data_global _chemical_name_mineral 'Demartinite' loop_ _publ_author_name 'Gramaccioli C M' 'Campostrini I' _journal_name_full 'The Canadian Mineralogist' _journal_volume 45 _journal_year 2007 _journal_page_first 1275 _journal_page_last 1280 _publ_section_title ; Demartinite, a new polymorph of K2SiF6 from La Fossa Crater, Vulcano, Aeolian Islands, Italy ; _database_code_amcsd 0006157 _chemical_compound_source 'La Fossa Crater, Vulcano Island, Aeolian Archipelago, Sicily, Italy' _chemical_formula_sum 'K2 Si F6' _cell_length_a 5.6461 _cell_length_b 5.6461 _cell_length_c 9.2322 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 254.878 _exptl_crystal_density_diffrn 2.870 _symmetry_space_group_name_H-M 'P 63 m c' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,-x+y,1/2+z' 'x-y,x,1/2+z' '-y,-x,z' '-y,x-y,z' 'x-y,-y,1/2+z' '-x,-y,1/2+z' 'x,x-y,z' '-x+y,-x,z' 'y,x,1/2+z' 'y,-x+y,1/2+z' '-x+y,y,z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z K1 0.66667 0.33333 0.09275 K2 0.00000 0.00000 0.81199 Si 0.33333 0.66667 0.97559 F1 0.61751 0.80875 0.07798 F2 0.05287 0.52644 0.86889 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 K1 0.01880 0.01880 0.02100 0.00940 0.00000 0.00000 K2 0.02440 0.02440 0.02940 0.01220 0.00000 0.00000 Si 0.01340 0.01340 0.01420 0.00670 0.00000 0.00000 F1 0.01850 0.02420 0.02480 0.00930 -0.00790 -0.00400 F2 0.01840 0.02600 0.02400 0.00920 -0.00680 -0.00340