The structure described by Ca2Mg crystallizes in the trigonal P-3m1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent Ca(2) and nine equivalent Ca(1) atoms to form CaCa12 cuboctahedra that share corners with six equivalent Ca(1)Ca12 cuboctahedra, corners with twelve equivalent Ca(2)Ca3Mg3 cuboctahedra, edges with six equivalent Ca(2)Ca3Mg3 cuboctahedra, edges with twelve equivalent Ca(1)Ca12 cuboctahedra,  a faceface with one Ca(2)Ca3Mg3 cuboctahedra, and faces with twelve equivalent Ca(1)Ca12 cuboctahedra. In the second Ca site, Ca(2) is bonded to three equivalent Ca(1) and three equivalent Mg(1) atoms to form distorted CaCa3Mg3 cuboctahedra that share corners with twelve equivalent Ca(1)Ca12 cuboctahedra, edges with six equivalent Ca(1)Ca12 cuboctahedra, edges with six equivalent Ca(2)Ca3Mg3 cuboctahedra, and  a faceface with one Ca(1)Ca12 cuboctahedra. Mg(1) is bonded in a 6-coordinate geometry to three equivalent Ca(2) and three equivalent Mg(1) atoms. is represented by the CIF file [CIF]
data_Ca2Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.736
_cell_length_b   3.736
_cell_length_c   17.992
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   217.522
_cell_formula_units_Z   2
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  0.333  0.667  0.908  1.0
  Ca  Ca1  1  0.667  0.333  0.725  1.0
  Ca  Ca2  1  0.333  0.667  0.275  1.0
  Ca  Ca3  1  0.667  0.333  0.092  1.0
  Mg  Mg4  1  0.333  0.667  0.570  1.0
  Mg  Mg5  1  0.667  0.333  0.430  1.0
[/CIF]
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The structure described by Ca2Mg crystallizes in the trigonal P-3m1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent Ca(2) and nine equivalent Ca(1) atoms to form CaCa12 cuboctahedra that share corners with six equivalent Ca(1)Ca12 cuboctahedra, corners with twelve equivalent Ca(2)Ca3Mg3 cuboctahedra, edges with six equivalent Ca(2)Ca3Mg3 cuboctahedra, edges with twelve equivalent Ca(1)Ca12 cuboctahedra,  a faceface with one Ca(2)Ca3Mg3 cuboctahedra, and faces with twelve equivalent Ca(1)Ca12 cuboctahedra. In the second Ca site, Ca(2) is bonded to three equivalent Ca(1) and three equivalent Mg(1) atoms to form distorted CaCa3Mg3 cuboctahedra that share corners with twelve equivalent Ca(1)Ca12 cuboctahedra, edges with six equivalent Ca(1)Ca12 cuboctahedra, edges with six equivalent Ca(2)Ca3Mg3 cuboctahedra, and  a faceface with one Ca(1)Ca12 cuboctahedra. Mg(1) is bonded in a 6-coordinate geometry to three equivalent Ca(2) and three equivalent Mg(1) atoms. is represented by the CIF file [CIF]
data_Ca2Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.736
_cell_length_b   3.736
_cell_length_c   17.992
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   217.522
_cell_formula_units_Z   2
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  0.333  0.667  0.908  1.0
  Ca  Ca1  1  0.667  0.333  0.725  1.0
  Ca  Ca2  1  0.333  0.667  0.275  1.0
  Ca  Ca3  1  0.667  0.333  0.092  1.0
  Mg  Mg4  1  0.333  0.667  0.570  1.0
  Mg  Mg5  1  0.667  0.333  0.430  1.0
[/CIF]
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