data_global _chemical_name_mineral 'Pigeonite' loop_ _publ_author_name 'Angel R J' 'McCammon C A' 'Woodland A B' _journal_name_full 'Physics and Chemistry of Minerals' _journal_volume 25 _journal_year 1998 _journal_page_first 249 _journal_page_last 258 _publ_section_title ; Structure, ordering and cation interactions in Ca-free P2_1/c clinopyroxenes Sample: H162 Note: x coordinate of O2B changed by author, May, 2004 ; _database_code_amcsd 0008137 _chemical_formula_sum '(Mg.61 Fe.39) Si O3' _cell_length_a 9.6519 _cell_length_b 8.9075 _cell_length_c 5.2004 _cell_angle_alpha 90 _cell_angle_beta 108.590 _cell_angle_gamma 90 _cell_volume 423.773 _exptl_crystal_density_diffrn 3.533 _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_occupancy _atom_site_U_iso_or_equiv MgM1 0.25120 0.65390 0.22010 0.77900 0.01279 FeM1 0.25120 0.65390 0.22010 0.22100 0.01279 MgM2 0.25700 0.01530 0.22020 0.44100 0.01621 FeM2 0.25700 0.01530 0.22020 0.55900 0.01621 SiA 0.04310 0.34010 0.28990 1.00000 0.01001 SiB 0.55310 0.83590 0.23540 1.00000 0.00925 O1A 0.86910 0.33760 0.18210 1.00000 0.01229 O1B 0.37500 0.83880 0.12870 1.00000 0.00912 O2A 0.12390 0.49930 0.32830 1.00000 0.01026 O2B 0.63440 0.98190 0.38690 1.00000 0.01532 O3A 0.10470 0.27290 0.60530 1.00000 0.01406 O3B 0.60480 0.70060 0.46250 1.00000 0.01254 loop_ _atom_site_aniso_label _atom_site_aniso_U_11 _atom_site_aniso_U_22 _atom_site_aniso_U_33 _atom_site_aniso_U_12 _atom_site_aniso_U_13 _atom_site_aniso_U_23 MgM1 0.01102 0.01045 0.01539 -0.00413 0.00228 -0.00222 FeM1 0.01102 0.01045 0.01539 -0.00413 0.00228 -0.00222 MgM2 0.01569 0.01809 0.01415 -0.00248 0.00320 -0.00334 FeM2 0.01569 0.01809 0.01415 -0.00248 0.00320 -0.00334 SiA 0.00933 0.01125 0.00997 0.00041 0.00366 -0.00044 SiB 0.00763 0.01005 0.01009 -0.00083 0.00297 -0.00178 O1A 0.01696 0.01527 0.00591 -0.00454 0.00571 -0.00222 O1B 0.00721 0.00965 0.00775 0.00124 -0.00160 -0.00400 O2A 0.01018 0.00884 0.01022 -0.00041 0.00114 0.00334 O2B 0.01272 0.01286 0.01908 -0.00248 0.00343 0.00712 O3A 0.01357 0.01568 0.01022 0.00000 -0.00091 0.00089 O3B 0.01060 0.01206 0.01637 0.00330 0.00594 0.00067