data_global _chemical_name_mineral 'Pigeonite' loop_ _publ_author_name 'Camara F' 'Carpenter M A' 'Domeneghetti M C' 'Tazzoli V' _journal_name_full 'Physics and Chemistry of Minerals' _journal_volume 29 _journal_year 2002 _journal_page_first 331 _journal_page_last 340 _publ_section_title ; Non-convergent ordering and displacive phase transition in pigeonite: in situ HT XRD study Sample: hgd, T = 650 C ; _database_code_amcsd 0008638 _chemical_compound_source 'from rhyodacite, Parana, Brazil' _chemical_formula_sum 'Mg.461 Fe.419 Mn.014 Ca.106 Si O3' _cell_length_a 9.801 _cell_length_b 9.008 _cell_length_c 5.296 _cell_angle_alpha 90 _cell_angle_beta 109.01 _cell_angle_gamma 90 _cell_volume 442.070 _exptl_crystal_density_diffrn 3.477 _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 0.25020 0.65320 0.23970 0.75290 0.01800 FeM1 0.25020 0.65320 0.23970 0.22220 0.01800 MnM1 0.25020 0.65320 0.23970 0.00720 0.01800 CaM1 0.25020 0.65320 0.23970 0.01790 0.01800 MgM2 0.25280 0.01880 0.23820 0.16990 0.02900 FeM2 0.25280 0.01880 0.23820 0.61480 0.02900 MnM2 0.25280 0.01880 0.23820 0.02020 0.02900 CaM2 0.25280 0.01880 0.23820 0.19510 0.02900 SiA 0.04350 0.33980 0.27030 1.00000 0.01500 SiB 0.54700 0.83810 0.24800 1.00000 0.01400 O1A 0.86910 0.33810 0.16090 1.00000 0.01900 O1B 0.37250 0.83840 0.14180 1.00000 0.02000 O2A 0.12220 0.49680 0.33970 1.00000 0.02500 O2B 0.62620 0.99050 0.36320 1.00000 0.02900 O3A 0.10240 0.25160 0.55830 1.00000 0.03500 O3B 0.60310 0.72220 0.50450 1.00000 0.03100 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 0.01900 0.01900 0.01600 0.00000 0.00300 0.00000 FeM1 0.01900 0.01900 0.01600 0.00000 0.00300 0.00000 MnM1 0.01900 0.01900 0.01600 0.00000 0.00300 0.00000 CaM1 0.01900 0.01900 0.01600 0.00000 0.00300 0.00000 MgM2 0.02900 0.03400 0.02000 0.00300 0.00200 0.00200 FeM2 0.02900 0.03400 0.02000 0.00300 0.00200 0.00200 MnM2 0.02900 0.03400 0.02000 0.00300 0.00200 0.00200 CaM2 0.02900 0.03400 0.02000 0.00300 0.00200 0.00200 SiA 0.01400 0.01600 0.01600 -0.00100 0.00600 -0.00200 SiB 0.01300 0.01500 0.01600 -0.00200 0.00500 -0.00100 O1A 0.01400 0.02400 0.01900 0.00100 0.00500 0.00100 O1B 0.01400 0.02300 0.02100 0.00100 0.00400 -0.00100 O2A 0.03000 0.01700 0.03200 -0.00800 0.01400 -0.00300 O2B 0.03000 0.02600 0.03200 -0.01100 0.01400 -0.01000 O3A 0.01800 0.05200 0.03200 0.00300 0.00600 0.02300 O3B 0.02100 0.04300 0.02900 0.00400 0.00900 0.01900