data_global _chemical_name_mineral 'Talc' loop_ _publ_author_name 'Drits V A' 'Guggenheim S' 'Zviagina B B' 'Kogure T' _journal_name_full 'Clays and Clay Minerals' _journal_volume 60 _journal_year 2012 _journal_page_first 574 _journal_page_last 587 _publ_section_title ; Structures of the 2:1 layers of pyrophyllite and talc Note: structure is averaged to remove stacking disorder effects ; _database_code_amcsd 0020723 _chemical_compound_source 'Harford County, Maryland, USA' _chemical_formula_sum 'Mg3 Si4 O12 H2' _cell_length_a 5.1848 _cell_length_b 8.9230 _cell_length_c 9.19 _cell_angle_alpha 90.69 _cell_angle_beta 90.9 _cell_angle_gamma 90 _cell_volume 425.083 _exptl_crystal_density_diffrn 2.963 _symmetry_space_group_name_H-M 'C -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' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Mg1 0.00000 0.00000 0.00000 Mg2 0.50000 0.16659 0.00000 Si1 0.83367 0.16683 0.29100 Si2 0.33367 0.33317 0.29100 O1 0.33361 0.33303 0.11760 O2 0.83361 0.16698 0.11760 O-h1 0.33297 0.00000 0.11260 Ob1 0.35160 0.50000 0.34810 Ob2 0.57486 0.24099 0.34890 Ob3 0.07485 0.25901 0.34890 H 0.33302 0.00153 0.20300