data_global _chemical_name_mineral 'Pigeonite' loop_ _publ_author_name 'Camara F' 'Carpenter M A' 'Domeneghetti M C' 'Tazzoli V' _journal_name_full 'American Mineralogist' _journal_volume 88 _journal_year 2003 _journal_page_first 1115 _journal_page_last 1128 _publ_section_title ; Coupling between non-convergent ordering and transition temperature in the C2/c - P2_1/c phase transition in pigeonite Sample: BTS-308 n.17-4, after heating at 800 deg C ; _database_code_amcsd 0003150 _chemical_compound_source 'Parana, Brazil' _chemical_formula_sum 'O6 Si2 Mg.93 Fe.829 Mn.027 Ca.193' _cell_length_a 9.707 _cell_length_b 8.943 _cell_length_c 5.246 _cell_angle_alpha 90 _cell_angle_beta 108.47 _cell_angle_gamma 90 _cell_volume 431.946 _exptl_crystal_density_diffrn 3.542 _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 O1A -0.13260 0.33860 0.17050 1.00000 0.00800 O1b 0.37380 0.83690 0.13410 1.00000 0.00800 O2A 0.12170 0.49950 0.33150 1.00000 0.01000 O2B 0.62940 0.98740 0.37410 1.00000 0.01300 O3A 0.10410 0.23700 0.08020 1.00000 0.01600 O3B 0.60490 0.70840 0.47910 1.00000 0.01300 SiA 0.04260 0.34040 0.27800 1.00000 0.00600 SiB 0.54970 0.83730 0.23800 1.00000 0.00600 MgM1 0.25050 0.65460 0.23070 0.71080 0.00600 FeM1 0.25050 0.65460 0.23070 0.26260 0.00600 MnM1 0.25050 0.65460 0.23070 0.00850 0.00600 CaM2 0.25540 0.01870 0.22830 0.19350 0.01100 MgM2 0.25540 0.01870 0.22830 0.21880 0.01100 FeM2 0.25540 0.01870 0.22830 0.56680 0.01100 MnM2 0.25540 0.01870 0.22830 0.01890 0.01100 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 O1A 0.00500 0.00900 0.00800 0.00000 0.00200 0.00000 O1b 0.00600 0.00900 0.00900 0.00100 0.00200 0.00000 O2A 0.01200 0.00700 0.01200 -0.00300 0.00500 -0.00100 O2B 0.01400 0.01100 0.01900 -0.00600 0.01000 -0.00700 O3A 0.00800 0.02100 0.01800 -0.00100 0.00400 0.00000 O3B 0.00700 0.01900 0.01200 0.00100 0.00300 0.00700 SiA 0.00500 0.00600 0.00800 -0.00100 0.00300 -0.00100 SiB 0.00600 0.00600 0.00700 -0.00100 0.00200 -0.00100 MgM1 0.00700 0.00600 0.00600 0.00000 0.00200 0.00000 FeM1 0.00700 0.00600 0.00600 0.00000 0.00200 0.00000 MnM1 0.00700 0.00600 0.00600 0.00000 0.00200 0.00000 CaM2 0.00900 0.01500 0.00700 0.00200 0.00100 0.00200 MgM2 0.00900 0.01500 0.00700 0.00200 0.00100 0.00200 FeM2 0.00900 0.01500 0.00700 0.00200 0.00100 0.00200 MnM2 0.00900 0.01500 0.00700 0.00200 0.00100 0.00200