data_global _chemical_name_mineral 'Quartz' loop_ _publ_author_name 'Hazen R M' 'Finger L W' 'Hemley R J' 'Mao H K' _journal_name_full 'Solid State Communications' _journal_volume 72 _journal_year 1989 _journal_page_first 507 _journal_page_last 511 _publ_section_title ; High-pressure crystal chemistry and amorphization of alpha-quartz Sample: P = 5.1 GPa ; _database_code_amcsd 0015464 _chemical_compound_source 'Synthetic' _chemical_formula_sum 'Si O2' _cell_length_a 4.705 _cell_length_b 4.705 _cell_length_c 5.250 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 100.649 _exptl_crystal_density_diffrn 2.974 _symmetry_space_group_name_H-M 'P 31 2 1' loop_ _space_group_symop_operation_xyz 'x,y,z' 'y,x,-z' '-y,x-y,1/3+z' '-x,-x+y,1/3-z' '-x+y,-x,2/3+z' 'x-y,-y,2/3-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv Si 0.45320 0.00000 0.33333 0.00646 O 0.39300 0.28810 0.23400 0.01089