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 = 7.462 GPa
;
_database_code_amcsd 0004427
_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 9.5587
_cell_length_b 9.5587
_cell_length_c 8.1051
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 641.337
_exptl_crystal_density_diffrn      2.968
_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   0.00280   0.54000   0.02200
NaK   0.00000   0.00000   0.00280   0.24000   0.02200
CaK   0.00000   0.00000   0.00280   0.03000   0.02200
Na   0.56008   0.00140   0.50640   1.00000   0.01950
AlT1   0.66667   0.33333   0.71012   1.00000   0.01080
SiT2   0.66667   0.33333   0.30483   1.00000   0.01010
SiT3   0.92358   0.67276   0.82528   1.00000   0.01000
AlT4   0.92423   0.67448   0.19201   1.00000   0.01140
O1   0.66667   0.33333   0.50180   1.00000   0.02990
O2   0.01431   0.70341   0.00170   1.00000   0.01430
O3   0.84080   0.47580   0.24460   1.00000   0.02020
O4   0.84570   0.48260   0.78590   1.00000   0.01640
O5   0.78010   0.71440   0.84170   1.00000   0.00770
O6   0.78660   0.73960   0.18620   1.00000   0.01970