data_global _chemical_name_mineral 'Cristobalite' loop_ _publ_author_name 'Matsui M' 'Sato T' 'Funamori N' _journal_name_full 'American Mineralogist' _journal_volume 99 _journal_year 2014 _journal_page_first 184 _journal_page_last 189 _publ_section_title ; Crystal structures and stabilities of cristobalite-helium phases at high pressures Note: P = 10 GPa ; _database_code_amcsd 0020170 _chemical_compound_source 'calculated structure' _chemical_formula_sum 'Si O2 He' _cell_length_a 8.062 _cell_length_b 4.797 _cell_length_c 9.491 _cell_angle_alpha 90 _cell_angle_beta 120.43 _cell_angle_gamma 90 _cell_volume 316.488 _exptl_crystal_density_diffrn 2.690 _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 Si1 0.62340 0.38830 0.83820 Si2 0.87260 0.12150 0.71190 O1 0.80010 0.26410 0.82490 O2 0.69100 0.41210 0.02930 O3 0.43540 0.19120 0.74770 O4 0.03730 0.31840 0.71460 He1 0.63280 0.59350 0.53200 He2 0.13790 0.33150 0.51360