data_global _chemical_name_mineral 'Birnessite' loop_ _publ_author_name 'Post J E' 'Veblen D R' _journal_name_full 'American Mineralogist' _journal_volume 75 _journal_year 1990 _journal_page_first 477 _journal_page_last 489 _publ_section_title ; Crystal structure determinations of synthetic sodium, magnesium and potassium birnessite using TEM and the Rietveld method Sample: Mg-birn ; _database_code_amcsd 0001301 _chemical_formula_sum 'Mn O2.85 Mg.144 H1.7' _cell_length_a 5.050 _cell_length_b 2.846 _cell_length_c 7.054 _cell_angle_alpha 90 _cell_angle_beta 96.63 _cell_angle_gamma 90 _cell_volume 100.704 _exptl_crystal_density_diffrn 3.487 _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 Mn 0.00000 0.00000 0.00000 1.00000 0.00633 O1 0.35600 0.00000 0.14100 1.00000 0.01267 Mg 0.02300 0.00000 0.28200 0.07200 0.00633 Wat2 0.70300 0.00000 0.50600 0.42500 0.01900