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 = 7.4 GPa ; _database_code_amcsd 0018350 _chemical_compound_source 'Ellora Caves, India' _chemical_formula_sum 'Si O2' _cell_length_a 7.894 _cell_length_b 4.456 _cell_length_c 8.582 _cell_angle_alpha 90 _cell_angle_beta 119.7 _cell_angle_gamma 90 _cell_volume 262.220 _exptl_crystal_density_diffrn 3.044 _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 0.62740 0.27670 0.84920 0.00800 Si2 0.87570 0.98750 0.72600 0.01100 O1 0.81070 0.10820 0.86800 0.00800 O2 0.68890 0.44900 0.03330 0.01700 O3 0.45340 0.03380 0.80430 0.01600 O4 0.06890 0.13820 0.75040 0.01400