data_global
_chemical_name_mineral 'NH4Cr(SO4)2*12H2O'
loop_
_publ_author_name
'Rempfer N'
'Lerner H W'
'Bolte M'
_journal_name_full 'Acta Crystallographica, Section E'
_journal_volume 60 
_journal_year 2004
_journal_page_first i80
_journal_page_last i81
_publ_section_title
;
 The ammonium chromium(III) alum NH4Cr(SO4)2*12H2O
;
_chemical_formula_sum 'N H28 Cr S2 O20'
_cell_length_a 12.2491
_cell_length_b 12.2491
_cell_length_c 12.2491
_cell_angle_alpha 90
_cell_angle_beta 90
_cell_angle_gamma 90
_cell_volume 1837.860
_exptl_crystal_density_diffrn      1.729
_symmetry_space_group_name_H-M 'P a 3'
loop_
_symmetry_equiv_pos_as_xyz
  'x,y,z'
  '1/2+z,x,1/2-y'
  'z,1/2-x,1/2+y'
  '1/2-z,1/2+x,y'
  '-z,-x,-y'
  '1/2+y,1/2-z,-x'
  '1/2-y,-z,1/2+x'
  '-y,1/2+z,1/2-x'
  'y,z,x'
  'x,1/2-y,1/2+z'
  '1/2-x,1/2+y,z'
  '1/2+x,y,1/2-z'
  '-x,-y,-z'
  '1/2-z,-x,1/2+y'
  '-z,1/2+x,1/2-y'
  '1/2+z,1/2-x,-y'
  'z,x,y'
  '1/2-y,1/2+z,x'
  '1/2+y,z,1/2-x'
  'y,1/2-z,1/2+x'
  '-y,-z,-x'
  '-x,1/2+y,1/2-z'
  '1/2+x,1/2-y,-z'
  '1/2-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
N   0.00000   0.50000   0.50000   1.00000   0.03230
H1   0.01200   0.54400   0.55300   0.66667   0.03900
Cr   0.50000   0.50000   0.50000   1.00000   0.00994
S   0.80864   0.69136   0.30864   1.00000   0.01273
O1   0.81058   0.73618   0.41998   1.00000   0.02520
O2   0.73931   0.76069   0.23931   1.00000   0.03400
O3   0.48764   0.51483   0.34114   1.00000   0.01480
H3A   0.47080   0.57120   0.31310   1.00000   0.03500
H3B   0.48030   0.46260   0.29830   1.00000   0.03600
O4   0.04676   0.63817   0.69723   1.00000   0.02200
H4A   0.00750   0.68290   0.70820   1.00000   0.02600
H4B   0.10400   0.66630   0.70850   1.00000   0.03900
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
N 0.03230 0.03230 0.03230 -0.01600 0.01600 -0.01600
Cr 0.00994 0.00994 0.00994 -0.00036 -0.00036 -0.00036
S 0.01273 0.01273 0.01273 -0.00183 0.00183 -0.00183
O1 0.02190 0.03480 0.01900 -0.01110 0.00420 -0.01260
O2 0.03400 0.03400 0.03400 0.00850 -0.00850 0.00850
O3 0.01970 0.01340 0.01140 0.00130 -0.00160 -0.00030
O4 0.02050 0.01880 0.02660 0.00380 0.00600 0.00580