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 DAC
;
_database_code_amcsd 0004423
_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 9.9910
_cell_length_b 9.9910
_cell_length_c 8.3702
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 723.576
_exptl_crystal_density_diffrn      2.630
_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   0.00510   0.54000   0.03200
NaK   0.00000   0.00000   0.00510   0.24000   0.03200
CaK   0.00000   0.00000   0.00510   0.03000   0.03200
Na   0.55384   0.99711   0.50710   1.00000   0.02390
AlT1   0.66667   0.33333   0.70280   1.00000   0.00690
SiT2   0.66667   0.33333   0.31440   1.00000   0.01730
SiT3   0.90486   0.66596   0.82172   1.00000   0.01120
AlT4   0.90743   0.66818   0.19535   1.00000   0.01280
O1   0.65650   0.28570   0.50220   0.33333   0.02340
O2   0.97400   0.68440   0.00210   1.00000   0.02440
O3   0.82200   0.47430   0.23040   1.00000   0.03730
O4   0.83930   0.49050   0.75260   1.00000   0.01980
O5   0.77050   0.71300   0.82260   1.00000   0.01080
O6   0.77870   0.73690   0.20160   1.00000   0.02740