data_global
_chemical_name_mineral 'Polyhalite'
loop_
_publ_author_name
'Schlatti M'
'Sahl K'
'Zemann A'
'Zemann J'
_journal_name_full 'Tschermaks Mineralogische und Petrographische Mitteilungen'
_journal_volume 14 
_journal_year 1970
_journal_page_first 75
_journal_page_last 86
_publ_section_title
;
 Die kristallstruktur des polyhalits, K2Ca2Mg(SO4)4(H2O)2
;
_database_code_amcsd 0015636
_chemical_formula_sum 'K2 Ca2 Mg S4 O18 H4'
_cell_length_a 11.69
_cell_length_b 16.330
_cell_length_c 7.60
_cell_angle_alpha 91.6
_cell_angle_beta 90.0
_cell_angle_gamma 91.9
_cell_volume 1449.459
_exptl_crystal_density_diffrn      2.763
_symmetry_space_group_name_H-M 'F -1'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  'x,1/2+y,1/2+z'
  '1/2+x,y,1/2+z'
  '1/2+x,1/2+y,z'
  '-x,-y,-z'
  '-x,1/2-y,1/2-z'
  '1/2-x,-y,1/2-z'
  '1/2-x,1/2-y,-z'
loop_
_atom_site_label
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_U_iso_or_equiv
K   0.13189   0.28615   0.63004   0.01646
Ca   0.11914   0.37120   0.12619   0.01013
Mg   0.00000   0.00000   0.00000   0.00950
S1   0.12582   0.07054   0.63225   0.00823
S2   0.12061   0.17896   0.11415   0.00861
O1   0.02782   0.12014   0.59472   0.01900
O2   0.22760   0.12428   0.66306   0.01317
O3   0.10304   0.01950   0.78843   0.01431
O4   0.14787   0.01101   0.48555   0.01710
O5   0.13167   0.22955   0.27763   0.01710
O6   0.09617   0.23414   0.96862   0.01697
O7   0.02245   0.11814   0.13130   0.01558
O8   0.22550   0.13457   0.08081   0.01431
Wat9   0.13515   0.45748   0.63492   0.01343