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: Ni40 ; _database_code_amcsd 0001877 _chemical_formula_sum 'Si8 (Mg2.96 Ni2.04) Ca1.12 Na2.64 O24' _cell_length_a 9.9024 _cell_length_b 17.965 _cell_length_c 5.2603 _cell_angle_alpha 90 _cell_angle_beta 104.361 _cell_angle_gamma 90 _cell_volume 906.548 _exptl_crystal_density_diffrn 3.319 _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 0.28630 0.08570 0.30020 1.00000 Si2 0.28150 0.16810 0.79540 1.00000 Mg1 0.00000 0.08870 0.50000 0.51000 Ni1 0.00000 0.08870 0.50000 0.49000 Mg2 0.00000 0.17690 0.00000 0.73000 Ni2 0.00000 0.17690 0.00000 0.27000 Mg3 0.00000 0.00000 0.00000 0.48000 Ni3 0.00000 0.00000 0.00000 0.52000 Ca4 0.00000 0.27490 0.50000 0.56000 Na4 0.00000 0.27490 0.50000 0.44000 NaA 0.00000 0.48350 0.00000 0.88000 O1 0.11860 0.08860 0.22170 1.00000 O2 0.09920 0.16980 0.71450 1.00000 O3 0.10550 0.00000 0.71190 1.00000 O4 0.35330 0.24860 0.77470 1.00000 O5 0.34110 0.12910 0.08050 1.00000 O6 0.34070 0.11110 0.59870 1.00000 O7 0.33790 0.00000 0.29120 1.00000