data_global
_chemical_name_mineral 'Combeite'
loop_
_publ_author_name
'Ohsato H'
'Takeuchi Y'
'Maki I'
_journal_name_full 'Acta Crystallographica, Section C'
_journal_volume 42 
_journal_year 1986
_journal_page_first 934
_journal_page_last 937
_publ_section_title
;
 Structure of Na4Ca4[Si6O18]
;
_database_code_amcsd 0010031
_chemical_compound_source 'synthetic low-temperature form'
_chemical_formula_sum '(Na2 Ca2) Si3 O9'
_cell_length_a 10.464
_cell_length_b 10.464
_cell_length_c 13.168
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 1248.665
_exptl_crystal_density_diffrn      2.828
_symmetry_space_group_name_H-M 'P 31 2 1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  'y,x,-z'
  '-y,x-y,1/3+z'
  '-x,-x+y,1/3-z'
  '-x+y,-x,2/3+z'
  'x-y,-y,2/3-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
_atom_site_U_iso_or_equiv
Na1   0.30860   0.98300   0.58920   0.42000   0.00747
Ca1   0.30860   0.98300   0.58920   0.29000   0.00747
Nal*   0.28210   0.97040   0.61510   0.17000   0.03293
Cal*   0.28210   0.97040   0.61510   0.12000   0.03293
Na2   0.50410   0.33800   0.66420   1.00000   0.02140
Ca31   0.52620   0.37040   0.15580   0.59000   0.01976
Na31   0.52620   0.37040   0.15580   0.41000   0.01976
Ca32   0.82030   0.00000   0.83333   1.00000   0.00963
Ca4   0.30390   0.00000   0.33333   1.00000   0.00747
Sil   0.19860   0.15260   0.77800   1.00000   0.00583
Si2   0.49960   0.32340   0.89580   1.00000   0.00684
Si3   0.62430   0.14850   0.76350   1.00000   0.00633
O11   0.16710   0.00000   0.83333   1.00000   0.01773
O12   0.55550   0.00000   0.83333   1.00000   0.02026
O13   0.34420   0.28420   0.83820   1.00000   0.01140
O14   0.58490   0.26430   0.81990   1.00000   0.01330
O21   0.24680   0.15350   0.66220   1.00000   0.01381
O22   0.47820   0.24720   0.00320   1.00000   0.01545
O23   0.55130   0.11040   0.65400   1.00000   0.01748
O31   0.06520   0.18530   0.79490   1.00000   0.01001
O32   0.59650   0.49910   0.88800   1.00000   0.01748
O33   0.79900   0.21840   0.77630   1.00000   0.01355