data_global _chemical_name_mineral 'Pigeonite' loop_ _publ_author_name 'Nestola F' 'Tribaudino M' 'Ballaran T B' _journal_name_full 'American Mineralogist' _journal_volume 89 _journal_year 2004 _journal_page_first 189 _journal_page_last 196 _publ_section_title ; High pressure behavior, transformation and crystal structure of synthetic iron-free pigeonite Sample: P = 2.6 GPa ; _database_code_amcsd 0003198 _chemical_formula_sum 'Mg1.85 Ca.15 Si2 O6' _cell_length_a 9.546 _cell_length_b 8.732 _cell_length_c 5.149 _cell_angle_alpha 90 _cell_angle_beta 108.12 _cell_angle_gamma 90 _cell_volume 407.913 _exptl_crystal_density_diffrn 3.308 _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 MgM2 0.25620 0.01960 0.22020 0.85000 0.01393 CaM2 0.25620 0.01960 0.22020 0.15000 0.01393 MgM1 0.25040 0.65520 0.22160 1.00000 0.00950 SiTA 0.04220 0.34150 0.28620 1.00000 0.00836 SiTB 0.55200 0.83870 0.22810 1.00000 0.00912 O1A 0.86560 0.33940 0.18200 1.00000 0.01001 O2A 0.12060 0.50340 0.31900 1.00000 0.00887 O3A 0.10540 0.27480 0.60000 1.00000 0.01267 O1B 0.37350 0.83830 0.12650 1.00000 0.01013 O2B 0.62930 0.98610 0.38200 1.00000 0.01646 O3B 0.60620 0.69860 0.45800 1.00000 0.01140 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 MgM2 0.01170 0.01920 0.01100 0.00620 0.00530 0.00400 CaM2 0.01170 0.01920 0.01100 0.00620 0.00530 0.00400