data_global _chemical_name_mineral 'Richterite' loop_ _publ_author_name 'Della Ventura G' 'Robert J-L' 'Raudsepp M' 'Hawthorne F C' 'Welch M D' _journal_name_full 'American Mineralogist' _journal_volume 82 _journal_year 1997 _journal_page_first 291 _journal_page_last 301 _publ_section_title ; Site occupancies in synthetic monoclinic amphiboles: Rietveld structure refinement and infrared spectroscopy of (nickel, magnesium, cobalt)-richterite Sample: Co20 ; _database_code_amcsd 0001881 _chemical_formula_sum 'Si8 (Mg3.91 Co1.09) Ca1.1 Na2.72 O24' _cell_length_a 9.9180 _cell_length_b 17.999 _cell_length_c 5.2714 _cell_angle_alpha 90 _cell_angle_beta 104.246 _cell_angle_gamma 90 _cell_volume 912.081 _exptl_crystal_density_diffrn 3.184 _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 Si1 0.28220 0.08540 0.29530 1.00000 Si2 0.28210 0.16990 0.79830 1.00000 Mg1 0.00000 0.08930 0.50000 0.77000 Co1 0.00000 0.08930 0.50000 0.23000 Mg2 0.00000 0.17890 0.00000 0.80000 Co2 0.00000 0.17890 0.00000 0.20000 Mg3 0.00000 0.00000 0.00000 0.77000 Co3 0.00000 0.00000 0.00000 0.23000 Ca4 0.00000 0.27420 0.50000 0.55000 Na4 0.00000 0.27420 0.50000 0.45000 NaA 0.00000 0.47940 0.00000 0.91000 O1 0.11630 0.08790 0.21630 1.00000 O2 0.10570 0.17030 0.72260 1.00000 O3 0.10650 0.00000 0.71020 1.00000 O4 0.35540 0.24740 0.77750 1.00000 O5 0.34180 0.13090 0.08280 1.00000 O6 0.34020 0.11320 0.59150 1.00000 O7 0.33970 0.00000 0.30370 1.00000