The crystal structure described by Mg3Ca crystallizes in the orthorhombic Pmm2 space group. Ca(1) is bonded to two equivalent Ca(1), two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms to form a mixture of distorted edge, corner, and face-sharing CaCa2Mg10 cuboctahedra. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to four equivalent Ca(1), two equivalent Mg(2), and four equivalent Mg(3) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to four equivalent Ca(1), two equivalent Mg(1), and four equivalent Mg(3) atoms. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Ca(1), two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms. is represented by the CIF file [CIF]
data_CaMg3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.529
_cell_length_b   5.374
_cell_length_c   5.797
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   109.964
_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  0.000  0.000  0.173  1.0
  Mg  Mg1  1  0.500  0.000  0.663  1.0
  Mg  Mg2  1  0.500  0.500  0.344  1.0
  Mg  Mg3  1  0.000  0.500  0.819  1.0
[/CIF]
.
The crystal structure described by Mg3Ca crystallizes in the orthorhombic Pmm2 space group. Ca(1) is bonded to two equivalent Ca(1), two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms to form a mixture of distorted edge, corner, and face-sharing CaCa2Mg10 cuboctahedra. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to four equivalent Ca(1), two equivalent Mg(2), and four equivalent Mg(3) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to four equivalent Ca(1), two equivalent Mg(1), and four equivalent Mg(3) atoms. In the third Mg site, Mg(3) is bonded in a 12-coordinate geometry to two equivalent Ca(1), two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms. is represented by the CIF file [CIF]
data_CaMg3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.529
_cell_length_b   5.374
_cell_length_c   5.797
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   109.964
_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  0.000  0.000  0.173  1.0
  Mg  Mg1  1  0.500  0.000  0.663  1.0
  Mg  Mg2  1  0.500  0.500  0.344  1.0
  Mg  Mg3  1  0.000  0.500  0.819  1.0
[/CIF]
.