data_[Ca4Mg2C6O18]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Ca  1.0000  1.8000  1.1400
  Mg  1.3100  1.5000  0.8600
  C  2.5500  0.7000  0.3000
  O  3.4400  0.6000  1.2600
]
_symmetry_space_group_name_H-M [P31c]
_cell_length_a [4.9106]
_cell_length_b [4.9106]
_cell_length_c [16.7463]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [120.0000]
_symmetry_Int_Tables_number [159]
_chemical_formula_structural [Ca2Mg(CO3)3]
_chemical_formula_sum '[Ca4 Mg2 C6 O18]'
_cell_volume [349.7213]
_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  2  0.0000  0.0000  0.4980  1
  Ca  Ca1  2  0.3333  0.6667  0.3168  1
  Mg  Mg2  2  0.3333  0.6667  0.6583  1
  C  C3  2  0.0000  0.0000  0.2317  1
  C  C4  2  0.3333  0.6667  0.0857  1
  C  C5  2  0.3333  0.6667  0.9058  1
  O  O6  6  0.0396  0.2822  0.7328  1
  O  O7  6  0.0513  0.6274  0.0843  1
  O  O8  6  0.0701  0.6689  0.9061  1
]