data_global _chemical_name_mineral 'Gypsum' loop_ _publ_author_name 'Schofield P F' 'Knight K S' 'Stretton I C' _journal_name_full 'American Mineralogist' _journal_volume 81 _journal_year 1996 _journal_page_first 847 _journal_page_last 851 _publ_section_title ; Thermal expansion of gypsum investigated by neutron powder diffraction T = 4.2 K ; _database_code_amcsd 0001807 _chemical_formula_sum 'Ca S O6 D4' _cell_length_a 5.6740 _cell_length_b 15.1049 _cell_length_c 6.4909 _cell_angle_alpha 90 _cell_angle_beta 118.513 _cell_angle_gamma 90 _cell_volume 488.829 _exptl_crystal_density_diffrn 2.394 _symmetry_space_group_name_H-M 'I 1 2/a 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,1/2+z' '-x,y,1/2-z' '1/2-x,1/2+y,-z' '1/2+x,1/2-y,z' '+x,-y,1/2+z' '1/2-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_U_iso_or_equiv Ca 0.50000 0.07996 0.25000 0.00124 S 0.00000 0.07667 0.75000 0.00132 O1 0.96413 0.13282 0.55028 0.00376 O2 0.75763 0.02194 0.66427 0.00355 Ow 0.38342 0.17240 0.46179 0.00403 D1 0.25369 0.16662 0.50769 0.01809 D2 0.40549 0.24481 0.49322 0.01631