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