data_global _chemical_name_mineral 'Sewardite' loop_ _publ_author_name 'Roberts A C' 'Cooper M A' 'Hawthorne F C' 'Criddle A J' 'Stirling J A R' _journal_name_full 'The Canadian Mineralogist' _journal_volume 40 _journal_year 2002 _journal_page_first 1191 _journal_page_last 1198 _publ_section_title ; Sewardite, CaFe2(AsO4)2(OH)2, the Ca-analogue of carminite, from Tsumeb, Namibia: Description and crystal structure ; _database_code_amcsd 0005788 _chemical_compound_source 'Tsumeb, Namibia' _chemical_formula_sum 'Ca Fe2 As2 O10 H2' _cell_length_a 16.461 _cell_length_b 7.434 _cell_length_c 12.131 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 1484.484 _exptl_crystal_density_diffrn 4.149 _symmetry_space_group_name_H-M 'C c c m' loop_ _space_group_symop_operation_xyz 'x,y,z' '1/2+x,1/2+y,z' 'x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' '-x,y,1/2-z' '1/2-x,1/2+y,1/2-z' '-x,y,1/2+z' '1/2-x,1/2+y,1/2+z' 'x,-y,1/2-z' '1/2+x,1/2-y,1/2-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_U_iso_or_equiv Ca1 0.00000 0.00000 0.25000 0.01850 Ca2 0.25000 0.75000 0.00000 0.01010 Fe 0.37896 0.13210 0.13404 0.00560 As1 0.04504 0.74470 0.00000 0.00540 As2 0.21374 0.00000 0.25000 0.00480 O1 0.01440 0.22460 0.11190 0.00500 O2 0.08850 0.52900 0.00000 0.00600 O3 0.12190 -0.11400 0.00000 0.01200 O4 0.15110 0.17770 0.23890 0.01100 O5 0.27200 -0.01500 0.13780 0.00500 O-H6 0.17110 0.23300 0.00000 0.00500 O-H7 0.42430 0.00000 0.25000 0.01700