data_global _chemical_name_mineral 'Fluoro-eckermannite' loop_ _publ_author_name 'Oberti R' 'Hawthorne F C' 'Camara F' 'Raudsepp M' _journal_name_full 'American Mineralogist' _journal_volume 84 _journal_year 1999 _journal_page_first 102 _journal_page_last 111 _publ_section_title ; Unusual M3+ cations in synthetic amphiboles with nominal fluoro-eckermannite composition: Deviations from stoichiometry and structural effects of the cummingtonite component Sample: V, Na.90Na.92Mg1.08Mg4.98V.02Si8O22F2 ; _database_code_amcsd 0002058 _chemical_formula_sum 'Si8 Mg6.12 V.02 Na1.81 O22 F2' _cell_length_a 9.655 _cell_length_b 17.909 _cell_length_c 5.267 _cell_angle_alpha 90 _cell_angle_beta 102.73 _cell_angle_gamma 90 _cell_volume 888.338 _exptl_crystal_density_diffrn 3.013 _symmetry_space_group_name_H-M 'C 1 2/m 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,z' '1/2+x,1/2-y,z' '-x,y,-z' '1/2-x,1/2+y,-z' '-x,-y,-z' '1/2-x,1/2-y,-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 Si(1) 0.28440 0.08480 0.28160 1.00000 0.00621 Si(2) 0.29240 0.17060 0.78610 1.00000 0.00697 Mg(1) 0.00000 0.08870 0.50000 1.00000 0.00811 V(2) 0.00000 0.17920 0.00000 0.01000 0.01001 Mg(2) 0.00000 0.17920 0.00000 0.99000 0.01001 Mg(3) 0.00000 0.00000 0.00000 1.00000 0.00773 Mg(4) 0.00000 0.26310 0.50000 0.57000 0.02115 Na(4) 0.00000 0.26310 0.50000 0.43000 0.02115 NaA 0.00000 0.50000 0.00000 0.25000 0.03584 NaA(m) 0.04410 0.50000 0.10260 0.35000 0.03217 O1 0.11390 0.08470 0.21340 1.00000 0.00671 O2 0.12070 0.16960 0.72090 1.00000 0.00912 F3 0.10410 0.00000 0.70680 1.00000 0.00925 O4 0.36890 0.24830 0.78300 1.00000 0.01836 O5 0.35020 0.12790 0.06710 1.00000 0.02128 O6 0.34740 0.11890 0.56780 1.00000 0.02850 O7 0.34560 0.00000 0.28290 1.00000 0.01267