data_global _chemical_name_mineral 'Polyhalite' loop_ _publ_author_name 'Bindi L' _journal_name_full 'Acta Crystallographica, Section E' _journal_volume 61 _journal_year 2005 _journal_page_first i135 _journal_page_last i136 _publ_section_title ; Reinvestigation of the crystal structure of polyhalite, K2Ca2Mg(SO4)4*2H2O ; _database_code_amcsd 0010450 _chemical_formula_sum 'K2 Ca2 Mg S4 O18 H4' _cell_length_a 6.975 _cell_length_b 6.984 _cell_length_c 8.899 _cell_angle_alpha 104.01 _cell_angle_beta 101.19 _cell_angle_gamma 114.10 _cell_volume 362.337 _exptl_crystal_density_diffrn 2.763 _symmetry_space_group_name_H-M 'P -1' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,-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 0.52448 0.78828 0.57178 0.02290 Ca 0.12539 0.36459 -0.25711 0.01460 Mg 0.00000 0.00000 0.00000 0.01530 S1 0.31293 0.56434 0.14152 0.01250 S2 -0.05661 0.18567 0.35769 0.01310 O1 -0.03700 0.00820 0.23690 0.01740 O2 0.12840 0.33540 0.03870 0.02200 O3 0.49860 0.55400 0.24150 0.02020 O4 -0.23440 0.31000 0.75170 0.01890 O5 0.37820 0.67210 0.02220 0.02160 O6 -0.17280 0.27860 0.26870 0.01880 O7 -0.17780 0.08440 0.46010 0.02110 O8 0.16770 0.36100 0.46800 0.02230 Wat9 0.31070 0.04320 0.08290 0.01520 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 K 0.01990 0.02440 0.02270 0.01000 0.00700 0.00670 Ca 0.01320 0.01440 0.01620 0.00670 0.00490 0.00520 Mg 0.01400 0.01520 0.01380 0.00650 0.00300 0.00280 S1 0.01210 0.01270 0.01250 0.00650 0.00440 0.00280 S2 0.01440 0.01250 0.01240 0.00730 0.00450 0.00300 O1 0.02460 0.01580 0.01380 0.01260 0.00660 0.00310 O2 0.01870 0.01530 0.02390 0.00650 0.00190 0.00070 O3 0.01860 0.02320 0.01720 0.01140 0.00330 0.00380 O4 0.01720 0.02030 0.01560 0.00860 0.00570 0.00100 O5 0.02530 0.02110 0.02000 0.01150 0.00940 0.00770 O6 0.02130 0.01900 0.01860 0.01290 0.00450 0.00650 O7 0.02290 0.02230 0.02190 0.01070 0.01180 0.01080 O8 0.01680 0.01980 0.01910 0.00520 0.00030 -0.00020 Wat9 0.01320 0.01350 0.02440 0.00830 0.01030 0.00900