Olmsteadite Moore P B, Araki T, Kampf A R, Steele I M American Mineralogist 61 (1976) 5-11 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 0000485 7.512 10.000 6.492 90 90 90 Pb2_1m atom x y z occ Biso Nb .27254 .73837 0 .59 .44 Ta .27254 .73837 0 .41 .44 Fe .02061 0 .24183 .77 K .53021 .97416 .5 2.56 P1 .1832 .7412 .5 .61 P2 .3253 .4149 0 .55 O1 .0823 .8729 .5 .87 O2 .0631 .6192 .5 1.79 O3 .3059 .7376 .3090 1.23 O4 .4180 .5547 0 .87 O5 .4723 .3067 0 1.04 O6 .2138 .3978 .1976 .91 O7 .1575 .8999 0 1.16 O8 .0735 .6317 0 1.34 Wat .2524 .1117 .2720 2.52