data_global _chemical_name_mineral 'Chevkinite-(Nd)' loop_ _publ_author_name 'Calvo C' 'Faggiani R' _journal_name_full 'American Mineralogist' _journal_volume 59 _journal_year 1974 _journal_page_first 1277 _journal_page_last 1285 _publ_section_title ; A re-investigation of the crystal structures of chevkinite and perrierite Coordinates to O8 revised by Dr. Zhuming Yang, December 2001 ; _database_code_amcsd 433 _chemical_compound_source 'natural, but location not given' _chemical_formula_sum 'Nd4 Si4 Mg1.999 Ti3.001 O22' _cell_length_a 13.328 _cell_length_b 5.727 _cell_length_c 10.971 _cell_angle_alpha 90.0 _cell_angle_beta 100.91 _cell_angle_gamma 90.0 _cell_volume 822.275 _exptl_crystal_density_diffrn 4.982 _symmetry_space_group_name_H-M 'P 1 21/a 1' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2-y,z' '1/2-x,1/2+y,-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 Nd1 0.35442 0.0226 0.23312 1.0 0.0095 Nd2 0.07127 -0.03662 0.24017 1.0 0.0094 Si1 0.2015 0.4972 0.2306 1.0 0.0069 Si2 0.3596 0.5019 0.047 1.0 0.0076 Mg 0.0 0.5 0.0 1.0 0.0078 Ti1 0.2434 0.2466 0.5 0.68 0.0082 Mg1 0.2434 0.2466 0.5 0.32 0.0082 Ti2a 0.0 0.5 0.5 0.807 0.0111 Mg2a 0.0 0.5 0.5 0.193 0.0111 Ti2b 0.5 0.5 0.5 0.834 0.0093 Mg2b 0.5 0.5 0.5 0.166 0.0093 O1 0.2393 -0.2098 0.3133 1.0 0.0075 O11 0.217 0.2527 0.313 1.0 0.0081 O2 -0.0247 -0.2527 0.3742 1.0 0.0085 O21 -0.0214 0.2448 0.3736 1.0 0.0093 O3 0.4131 -0.2493 0.0946 1.0 0.0093 O31 0.4437 0.2947 0.0931 1.0 0.0107 O4 0.1457 -0.0104 0.4757 1.0 0.0106 O5 0.1511 0.5044 0.5099 1.0 0.0105 O6 0.0866 0.5469 0.1686 1.0 0.0113 O7 0.2741 0.4477 0.1307 1.0 0.0151 O8 0.3132 0.4892 -0.0985 1.0 0.0074