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 = 133 K
 Note: y(F6) and z(F6) corrected
;
_database_code_amcsd 0013482
_chemical_compound_source 'Ivigtut, Greenland'
_chemical_formula_sum 'Na2 Mg Al F7'
_cell_length_a 7.050
_cell_length_b 9.979
_cell_length_c 7.297
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 513.358
_exptl_crystal_density_diffrn      2.979
_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   0.00010   0.50000
Na2  -0.00040   0.25000   0.75000
Mg   0.25000   0.00030   0.00000
Al  -0.00110   0.25000   0.25000
F1   0.00000   0.00000   0.88610
F3  -0.00010   0.16440   0.47130
F5   0.18380   0.13620   0.18180
F6   0.31480   0.63850   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 0.01190 0.01220 0.04400 0.00000 -0.00290 0.00000
Na2 0.01480 0.02510 0.01200 0.00000 0.00000 0.00690
Mg 0.00480 0.00480 0.00760 0.00000 0.00050 0.00000
Al 0.00560 0.00500 0.00760 0.00000 0.00000 -0.00100
F1 0.00620 0.01430 0.01160 0.00000 0.00000 0.00000
F3 0.01230 0.01090 0.01020 0.00000 -0.00200 0.00030
F5 0.00830 0.01040 0.01660 -0.00120 -0.00010 -0.00330
F6 0.01030 0.00850 0.01180 0.00530 0.00320 -0.00380