data_global _chemical_name_mineral 'Vermiculite' loop_ _publ_author_name 'Hendricks S B' 'Jefferson M E' _journal_name_full 'American Mineralogist' _journal_volume 23 _journal_year 1938 _journal_page_first 851 _journal_page_last 862 _publ_section_title ; Crystal structure of vermiculites and mixed vermiculite-chlorites ; _database_code_amcsd 19 _chemical_formula_sum 'Mg3 (O12 Si4) H2' _cell_length_a 5.33 _cell_length_b 9.18 _cell_length_c 28.85 _cell_angle_alpha 90.0 _cell_angle_beta 93.25 _cell_angle_gamma 90.0 _cell_volume 1409.343 _exptl_crystal_density_diffrn 1.787 _symmetry_space_group_name_H-M 'C 1 c 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Mg1 0.0 0.0 0.0 Mg2 0.0 0.333333 0.0 Mg3 0.0 0.666667 0.0 O-H1 0.18 0.5 0.04 O-H2 -0.18 0.83333 -0.04 O1 0.18 0.83333 0.04 O2 -0.18 0.5 -0.04 O3 0.18 0.16667 0.04 O4 -0.18 0.16667 -0.04 O5 -0.048 0.75 0.115 O6 0.048 0.5833 -0.115 O7 0.452 0.75 0.115 O8 -0.452 0.5833 -0.115 O9 0.202 0.0 0.115 O10 -0.202 0.333333 -0.115 Si1 0.196 0.83333 0.095 Si2 -0.196 0.5 -0.095 Si3 -0.304 0.666667 0.095 Si4 0.304 0.666667 -0.095