data_global _chemical_name_mineral 'Sphaerobertrandite' loop_ _publ_author_name 'Pekov I V' 'Chukanov N V' 'Larsen A O' 'Merlino S' 'Pasero M' 'Pushcharovsky D Y' 'Ivaldi G' 'Zadov A E' 'Grishin V G' 'Asheim A' 'Tafto J' 'Chistyakova N I' _journal_name_full 'European Journal of Mineralogy' _journal_volume 15 _journal_year 2003 _journal_page_first 157 _journal_page_last 166 _publ_section_title ; Sphaerobertrandite, Be3SiO4(OH)2: new data, crystal structure and genesis ; _database_code_amcsd 0006960 _chemical_formula_sum 'Be3 Si O6 H2' _cell_length_a 5.082 _cell_length_b 4.640 _cell_length_c 17.696 _cell_angle_alpha 90 _cell_angle_beta 106.13 _cell_angle_gamma 90 _cell_volume 400.853 _exptl_crystal_density_diffrn 2.537 _symmetry_space_group_name_H-M 'P 1 21/c 1' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,1/2-y,1/2+z' '-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 Be1 0.29000 0.41600 0.11980 0.00600 Be2 0.62900 0.08900 0.96040 0.00700 Be3 0.11000 0.91700 0.29240 0.00600 Si 0.02740 0.41950 0.37550 0.00730 O1 0.02300 0.57400 0.14300 0.00800 O2 0.04500 0.57100 0.29330 0.00800 O3 0.22800 0.06900 0.09900 0.00100 O4 0.69700 0.97400 0.05400 0.00800 O-H5 0.30700 0.57500 0.04130 0.01100 O-H6 0.55700 0.46500 0.19390 0.01300