data_global _chemical_name_mineral 'Alstonite' loop_ _publ_author_name 'Bindi L' 'Roberts A C' 'Biagioni C' _journal_name_full 'Mineralogical Magazine' _journal_volume 84 _journal_year 2020 _journal_page_first 699 _journal_page_last 704 _publ_section_title ; The crystal structure of alstonite, BaCa(CO3)2: an extraordinary example of 'hidden' complex twinning in large single crystals ; _database_code_amcsd 0020914 _chemical_compound_source 'Fallowfield mine, Northumberland, England' _chemical_formula_sum 'Ba Ca C2 O6' _cell_length_a 17.4360 _cell_length_b 17.4360 _cell_length_c 6.1295 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 120 _cell_volume 1613.799 _exptl_crystal_density_diffrn 3.672 _symmetry_space_group_name_H-M 'P 3 1 m' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x-y,-y,z' '-y,x-y,z' 'y,x,z' '-x+y,-x,z' '-x,-x+y,z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv Ba1 0.65993 0.00000 0.09659 0.01630 Ba2 0.83960 0.00000 0.59580 0.02955 Ba3 0.50180 0.15658 0.09689 0.01823 Ca1 0.16090 0.00000 0.09850 0.02210 Ca2 0.32472 0.00000 0.59710 0.02710 Ca3 0.31951 0.49915 0.59620 0.02690 C1 0.33280 0.16240 0.92780 0.02710 C2 0.33360 0.16360 0.43450 0.01930 C3 0.00000 0.00000 0.35200 0.01800 C4 0.00000 0.00000 0.83880 0.00700 C5 0.50150 0.00000 0.82870 0.01680 C6 0.33333 0.66667 0.44080 0.02800 C7 0.33333 0.66667 0.91900 0.03600 C8 0.50220 0.00000 0.35760 0.01700 O1 0.40950 0.23720 0.91940 0.03690 O2 0.32940 0.08390 0.92680 0.03120 O3 0.25470 0.16190 0.94250 0.03730 O4 0.33950 0.23820 0.44290 0.03730 O5 0.25890 0.09060 0.42560 0.03870 O6 0.40810 0.15970 0.44940 0.03400 O7 0.07080 0.00000 0.84710 0.02570 O8 0.07420 0.57800 0.83670 0.03550 O9 0.42870 0.00000 0.84240 0.03220 O10 0.67320 0.26040 0.91840 0.03970 O11 0.59810 0.25650 0.45450 0.04800 O12 0.57750 0.07270 0.35090 0.03000 O13 0.43110 0.00000 0.35040 0.03480 O14 0.07250 0.00000 0.35000 0.06700 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 Ba1 0.00819 0.01480 0.02810 0.00742 -0.00027 0.00000 Ba2 0.03230 0.01860 0.03320 0.00928 -0.00080 0.00000 Ba3 0.01122 0.01780 0.02705 0.00825 -0.00011 0.00030 Ca1 0.02740 0.00990 0.02330 0.00490 -0.00070 0.00000 Ca2 0.02950 0.01750 0.03020 0.00880 0.00080 0.00000 Ca3 0.03080 0.01650 0.03330 0.01170 0.00080 -0.00010 C1 0.02600 0.03600 0.01700 0.01400 -0.00580 -0.00400 C2 0.02400 0.02100 0.01500 0.01300 0.00320 0.00150 C3 0.00700 0.00700 0.04100 0.00360 0.00000 0.00000 C6 0.03400 0.03400 0.01500 0.01700 0.00000 0.00000 C7 0.04400 0.04400 0.01900 0.02200 0.00000 0.00000 C8 0.01000 0.00400 0.03500 0.00200 -0.00300 0.00000 O1 0.02700 0.05300 0.03100 0.02000 -0.00400 -0.00200 O2 0.03200 0.01600 0.04100 0.00900 0.00300 0.00160 O3 0.03000 0.03700 0.04200 0.01500 -0.00100 -0.00600 O4 0.01700 0.02800 0.05900 0.00500 0.00100 -0.00100 O5 0.02900 0.02400 0.05300 0.00500 0.00200 0.00200 O6 0.02400 0.03200 0.04700 0.01500 0.00000 0.00500 O7 0.02300 0.02200 0.03100 0.01100 -0.00100 0.00000 O8 0.03500 0.01400 0.05800 0.01200 0.01000 0.01100 O9 0.01800 0.02700 0.05500 0.01400 -0.00300 0.00000 O10 0.03600 0.05700 0.03500 0.03000 -0.00600 -0.00200 O11 0.04400 0.05900 0.05100 0.03300 0.00400 0.00300 O12 0.03100 0.04800 0.01630 0.02400 -0.00330 -0.00400 O13 0.04400 0.04400 0.01700 0.02200 0.00700 0.00000 O14 0.03300 0.09600 0.09200 0.04800 0.00100 0.00000