data_global _chemical_name_mineral 'Fersmite' loop_ _publ_author_name 'Cummings J P' 'Simonsen S H' _journal_name_full 'American Mineralogist' _journal_volume 55 _journal_year 1970 _journal_page_first 90 _journal_page_last 97 _publ_section_title ; The crystal structure of calcium niobate (CaNb2O6) ; _database_code_amcsd 0000196 _chemical_compound_source 'Synthetic' _chemical_formula_sum 'Ca Nb2 O6' _cell_length_a 14.926 _cell_length_b 5.752 _cell_length_c 5.204 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 446.786 _exptl_crystal_density_diffrn 4.785 _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_U_iso_or_equiv Ca 0.00000 0.22440 0.75000 ? Nb 0.16530 0.31660 0.29870 ? O1 0.08930 0.09970 0.40400 0.01898 O2 0.10030 0.42800 0.00560 0.02334 O3 0.25760 0.13510 0.12660 0.00587 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 Ca 0.00542 0.00394 0.00388 0.00000 -0.00134 0.00000 Nb 0.00023 0.00164 0.00455 0.00017 0.00043 0.00045