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 = 320 K ; _database_code_amcsd 0001809 _chemical_formula_sum 'Ca S O6 D4' _cell_length_a 5.6769 _cell_length_b 15.2074 _cell_length_c 6.5277 _cell_angle_alpha 90 _cell_angle_beta 118.494 _cell_angle_gamma 90 _cell_volume 495.279 _exptl_crystal_density_diffrn 2.363 _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 0.07864 0.25000 0.00722 S 0.00000 0.07872 0.75000 0.00638 O1 0.96164 0.13263 0.55120 0.01491 O2 0.75714 0.02154 0.66527 0.01229 Ow 0.37837 0.18255 0.46544 0.02215 D1 0.25043 0.16150 0.50086 0.04458 D2 0.40225 0.24347 0.49003 0.03893