data_global _chemical_name_mineral 'Pigeonite' loop_ _publ_author_name 'Clark J R' 'Ross M' 'Appleman D E' _journal_name_full 'American Mineralogist' _journal_volume 56 _journal_year 1971 _journal_page_first 888 _journal_page_last 908 _publ_section_title ; Crystal chemistry of a lunar pigeonite class b data refinement ; _database_code_amcsd 0000248 _chemical_formula_sum '(Mg.54 Fe.46) Si O3' _cell_length_a 9.678 _cell_length_b 8.905 _cell_length_c 5.227 _cell_angle_alpha 90 _cell_angle_beta 108.71 _cell_angle_gamma 90 _cell_volume 426.671 _exptl_crystal_density_diffrn 3.577 _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 Mg1 0.25060 0.65480 0.23000 0.67000 0.00697 Fe1 0.25060 0.65480 0.23000 0.33000 0.00697 Mg2 0.25640 0.01670 0.22460 0.41000 0.00646 Fe2 0.25640 0.01670 0.22460 0.59000 0.00646 SiA 0.04340 0.33990 0.28440 1.00000 0.00507 SiB 0.55200 0.83640 0.23680 1.00000 0.00431 O1A 0.86840 0.33730 0.17400 1.00000 0.00722 O1B 0.37550 0.83570 0.12960 1.00000 0.00545 O2A 0.12310 0.49770 0.33120 1.00000 0.00988 O2B 0.63140 0.98500 0.38140 1.00000 0.00747 O3A 0.10480 0.26830 0.59170 1.00000 0.01418 O3B 0.60450 0.70470 0.47070 1.00000 0.01330 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 Mg2 0.00724 0.00723 0.00472 0.00124 0.00138 0.00089 Fe2 0.00724 0.00723 0.00472 0.00124 0.00138 0.00089 O3A 0.00936 0.02169 0.01180 0.00000 0.00368 0.00737 O3B 0.00936 0.01768 0.01366 0.00289 0.00506 0.00581