data_global
_chemical_name_mineral 'Olmsteadite'
loop_
_publ_author_name
'Moore P B'
'Araki T'
'Kampf A R'
'Steele I M'
_journal_name_full 'American Mineralogist'
_journal_volume 61
_journal_year 1976
_journal_page_first 5
_journal_page_last 11
_publ_section_title
;
 Olmstaedite, K2Fe2[Fe2(Nb,Ta)2O4(H2O)4(PO4)4], a new species, its crystal
 structure and relation to vauxite and montgomeryite
;
_database_code_amcsd 485
_chemical_formula_sum '(Nb.59 Ta.41) Fe2 K P2 O12 H4'
_cell_length_a 7.512
_cell_length_b 10.0
_cell_length_c 6.492
_cell_angle_alpha 90.0
_cell_angle_beta 90.0
_cell_angle_gamma 90.0
_cell_volume 487.679
_exptl_crystal_density_diffrn  3.662
_symmetry_space_group_name_H-M 'P b 21 m'
loop_
_space_group_symop_operation_xyz
  'x,y,z'
  '-x,1/2+y,z'
  'x,y,-z'
  '-x,1/2+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
Nb   0.27254  0.73837  0.0  0.59  0.00557
Ta   0.27254  0.73837  0.0  0.41  0.00557
Fe   0.02061  0.0  0.24183  1.0  0.00975
K   0.53021  0.97416  0.5  1.0  0.03242
P1   0.1832  0.7412  0.5  1.0  0.00773
P2   0.3253  0.4149  0.0  1.0  0.00697
O1   0.0823  0.8729  0.5  1.0  0.01102
O2   0.0631  0.6192  0.5  1.0  0.02267
O3   0.3059  0.7376  0.309  1.0  0.01558
O4   0.418  0.5547  0.0  1.0  0.01102
O5   0.4723  0.3067  0.0  1.0  0.01317
O6   0.2138  0.3978  0.1976  1.0  0.01153
O7   0.1575  0.8999  0.0  1.0  0.01469
O8   0.0735  0.6317  0.0  1.0  0.01697
Wat   0.2524  0.1117  0.272  1.0  0.03192