.0
[/CIF]
.
The structure described by MgCa3 crystallizes in the orthorhombic Imm2 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent Ca(1), six equivalent Ca(2), and four equivalent Mg(1) atoms to form a mixture of distorted corner, face, and edge-sharing CaCa8Mg4 cuboctahedra. In the second Ca site, Ca(2) is bonded in a 2-coordinate geometry to three equivalent Ca(1) and two equivalent Mg(1) atoms. Mg(1) is bonded in a 8-coordinate geometry to four equivalent Ca(1) and four equivalent Ca(2) atoms. is represented by the CIF file [CIF]
data_Ca3Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.186
_cell_length_b   7.186
_cell_length_c   7.186
_cell_angle_alpha   149.788
_cell_angle_beta   126.958
_cell_angle_gamma   62.264
_symmetry_Int_Tables_number   1
_cell_volume   147.869
_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
  Ca  Ca0  1  0.849  0.500  0.349  1.0
  Ca  Ca1  1  0.257  0.265  0.992  1.0
  Ca  Ca2  1  0.726  0.735  0.992  1.0
  Mg  Mg3  1  0.334  0.000  0.334  1.0
[/CIF]
.