data_global _chemical_name_mineral 'Nepheline' loop_ _publ_author_name 'Simmons W B' 'Peacor D R' _journal_name_full 'American Mineralogist' _journal_volume 57 _journal_year 1972 _journal_page_first 1711 _journal_page_last 1719 _publ_section_title ; Refinement of the crystal structure of a volcanic nepheline ; _database_code_amcsd 296 _chemical_formula_sum 'Na3 K (Al3.6 Si4.4) O15.999' _cell_length_a 10.003 _cell_length_b 10.003 _cell_length_c 8.381 _cell_angle_alpha 90.0 _cell_angle_beta 90.0 _cell_angle_gamma 120.0 _cell_volume 726.251 _exptl_crystal_density_diffrn 2.674 _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 _atom_site_occupancy Na 0.9972 0.4432 0.9913 1.0 K 0.0 0.0 0.9893 1.0 Al1 0.333333 0.666667 0.1877 0.51 Si1 0.333333 0.666667 0.1877 0.49 Si2 0.333333 0.666667 0.799 0.58 Al2 0.333333 0.666667 0.799 0.42 Si3 0.0933 0.3344 0.309 0.84 Al3 0.0933 0.3344 0.309 0.16 Al4 0.0934 0.3318 0.6824 0.73 Si4 0.0934 0.3318 0.6824 0.27 O1 0.3327 0.7024 0.9846 0.333 O2 0.0269 0.3168 0.4921 1.0 O3 0.1713 0.5235 0.721 1.0 O4 0.1647 0.5108 0.2393 1.0 O5 0.2258 0.2873 0.3099 1.0 O6 0.2229 0.2657 0.6892 1.0 loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 Na 0.03117 0.01901 0.01922 0.01217 0.00147 0.0011 K 0.03878 0.03878 0.03452 0.01939 0.0 0.0 Al1 0.01369 0.01369 0.01245 0.00684 0.0 0.0 Si1 0.01369 0.01369 0.01245 0.00684 0.0 0.0 Si2 0.02281 0.02281 0.01423 0.01141 0.0 0.0 Al2 0.02281 0.02281 0.01423 0.01141 0.0 0.0 Si3 0.00798 0.00874 0.01566 0.00342 -0.00331 -0.0011 Al3 0.00798 0.00874 0.01566 0.00342 -0.00331 -0.0011 Al4 0.01026 0.01255 0.00961 0.00608 -0.00441 -0.00184 Si4 0.01026 0.01255 0.00961 0.00608 -0.00441 -0.00184 O1 0.04296 0.03003 0.03736 0.03079 -0.03053 -0.02501 O2 0.02357 0.04562 0.01566 0.02319 -0.00772 -0.00662 O3 0.02509 0.02167 0.06512 0.01331 0.00037 0.00809 O4 0.00836 0.00836 0.03665 0.0019 -0.00147 0.00589 O5 0.01407 0.02623 0.01032 0.01445 -0.00184 0.0 O6 0.02395 0.01673 0.02918 0.01445 -0.00405 0.0011