data_global _chemical_name_mineral 'Polyakovite-(Ce)' loop_ _publ_author_name 'Popov V A' 'Pautov L A' 'Sokolova E V' 'Hawthorne F C' 'McCammon C A' 'Bazhenova L F' _journal_name_full 'The Canadian Mineralogist' _journal_volume 39 _journal_year 2001 _journal_page_first 1095 _journal_page_last 1104 _publ_section_title ; Polyakovite-(Ce), (REE,Ca)4(Mg,Fe)(Cr,Fe)2(Ti,Nb)2Si4O22, a new metamict mineral species from the Ilmen Mountains, Southern Urals, Russia: Mineral discription and crystal chemistry ; _database_code_amcsd 0005725 _chemical_compound_source 'Ilmen Mountains, Southern Urals, Russia' _chemical_formula_sum '(Ce1.84 La1.24 Nd.36 Pr.16 Y.04 Ca.24 Th.12) Mg.8 Fe.92 Ti1.52 Nb.32 Cr1.28 Si4 O22' _cell_length_a 13.398 _cell_length_b 5.6974 _cell_length_c 11.042 _cell_angle_alpha 90 _cell_angle_beta 100.539 _cell_angle_gamma 90 _cell_volume 828.659 _exptl_crystal_density_diffrn 5.009 _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 CeA1 0.35606 0.00000 0.73540 0.46000 0.01520 LaA1 0.35606 0.00000 0.73540 0.31000 0.01520 NdA1 0.35606 0.00000 0.73540 0.09000 0.01520 PrA1 0.35606 0.00000 0.73540 0.04000 0.01520 YA1 0.35606 0.00000 0.73540 0.01000 0.01520 CaA1 0.35606 0.00000 0.73540 0.06000 0.01520 ThA1 0.35606 0.00000 0.73540 0.03000 0.01520 CeA2 0.07041 0.00000 0.74116 0.46000 0.01990 LaA2 0.07041 0.00000 0.74116 0.31000 0.01990 NdA2 0.07041 0.00000 0.74116 0.09000 0.01990 PrA2 0.07041 0.00000 0.74116 0.04000 0.01990 YA1 0.07041 0.00000 0.74116 0.01000 0.01990 CaA2 0.07041 0.00000 0.74116 0.06000 0.01990 ThA2 0.07041 0.00000 0.74116 0.03000 0.01990 Mg1 0.50000 0.00000 0.50000 0.80000 0.01690 Fe1 0.50000 0.00000 0.50000 0.20000 0.01690 Ti2 0.25000 0.25000 0.00000 0.76000 0.00930 Nb2 0.25000 0.25000 0.00000 0.16000 0.00930 Cr3 0.00000 0.00000 0.00000 0.64000 0.01200 Fe3 0.00000 0.00000 0.00000 0.36000 0.01200 Cr4 0.50000 0.00000 0.00000 0.64000 0.01330 Fe4 0.50000 0.00000 0.00000 0.36000 0.01330 Si(1) 0.20220 -0.50000 0.73270 1.00000 0.01050 Si(2) 0.35820 -0.50000 0.54520 1.00000 0.01230 O(1) 0.47850 0.25200 0.87260 1.00000 0.01080 O(2) 0.14720 0.00000 0.97820 1.00000 0.01090 O(3) 0.18880 0.00000 0.59820 1.00000 0.01460 O(4) 0.34950 0.00000 0.98870 1.00000 0.00900 O(5) 0.42830 0.26890 0.59150 1.00000 0.02540 O(6) 0.22790 -0.73600 0.81470 1.00000 0.01320 O(7) 0.08690 -0.50000 0.66900 1.00000 0.03020 O(8) 0.27500 -0.50000 0.63200 1.00000 0.03540 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 CeA1 0.01220 0.01940 0.01390 0.00000 0.00200 0.00000 LaA1 0.01220 0.01940 0.01390 0.00000 0.00200 0.00000 NdA1 0.01220 0.01940 0.01390 0.00000 0.00200 0.00000 PrA1 0.01220 0.01940 0.01390 0.00000 0.00200 0.00000 YA1 0.01220 0.01940 0.01390 0.00000 0.00200 0.00000 CaA1 0.01220 0.01940 0.01390 0.00000 0.00200 0.00000 ThA1 0.01220 0.01940 0.01390 0.00000 0.00200 0.00000 CeA2 0.01220 0.03380 0.01360 0.00000 0.00180 0.00000 LaA2 0.01220 0.03380 0.01360 0.00000 0.00180 0.00000 NdA2 0.01220 0.03380 0.01360 0.00000 0.00180 0.00000 PrA2 0.01220 0.03380 0.01360 0.00000 0.00180 0.00000 YA1 0.01220 0.03380 0.01360 0.00000 0.00180 0.00000 CaA2 0.01220 0.03380 0.01360 0.00000 0.00180 0.00000 ThA2 0.01220 0.03380 0.01360 0.00000 0.00180 0.00000 Mg1 0.02000 0.01430 0.01610 0.00000 0.00220 0.00000 Fe1 0.02000 0.01430 0.01610 0.00000 0.00220 0.00000 Ti2 0.01130 0.01010 0.00610 0.00020 0.00030 0.00020 Nb2 0.01130 0.01010 0.00610 0.00020 0.00030 0.00020 Cr3 0.01350 0.01560 0.00670 0.00000 0.00170 0.00000 Fe3 0.01350 0.01560 0.00670 0.00000 0.00170 0.00000 Cr4 0.01500 0.01690 0.00710 0.00000 -0.00030 0.00000 Fe4 0.01500 0.01690 0.00710 0.00000 -0.00030 0.00000 Si(1) 0.01800 0.00760 0.00540 0.00000 0.00090 0.00000 Si(2) 0.01280 0.01350 0.01030 0.00000 0.00170 0.00000 O(1) 0.01140 0.01070 0.00970 -0.00050 0.00040 0.00050 O(2) 0.01380 0.00900 0.01070 0.00000 0.00420 0.00000 O(3) 0.01930 0.01890 0.00460 0.00000 -0.00040 0.00000 O(4) 0.00760 0.00840 0.00940 0.00000 -0.00260 0.00000 O(5) 0.03400 0.02470 0.01590 0.01200 0.00030 0.00210 O(6) 0.02200 0.01090 0.00600 0.00280 0.00100 -0.00030 O(7) 0.02010 0.05760 0.01170 0.00000 -0.00050 0.00000 O(8) 0.03450 0.06190 0.01510 0.00000 0.01850 0.00000