data_global _chemical_name_mineral 'Poldervaartite' loop_ _publ_author_name 'Yano T' 'Urabe K' 'Ikawa H' 'Teraushi T' 'Ishizawa N' 'Udagawa S' _journal_name_full 'Acta Crystallographica, Section C' _journal_volume 49 _journal_year 1993 _journal_page_first 1555 _journal_page_last 1559 _publ_section_title ; Structure of alpha-dicalcium silicate hydrate Note: Structure revised in Marsh (1994) ; _database_code_amcsd 0010286 _chemical_formula_sum 'Ca2 Si O5' _cell_length_a 9.487 _cell_length_b 9.179 _cell_length_c 10.666 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 928.808 _exptl_crystal_density_diffrn 2.692 _symmetry_space_group_name_H-M 'P 21 21 21' loop_ _space_group_symop_operation_xyz 'x,y,z' '-x,1/2+y,1/2-z' '1/2+x,1/2-y,-z' '1/2-x,-y,1/2+z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_U_iso_or_equiv Ca1 0.48080 0.17030 0.06600 ? Ca2 0.51200 0.83120 0.92860 ? Ca3 0.34710 0.00660 0.38860 ? Ca4 0.65630 0.99530 0.61070 ? Si1 0.16870 0.20950 0.16390 ? Si2 0.83060 0.78380 0.84400 ? O1 0.06190 0.13240 0.06560 0.00960 O2 0.94980 0.85630 0.93430 0.00390 O3 0.24320 0.34870 0.07350 0.01350 O4 0.74580 0.65720 0.92640 0.00770 O5 0.29810 0.10440 0.19500 0.01450 O6 0.70650 0.90410 0.81320 0.00670 O7 0.10990 0.29000 0.28120 0.00700 O8 0.90690 0.70600 0.72180 0.00780 O9 0.39460 0.44920 0.39120 0.01180 O10 0.60670 0.54580 0.60090 0.00620 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 Ca1 0.00570 0.00750 0.00660 -0.00280 -0.00270 0.00240 Ca2 0.01060 0.01110 0.00860 -0.00160 -0.00270 -0.00150 Ca3 0.00310 0.00180 0.00220 0.00190 0.00170 0.00290 Ca4 0.01330 0.01690 0.01690 -0.00350 -0.00400 -0.00460 Si1 0.00570 0.00690 0.00530 -0.00010 -0.00330 -0.00090 Si2 0.00780 0.00520 0.00530 -0.00060 0.00280 0.00260