data_CaMg7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.61
_cell_length_b   6.61
_cell_length_c   6.61
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CaMg7
_chemical_formula_sum   'Ca1 Mg7'
_cell_volume   203.97
_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  0.67  0.67  0.67  1.0
  Mg  Mg1  1  0.34  0.34  0.67  1.0
  Mg  Mg2  1  0.34  0.67  0.34  1.0
  Mg  Mg3  1  0.0  0.34  0.34  1.0
  Mg  Mg4  1  0.67  0.34  0.34  1.0
  Mg  Mg5  1  0.34  0.0  0.34  1.0
  Mg  Mg6  1  0.34  0.34  0.0  1.0
  Mg  Mg7  1  0.0  0.0  0.0  1.0

data_CaMg7
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.61
_cell_length_b   6.61
_cell_length_c   16.18
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   CaMg7
_chemical_formula_sum   'Ca3 Mg21'
_cell_volume   611.91
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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  3  0.0  0.0  0.33  1.0
  Mg  Mg1  9  0.11  0.55  0.22  1.0
  Mg  Mg2  9  0.22  0.44  0.44  1.0
  Mg  Mg3  3  0.0  0.0  0.0  1.0

Ca Mg Mg Mg Mg Mg Mg Mg
Ca Mg Mg Mg Mg Mg Mg Mg 0 6 o o + 0 4 o o o 0 4 o o + 0 4 o + o 0 1 o o o 0 1 o + o 0 1 + o o 0 5 o + o 0 2 o o o 0 2 o o + 0 2 + o o 0 7 o + + 0 7 + o + 0 7 + + o 0 3 + o o 1 4 o o o 1 6 o o + 1 2 o o o 1 7 o o + 2 4 o o o 2 5 o + o 2 7 o + o 3 4 - o o 3 6 o o o 3 5 o o o 3 7 o + o 3 7 o o + 3 7 o o o 4 7 + o o 5 6 o o o 5 7 + o o 5 7 o o + 5 7 o o o 6 7 + o o 6 7 o + o 6 7 o o o 
CaMg7 crystallizes in the trigonal R3m space group. Ca(1) is bonded in a 3-coordinate geometry to three equivalent Mg(2) and three equivalent Mg(3) atoms. All Ca(1)-Mg(2) bond lengths are 3.14 Å. All Ca(1)-Mg(3) bond lengths are 3.82 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(3) is bonded in a distorted hexagonal planar geometry to three equivalent Ca(1) and three equivalent Mg(1) atoms. All Mg(3)-Mg(1) bond lengths are 3.14 Å. In the second Mg site, Mg(1) is bonded in a 3-coordinate geometry to one Mg(2), one Mg(3), and two equivalent Mg(1) atoms. The Mg(1)-Mg(2) bond length is 2.17 Å. Both Mg(1)-Mg(1) bond lengths are 2.22 Å. In the third Mg site, Mg(2) is bonded in a rectangular see-saw-like geometry to one Ca(1), one Mg(1), and two equivalent Mg(2) atoms. Both Mg(2)-Mg(2) bond lengths are 2.22 Å.