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: Mg(100) ; _database_code_amcsd 0001875 _chemical_formula_sum 'Si8 Mg5 Ca1.05 Na2.85 O24' _cell_length_a 9.9076 _cell_length_b 17.988 _cell_length_c 5.2706 _cell_angle_alpha 90 _cell_angle_beta 104.252 _cell_angle_gamma 90 _cell_volume 910.405 _exptl_crystal_density_diffrn 3.056 _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 0.28080 0.08530 0.29770 1.00000 Si2 0.28470 0.16970 0.79730 1.00000 Mg1 0.00000 0.08920 0.50000 1.00000 Mg2 0.00000 0.17720 0.00000 1.00000 Mg3 0.00000 0.00000 0.00000 1.00000 Ca4 0.00000 0.27510 0.50000 0.52500 Na4 0.00000 0.27510 0.50000 0.47500 NaA 0.00000 0.47910 0.00000 0.95000 O1 0.11650 0.08700 0.22340 1.00000 O2 0.10790 0.16950 0.71690 1.00000 O3 0.10660 0.00000 0.71200 1.00000 O4 0.35380 0.24930 0.77960 1.00000 O5 0.34330 0.12960 0.08630 1.00000 O6 0.33890 0.11220 0.59660 1.00000 O7 0.33790 0.00000 0.30250 1.00000