data_global _chemical_name_mineral 'Nepheline' loop_ _publ_author_name 'Buerger M J' 'Klein G E' 'Hamburger G E' _journal_name_full 'American Mineralogist' _journal_volume 32 _journal_year 1947 _journal_page_first 197 _journal_page_last 197 _publ_section_title ; The structure of nepheline ; _database_code_amcsd 40 _chemical_formula_sum 'K Na3 Si4 Al4 O16' _cell_length_a 10.05 _cell_length_b 10.05 _cell_length_c 8.38 _cell_angle_alpha 90.0 _cell_angle_beta 90.0 _cell_angle_gamma 120.0 _cell_volume 733.005 _exptl_crystal_density_diffrn 2.647 _symmetry_space_group_name_H-M 'P 63' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x-y,x,1/2+z' '-y,x-y,z' '-x,-y,1/2+z' '-x+y,-x,z' 'y,-x+y,1/2+z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z K 0.0 0.0 0.0 Na 0.01 0.43 0.0 Si1 0.333333 0.666667 0.82 Al1 0.333333 0.666667 0.18 Si2 0.09 0.33 0.333333 Al2 0.09 0.33 0.666667 O1 0.333333 0.666667 0.0 O2 0.09 0.33 0.5 O3 0.17 0.52 0.75 O4 0.17 0.52 0.25 O5 0.25 0.28 0.25 O6 0.25 0.28 0.75