data_global
_chemical_name_mineral 'Combeite'
loop_
_publ_author_name
'Fischer R X'
'Tillmanns E'
_journal_name_full 'Acta Crystallographica, Section C'
_journal_volume 43 
_journal_year 1987
_journal_page_first 1852
_journal_page_last 1854
_publ_section_title
;
 Revised data for combeite, Na2Ca2Si3O9
;
_database_code_amcsd 0010050
_chemical_compound_source 'synthetic low-temperature form'
_chemical_formula_sum 'Na4.4 Ca3.8 Si6 O18'
_cell_length_a 10.464
_cell_length_b 10.464
_cell_length_c 13.176
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 1249.423
_exptl_crystal_density_diffrn      2.831
_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   0.31250   0.98450   0.58890   0.52000   0.01600
Ca1   0.31250   0.98450   0.58890   0.43000   0.01600
Na21   0.50320   0.33660   0.66440   1.00000   0.02300
Na22   0.81150   0.00000   0.33333   0.40000   0.04900
Na31   0.51960   0.36180   0.15790   0.48000   0.02300
Ca31   0.51960   0.36180   0.15790   0.47000   0.02300
Ca32   0.82170   0.00000   0.83333   1.00000   0.01000
Ca4   0.30830   0.00000   0.33333   1.00000   0.00700
Sil   0.19780   0.15230   0.77590   1.00000   0.00700
Si2   0.49730   0.32070   0.89580   1.00000   0.00700
Si3   0.62690   0.14890   0.76430   1.00000   0.00700
Ol   0.16160   0.00000   0.83333   1.00000   0.02800
O2   0.55910   0.00000   0.83333   1.00000   0.02800
O3   0.34450   0.27870   0.83540   1.00000   0.01700
O4   0.58610   0.26390   0.82170   1.00000   0.02100
O5   0.24390   0.14790   0.66110   1.00000   0.01600
O6   0.46830   0.24350   0.00150   1.00000   0.02300
O7   0.55470   0.11090   0.65520   1.00000   0.01900
O8   0.06880   0.18920   0.79220   1.00000   0.01300
O9   0.59390   0.49610   0.88810   1.00000   0.01800
O10   0.80110   0.21840   0.77740   1.00000   0.01600