data_global _chemical_name_mineral 'Cummingtonite' loop_ _publ_author_name 'Yang H' 'Hirschmann M M' _journal_name_full 'American Mineralogist' _journal_volume 80 _journal_year 1995 _journal_page_first 916 _journal_page_last 922 _publ_section_title ; Crystal structure of P2_1/m ferromagnesian amphibole and the role of cation ordering and composition in the P2_1/m - C2/m transition in cummingtonite Sample: UH1, untreated ; _database_code_amcsd 0001752 _chemical_formula_sum 'Fe2.558 Mg4.344 Al.012 Ca.086 Si8 O24' _cell_length_a 9.5015 _cell_length_b 18.1289 _cell_length_c 5.3089 _cell_angle_alpha 90 _cell_angle_beta 102.090 _cell_angle_gamma 90 _cell_volume 894.184 _exptl_crystal_density_diffrn 3.197 _symmetry_space_group_name_H-M 'C 1 2/m 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,z' '1/2+x,1/2-y,z' '-x,y,-z' '1/2-x,1/2+y,-z' '-x,-y,-z' '1/2-x,1/2-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 Fe1 0.00000 0.08690 0.50000 0.20000 0.00850 Mg1 0.00000 0.08690 0.50000 0.80000 0.00850 Fe2 0.00000 0.17710 0.00000 0.09100 0.00878 Mg2 0.00000 0.17710 0.00000 0.90300 0.00878 Al2 0.00000 0.17710 0.00000 0.00600 0.00878 Fe3 0.00000 0.00000 0.00000 0.16400 0.00660 Mg3 0.00000 0.00000 0.00000 0.83600 0.00660 Fe4 0.00000 0.25890 0.50000 0.90600 0.01179 Mg4 0.00000 0.25890 0.50000 0.05100 0.01179 Ca4 0.00000 0.25890 0.50000 0.04300 0.01179 Si1 0.28790 0.08420 0.27450 1.00000 0.00711 Si2 0.29790 0.16880 0.78120 1.00000 0.00724 O1 0.11420 0.08690 0.20920 1.00000 0.00862 O2 0.12320 0.17210 0.71930 1.00000 0.00914 O3 0.11330 0.00000 0.70680 1.00000 0.01071 O4 0.38050 0.24540 0.76890 1.00000 0.01161 O5 0.35140 0.13130 0.06460 1.00000 0.01312 O6 0.34990 0.11850 0.55860 1.00000 0.01491 O7 0.34340 0.00000 0.26990 1.00000 0.01299