data_global _chemical_name_mineral 'Pargasite' loop_ _publ_author_name 'Welch M D' 'Knight K S' _journal_name_full 'European Journal of Mineralogy' _journal_volume 11 _journal_year 1999 _journal_page_first 321 _journal_page_last 331 _publ_section_title ; A neutron powder diffraction study of cation ordering in high-temperature synthetic amphiboles ; _database_code_amcsd 0006771 _chemical_formula_sum 'Na Mg4 Al3 Ca2 Si6 O24 H2' _cell_length_a 9.8930 _cell_length_b 17.937 _cell_length_c 5.2802 _cell_angle_alpha 90 _cell_angle_beta 105.518 _cell_angle_gamma 90 _cell_volume 902.819 _exptl_crystal_density_diffrn 3.075 _symmetry_space_group_name_H-M 'C 1 2/m 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,z' '1/2+x,1/2-y,z' '-x,y,-z' '1/2-x,1/2+y,-z' '-x,-y,-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_occupancy _atom_site_U_iso_or_equiv NaA2/m 0.00000 0.50000 0.00000 1.00000 0.06800 MgM1 0.00000 0.08810 0.50000 1.00000 0.00570 MgM2 0.00000 0.17610 0.00000 0.75000 0.00110 AlM2 0.00000 0.17610 0.00000 0.25000 0.00110 MgM3 0.00000 0.00000 0.00000 0.50000 0.00670 AlM3 0.00000 0.00000 0.00000 0.50000 0.00670 CaM4 0.00000 0.28040 0.50000 1.00000 0.01040 SiT1 0.28070 0.08610 0.30400 0.58000 0.00230 AlT1 0.28070 0.08610 0.30400 0.42000 0.00230 SiT2 0.28840 0.17340 0.81710 0.92000 0.00250 AlT2 0.28840 0.17340 0.81710 0.08000 0.00250 O1 0.10700 0.08660 0.21850 1.00000 0.00930 O2 0.11990 0.17260 0.73300 1.00000 0.00780 O3 0.10610 0.00000 0.71760 1.00000 0.00100 O4 0.36580 0.25060 0.78630 1.00000 0.00720 O5 0.34890 0.13990 0.11650 1.00000 0.00590 O6 0.34360 0.11350 0.61910 1.00000 0.00890 O7 0.34140 0.00000 0.26720 1.00000 0.00830 H 0.20450 0.00000 0.77960 1.00000 0.04500