data_global _chemical_name_mineral 'Norbergite' loop_ _publ_author_name 'Gibbs G V' 'Ribbe P H' _journal_name_full 'American Mineralogist' _journal_volume 54 _journal_year 1969 _journal_page_first 376 _journal_page_last 390 _publ_section_title ; The crystal structures of the humite minerals: I. Norbergite ; _database_code_amcsd 0000190 _chemical_formula_sum 'Mg3 Si O4.2 (F1.8 H.2)' _cell_length_a 4.7104 _cell_length_b 10.2718 _cell_length_c 8.7476 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 423.246 _exptl_crystal_density_diffrn 3.179 _symmetry_space_group_name_H-M 'P b n m' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,y,1/2-z' '-x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' '1/2-x,1/2+y,1/2-z' '1/2-x,1/2+y,z' '1/2+x,1/2-y,-z' '-x,-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 Mg1 0.98900 0.63300 0.43050 1.00000 0.00418 Mg2 0.99240 0.90770 0.25000 1.00000 0.00481 Si 0.41950 0.71960 0.25000 1.00000 0.00355 O1 0.76170 0.72040 0.25000 1.00000 0.00481 O2 0.27930 0.57400 0.25000 1.00000 0.00405 O3 0.26900 0.79070 0.10340 1.00000 0.00405 F 0.72950 0.96820 0.08340 0.90000 0.00937 O-H 0.72950 0.96820 0.08340 0.10000 0.00937