data_global _chemical_name_mineral 'Prehnite' loop_ _publ_author_name 'Papike J J' 'Zoltai T' _journal_name_full 'American Mineralogist' _journal_volume 52 _journal_year 1967 _journal_page_first 974 _journal_page_last 984 _publ_section_title ; Ordering of tetrahedral aluminium in prehnite, Ca2(Al,Fe)[Si3AlO10](OH)2 ; _database_code_amcsd 0000157 _chemical_formula_sum 'Ca2 Al2 Si3 O12 H2' _cell_length_a 4.646 _cell_length_b 5.483 _cell_length_c 18.486 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 470.913 _exptl_crystal_density_diffrn 2.908 _symmetry_space_group_name_H-M 'P n c m' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,1/2+y,1/2+z' 'x,1/2-y,1/2-z' 'x,y,-z' '-x,-y,z' 'x,1/2-y,1/2+z' '-x,1/2+y,1/2-z' '-x,-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 Ca 0.00000 0.50000 0.09920 1.00000 0.00519 Al 0.00000 0.00000 0.00000 1.00000 0.00329 Si1 0.50000 0.00000 0.11950 1.00000 0.00317 Si2 0.18950 0.25000 0.25000 0.50000 0.00253 Al2 0.18950 0.25000 0.25000 0.50000 0.00253 O1 0.75110 0.13230 0.07390 1.00000 0.00570 O2 0.36860 0.21300 0.17160 1.00000 0.00747 O3 0.00000 0.00000 0.26870 1.00000 0.01963 O-H 0.20540 0.30180 0.00000 1.00000 0.00861