data_global _chemical_name_mineral 'Cristobalite II' loop_ _publ_author_name 'Dera P' 'Lazarz J D' 'Prakapenka V B' 'Barkley M' 'Downs R T' _journal_name_full 'Physics and Chemistry of Minerals' _journal_volume 38 _journal_year 2011 _journal_page_first 517 _journal_page_last 529 _publ_section_title ; New insights into the high-pressure polymorphism of SiO2 cristobalite Note: P = 4.9 GPa Note z-coordinate of O2 is corrected ; _database_code_amcsd 0018349 _chemical_compound_source 'Ellora Caves, India' _chemical_formula_sum 'Si O2' _cell_length_a 8.011 _cell_length_b 4.544 _cell_length_c 8.890 _cell_angle_alpha 90 _cell_angle_beta 121.0 _cell_angle_gamma 90 _cell_volume 277.391 _exptl_crystal_density_diffrn 2.877 _symmetry_space_group_name_H-M 'P 1 21/c 1' 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' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv Si1 0.62650 0.27420 0.84720 0.01100 Si2 0.87570 0.00790 0.72180 0.01400 O1 0.81100 0.11220 0.86060 0.01500 O2 0.69800 0.42610 0.03300 0.01900 O3 0.46360 0.03260 0.80420 0.01100 O4 0.06650 0.17040 0.75330 0.01600