data_global
_chemical_name_mineral 'Weberite'
loop_
_publ_author_name
'Knop O'
'Cameron T S'
'Jochem K'
_journal_name_full 'Journal of Solid State Chemistry'
_journal_volume 43 
_journal_year 1982
_journal_page_first 213
_journal_page_last 221
_publ_section_title
;
 What is the true space group of weberite?
 Sample: I2_12_12_1 refinement, T = ambient
 Note: y(F6) and z(F6) corrected
;
_database_code_amcsd 0013481
_chemical_compound_source 'Ivigtut, Greenland'
_chemical_formula_sum 'Na2 Mg Al F7'
_cell_length_a 7.051
_cell_length_b 9.968
_cell_length_c 7.285
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 512.022
_exptl_crystal_density_diffrn      2.987
_symmetry_space_group_name_H-M 'I 21 21 21'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '1/2+x,1/2+y,1/2+z'
  '-x,1/2+y,1/2-z'
  '1/2-x,+y,-z'
  '1/2+x,-y,-z'
  '+x,1/2-y,1/2-z'
  '1/2-x,1/2-y,1/2+z'
  '-x,-y,+z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
Na1   0.25000   0.00030   0.50000
Na2  -0.00270   0.25000   0.75000
Mg   0.25000   0.00060   0.00000
Al   0.00000   0.25000   0.25000
F1   0.00000   0.00000   0.88630
F3  -0.00160   0.16480   0.47090
F5   0.18300   0.13590   0.18180
F6   0.31500   0.63880   0.67910
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
Na1 0.01770 0.01920 0.05530 0.00000 -0.00450 0.00000
Na2 0.02190 0.03330 0.01490 0.00000 0.00000 0.00950
Mg 0.00740 0.00630 0.00710 0.00000 -0.00080 0.00000
Al 0.00780 0.00700 0.00750 0.00000 0.00000 -0.00180
F1 0.00780 0.01910 0.01270 -0.00290 0.00000 0.00000
F3 0.01840 0.01590 0.00950 0.00350 0.00040 0.00140
F5 0.01450 0.01280 0.01800 0.00980 0.00090 -0.00610
F6 0.01150 0.01350 0.01550 -0.00320 0.00250 -0.00830