data_global _chemical_name_mineral 'Seifertite' loop_ _publ_author_name 'Dera P' 'Prewitt C T' 'Boctor N Z' 'Hemley R J' _journal_name_full 'American Mineralogist' _journal_volume 87 _journal_year 2002 _journal_page_first 1018 _journal_page_last 1023 _publ_section_title ; Characterization of a high-pressure phase of silica from the Martian meteorite Shergotty alpha-PbO2-like ; _database_code_amcsd 0002871 _chemical_formula_sum 'Si O2' _cell_length_a 4.097 _cell_length_b 5.0462 _cell_length_c 4.4946 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 92.923 _exptl_crystal_density_diffrn 4.295 _symmetry_space_group_name_H-M 'P b c n' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,-y,1/2+z' '-x,y,1/2-z' '1/2-x,1/2+y,z' '1/2+x,1/2-y,-z' '1/2+x,1/2+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 Si 0.00000 0.15220 0.25000 0.01013 O 0.73360 0.62450 0.91860 0.00127