data_9002346 _chemical_name 'Serandite' loop_ _publ_author_name 'Jacobsen S D' 'Smyth J R' 'Swope R J' 'Sheldon R I' _journal_name_full "American Mineralogist" _journal_volume 85 _journal_year 2000 _journal_page_first 745 _journal_page_last 752 _publ_section_title ; Two proton positions in the very strong hydrogen bond of serandite, NaMn2[Si3O8(OH)] Sample: X-ray ; _chemical_formula_sum 'Na Mn1.933 Si3 H O9' _cell_length_a 7.7185 _cell_length_b 6.9064 _cell_length_c 6.7624 _cell_angle_alpha 90.492 _cell_angle_beta 94.085 _cell_angle_gamma 102.775 _cell_volume 350.557 _symmetry_space_group_name_H-M 'P -1' loop_ _symmetry_equiv_pos_as_xyz 'x,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_Uiso_or_equiv Na 0.55614 0.25385 0.35237 1.00000 ? Mn1 0.85219 0.59405 0.13637 0.94400 ? Mn2 0.84956 0.08396 0.13308 0.98900 ? Si1 0.21589 0.40239 0.34113 1.00000 ? Si2 0.20581 0.95249 0.35090 1.00000 ? Si3 0.45398 0.73904 0.14312 1.00000 ? H 0.17900 0.62100 0.53300 1.00000 0.06400 O1 0.66327 0.79612 0.11507 1.00000 ? O2 0.32289 0.70965 0.94371 1.00000 ? O3 0.18070 0.49542 0.55276 1.00000 ? O4 0.15867 0.84596 0.55620 1.00000 ? O5 0.06121 0.39059 0.16778 1.00000 ? O6 0.05273 0.89324 0.17232 1.00000 ? O7 0.40696 0.53359 0.27366 1.00000 ? O8 0.39617 0.90570 0.28860 1.00000 ? O9 0.26035 0.19025 0.39346 1.00000 ?