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 = 4.130 GPa
;
_database_code_amcsd 0004425
_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 9.7178
_cell_length_b 9.7178
_cell_length_c 8.2030
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 120
_cell_volume 670.871
_exptl_crystal_density_diffrn      2.837
_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   0.01900
NaK   0.00000   0.00000   0.00410   0.24000   0.01900
CaK   0.00000   0.00000   0.00410   0.03000   0.01900
Na   0.55760   0.99930   0.50640   1.00000   0.01820
AlT1   0.66667   0.33333   0.71222   1.00000   0.00870
SiT2   0.66667   0.33333   0.31158   1.00000   0.00750
SiT3   0.91817   0.67174   0.82475   1.00000   0.00910
AlT4   0.91775   0.67115   0.19370   1.00000   0.00750
O1   0.66667   0.33333   0.50590   1.00000   0.04060
O2   0.00071   0.69849   0.00420   1.00000   0.01440
O3   0.83360   0.47374   0.23100   1.00000   0.02070
O4   0.84560   0.48771   0.76420   1.00000   0.01660
O5   0.77691   0.71442   0.83450   1.00000   0.01260
O6   0.78500   0.73920   0.18750   1.00000   0.01350