data_global
_chemical_name_mineral 'Nepheline'
loop_
_publ_author_name
'Gatta G D'
'Angel R J'
_journal_name_full 'American Mineralogist'
_journal_volume 92 
_journal_year 2007
_journal_page_first 1446
_journal_page_last 1455
_publ_section_title
;
 Elastic behavior and pressure-induced structural evolution of nepheline:
 Implications for the nature of the modulated superstructure
 Sample: P = .0001 GPa, in air
;
_database_code_amcsd 0004422
_chemical_compound_source 'intrusive aplite of Snipe River, Tambani, Nyasaland, Malawi'
_chemical_formula_sum 'K.54 Na3.24 Ca.03 Al4 Si4 O16'
_cell_length_a 9.9995
_cell_length_b 9.9995
_cell_length_c 8.3766
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 725.362
_exptl_crystal_density_diffrn      2.624
_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
_atom_site_U_iso_or_equiv
K   0.00000   0.00000   0.00410   0.54000   0.03296
NaK   0.00000   0.00000   0.00410   0.24000   0.03296
CaK   0.00000   0.00000   0.00410   0.03000   0.03296
Na   0.55412   0.99724   0.50845   1.00000   0.02537
AlT1   0.66667   0.33333   0.70194   1.00000   0.01271
SiT2   0.66667   0.33333   0.31362   1.00000   0.01423
SiT3   0.90568   0.66614   0.82276   1.00000   0.01378
AlT4   0.90645   0.66759   0.19630   1.00000   0.01235
O1   0.66190   0.28910   0.50178   0.33333   0.03350
O2   0.97288   0.68347   0.00309   1.00000   0.03350
O3   0.82649   0.47750   0.25170   1.00000   0.03807
O4   0.83665   0.48973   0.76444   1.00000   0.03390
O5   0.77365   0.71475   0.82462   1.00000   0.02064
O6   0.77607   0.73287   0.20149   1.00000   0.02315