data_global _chemical_name_mineral 'Melanotekite' loop_ _publ_author_name 'Dorsam G' 'Liebscher A' 'Wunder B' 'Franz G' _journal_name_full 'American Mineralogist' _journal_volume 93 _journal_year 2008 _journal_page_first 573 _journal_page_last 583 _publ_section_title ; Crystal structures of synthetic melanotekite (Pb2Fe2Si2O9), kentrolite (Pb2Mn2Si2O9), and the aluminum analogue (Pb2Al2Si2O9) ; _database_code_amcsd 0004535 _chemical_compound_source 'Synthetic' _chemical_formula_sum 'Pb2 Fe2 Si2 O9' _cell_length_a 6.9788 _cell_length_b 11.0164 _cell_length_c 10.0881 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 775.586 _exptl_crystal_density_diffrn 6.220 _symmetry_space_group_name_H-M 'P b c n' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,-y,1/2+z' '-x,y,1/2-z' '1/2-x,1/2+y,z' '1/2+x,1/2-y,-z' '1/2+x,1/2+y,1/2-z' '1/2-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 Pb1 0.44820 0.30160 0.54940 0.70000 0.01040 Pb2 0.51210 0.30880 0.54990 0.30000 0.03000 Fe1 0.50000 0.00000 0.00000 1.00000 0.00700 Fe2 0.50000 0.15210 0.25000 1.00000 0.00730 Si 0.21510 -0.08640 0.25030 1.00000 0.00620 O1 0.34140 0.01090 0.33470 1.00000 0.00730 O2 0.30390 -0.10830 0.10190 1.00000 0.01280 O3 0.19150 -0.22010 0.32270 1.00000 0.01210 O4 0.00000 -0.02440 0.25000 1.00000 0.01990 O5 0.61460 0.14810 0.42590 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 Pb1 0.00790 0.01140 0.01200 -0.00180 -0.00110 -0.00120 Pb2 0.06520 0.01400 0.01080 0.00200 -0.00030 0.01400 Fe1 0.00910 0.00520 0.00690 -0.00050 -0.00120 0.00100 Fe2 0.00800 0.00810 0.00590 0.00000 0.00060 0.00000 Si 0.00330 0.00720 0.00810 0.00320 -0.00170 -0.00120 O1 0.01040 0.00430 0.00730 0.00400 -0.00090 -0.00140 O2 0.01580 0.01310 0.00960 -0.00180 0.00530 -0.00320 O3 0.00850 0.01590 0.01180 -0.00120 0.00090 -0.00380 O4 0.00500 0.01460 0.04000 0.00000 -0.00500 0.00000 O5 0.01110 0.01480 0.00830 0.00270 0.00050 -0.00490