data_global _chemical_name_mineral 'Pyroxene-ideal' loop_ _publ_author_name 'Thompson R M' 'Downs R T' _journal_name_full 'American Mineralogist' _journal_volume 89 _journal_year 2004 _journal_page_first 614 _journal_page_last 628 _publ_section_title ; Model pyroxenes II: Structural variation as a function of tetrahedral rotation model zinc px after Morimoto et al. (1975) with O3-O3-O3 angle = 161.3 and model oxygen radius = 1.329 ; _database_code_amcsd 0003507 _chemical_formula_sum 'Zn Si O3' _cell_length_a 9.755 _cell_length_b 9.083 _cell_length_c 5.244 _cell_angle_alpha 90 _cell_angle_beta 107.9 _cell_angle_gamma 90 _cell_volume 442.152 _exptl_crystal_density_diffrn 4.251 _symmetry_space_group_name_H-M 'C 1 2/c 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' '-x,y,1/2-z' '1/2-x,1/2+y,1/2-z' '-x,-y,-z' '1/2-x,1/2-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z Zn 0.00000 0.91667 0.25000 Zn 0.00000 0.25000 0.25000 Si 0.30840 0.08333 0.25960 O1 0.13310 0.08333 0.15940 O2 0.36690 0.25000 0.34060 O3 0.36690 0.02380 0.01930