Reinvestigation of the crystal structure of polyhalite, K~2~Ca~2~Mg(SO~4~)~4~.2H~2~O
Bindi, Luca; Acta Crystallographica, Section E 61 (2005) i135–i136; doi:10.1107/S1600536805020507

data_2206573
_publ_section_title
;
Reinvestigation of the crystal structure of polyhalite,
K~2~Ca~2~Mg(SO~4~)~4~.2H~2~O
;
_journal_issue                   8
_journal_name_full               'Acta Crystallographica, Section E'
_journal_page_first              i135
_journal_page_last               i136
_journal_paper_doi               10.1107/S1600536805020507
_journal_volume                  61
_journal_year                    2005
_chemical_formula_iupac          'K2 Ca2 Mg (S O4)4, 2H2 O'
_chemical_formula_structural     'K2 Ca2 Mg (S O4)4, 2H2 O'
_chemical_formula_sum            'Ca2 H4 K2 Mg O18 S4'
_chemical_formula_weight         602.92
_chemical_name_common            Polyhalite
_chemical_name_systematic
;
Dipotassium Dicalcium Magnesium Tetrakis[sulfate(VI)] Dihydrate
;
_space_group_IT_number           2
_space_group_name_Hall           '-P 1'
_space_group_name_H-M_alt        'P -1'
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_cell_angle_alpha                104.01(3)
_cell_angle_beta                 101.19(3)
_cell_angle_gamma                114.10(6)
_cell_formula_units_Z            1
_cell_length_a                   6.975(3)
_cell_length_b                   6.984(3)
_cell_length_c                   8.899(3)
_cell_measurement_reflns_used    1206
_cell_measurement_temperature    298(2)
_cell_measurement_theta_max      26.4
_cell_measurement_theta_min      10.2
_cell_volume                     362.3(4)
_computing_cell_refinement       'CrysAlis CCD'
_computing_data_collection       'CrysAlis CCD (Oxford Diffraction, 2002)'
_computing_data_reduction        'CrysAlis RED (Oxford Diffraction, 2002)'
_computing_molecular_graphics
;
XTAL--DRAW (Downs & Hall-Wallace, 2003) and ORTEP-3 for Windows
(Farrugia, 1997)
;
_computing_publication_material  SHELXL97
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      298(2)
_diffrn_measured_fraction_theta_full 0.955
_diffrn_measured_fraction_theta_max 0.649
_diffrn_measurement_device_type  'Oxford Diffraction Xcalibur-3'
_diffrn_measurement_method       \w
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0246
_diffrn_reflns_av_sigmaI/netI    0.0281
_diffrn_reflns_limit_h_max       6
_diffrn_reflns_limit_h_min       -9
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       -7
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -10
_diffrn_reflns_number            2629
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         31.26
_diffrn_reflns_theta_min         4.22
_diffrn_standards_decay_%        0
_diffrn_standards_interval_count 0
_diffrn_standards_interval_time  0
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    2.087
_exptl_absorpt_correction_T_max  0.5098
_exptl_absorpt_correction_T_min  0.4925
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   '(DENZO-SMN; Otwinowski & Minor, 1997)'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    2.763
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       prism
_exptl_crystal_F_000             302
_exptl_crystal_size_max          0.35
_exptl_crystal_size_mid          0.33
_exptl_crystal_size_min          0.32
_refine_diff_density_max         1.194
_refine_diff_density_min         -0.680
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.967
_refine_ls_hydrogen_treatment    undef
_refine_ls_matrix_type           full
_refine_ls_number_parameters     124
_refine_ls_number_reflns         1525
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.967
_refine_ls_R_factor_all          0.0540
_refine_ls_R_factor_gt           0.0476
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=  1/[\s^2^(Fo^2^)+(0.0856P)^2^+1.9844P] where P = (Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1379
_refine_ls_wR_factor_ref         0.1430
_reflns_number_gt                1305
_reflns_number_total             1525
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            wm6074.cif
_cod_depositor_comments
;
 Marking attached hydrogen atoms.

 Antanas Vaitkus,
 2017-11-23
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_cod_original_formula_sum        'Ca2 H4 K2 Mg1 O18 S4'
_cod_database_code               2206573