data_global _chemical_name_mineral 'Amesite' loop_ _publ_author_name 'Steadman R' 'Nuttall P M' _journal_name_full 'Acta Crystallographica' _journal_volume 15 _journal_year 1962 _journal_page_first 510 _journal_page_last 511 _publ_section_title ; The crystal structure of amesite Note: polytype 6R ; _database_code_amcsd 0018742 _chemical_compound_source 'Saranovskaye, USSR' _chemical_formula_sum 'Mg2 Al2 Si O9 H4' _cell_length_a 5.31 _cell_length_b 5.31 _cell_length_c 42.1 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 1028.020 _exptl_crystal_density_diffrn 2.701 _symmetry_space_group_name_H-M 'R 3' loop_ _space_group_symop_operation_xyz 'x,y,z' '2/3+x,1/3+y,1/3+z' '1/3+x,2/3+y,2/3+z' '-y,x-y,z' '2/3-y,1/3+x-y,1/3+z' '1/3-y,2/3+x-y,2/3+z' '-x+y,-x,z' '2/3-x+y,1/3-x,1/3+z' '1/3-x+y,2/3-x,2/3+z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy MgY1 0.33300 0.00000 0.24500 0.66700 AlY1 0.33300 0.00000 0.24500 0.33300 MgY2 0.66700 0.00000 0.07800 0.66600 AlY2 0.66700 0.00000 0.07800 0.33400 SiX1 0.00000 0.00000 0.51400 0.50000 AlX1 0.00000 0.00000 0.51400 0.50000 SiX2 0.00000 0.00000 0.84700 0.50000 AlX2 0.00000 0.00000 0.84700 0.50000 SiX3 0.00000 0.00000 0.34700 0.50000 AlX3 0.00000 0.00000 0.34700 0.50000 SiX4 0.00000 0.00000 0.68100 0.50000 AlX4 0.00000 0.00000 0.68100 0.50000 O1 0.00000 0.00000 0.55400 1.00000 O2 0.00000 0.00000 0.88700 1.00000 O3 0.00000 0.00000 0.38700 1.00000 O4 0.00000 0.00000 0.72100 1.00000 O5 0.55000 0.00000 0.16700 1.00000 O6 0.45000 0.00000 0.00000 1.00000 O-H1 0.66700 0.00000 0.26900 1.00000 O-H2 0.33300 0.00000 0.10200 1.00000 O-H3 0.00000 0.00000 0.22100 1.00000 O-H4 0.00000 0.00000 0.05400 1.00000