data_global _chemical_name_mineral 'Combeite' loop_ _publ_author_name 'Fischer R X' 'Tillmanns E' _journal_name_full 'Neues Jahrbuch fur Mineralogie, Monatshefte' _journal_volume 1983 _journal_year 1983 _journal_page_first 49 _journal_page_last 59 _publ_section_title ; Die Kristallstrukturen von naturlichem Na2Ca2Si3O9 vom Mt.Shaheru (Zaire) und aus dem Mayener Feld (Eifel) Note: this is the low-temperature form of combeite ; _database_code_amcsd 0019534 _chemical_compound_source 'Mayener Feld, Eifel, Germany' _chemical_formula_sum 'Na4.5 Ca3.5 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 2.792 _symmetry_space_group_name_H-M 'P 32' loop_ _space_group_symop_operation_xyz 'x,y,z' '-y,x-y,2/3+z' '-x+y,-x,1/3+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 Nal 0.65030 0.00670 0.41440 0.50000 0.01646 Na2 0.99350 0.16180 0.34420 1.00000 0.01773 Na3 0.50420 0.67840 0.33890 1.00000 0.01418 Na4 0.65200 0.50900 0.67900 1.00000 0.01773 Na5 0.14680 0.97230 0.18070 1.00000 0.01494 Cal 0.97510 0.64210 0.33950 1.00000 0.00836 Ca2 0.84380 0.33320 0.50550 1.00000 0.00836 Ca3 0.30330 0.81230 0.49650 1.00000 0.01798 Ca4 0.98280 0.66170 0.59150 0.50000 0.01406 Si1 0.47100 0.18110 0.56230 1.00000 0.01026 Si2 0.19040 0.48190 0.43580 1.00000 0.00367 Si3 0.62070 0.48400 0.44720 1.00000 0.00671 Si4 0.48960 0.65530 0.56750 1.00000 0.00583 Si5 0.81760 0.85640 0.24050 1.00000 0.00836 Si6 0.84550 0.83100 0.77620 1.00000 0.00773 O1 0.60150 0.61310 0.50770 1.00000 0.01520 O2 0.66600 0.17090 0.17180 1.00000 0.02533 O3 0.34700 0.59900 0.49290 1.00000 0.01520 O4 0.77800 0.89070 0.34980 1.00000 0.01773 O5 0.89400 0.80400 0.67260 1.00000 0.01773 O6 0.47730 0.26590 0.13050 1.00000 0.01140 O7 0.26100 0.43310 0.89400 1.00000 0.01646 O8 0.16200 0.23500 0.11620 1.00000 0.01900 O9 0.88660 0.75200 0.22770 1.00000 0.01393 O10 0.51680 0.08800 0.00090 1.00000 0.01646 O11 0.44100 0.57650 0.67600 1.00000 0.01393 O12 0.76130 0.57660 0.01280 1.00000 0.01646 O13 0.55400 0.78000 0.99490 1.00000 0.01773 O14 0.93100 0.01100 0.18320 1.00000 0.01773 O15 0.73300 0.67660 0.83680 1.00000 0.01773 O16 0.66600 0.77500 0.17270 1.00000 0.02406 O17 0.85460 0.45330 0.21250 1.00000 0.00887 O18 0.44800 0.53100 0.11480 1.00000 0.01900