β—钕褐钇铌矿(Fergusonite-beta-Nd)

至今,吐界上已经发现的褐钇铌矿族矿物中仅有钛褐钇铌矿、铈褐钇铌矿、铈-钇-褐钇铌矿……等,而未见有矿物中稀土元素以钕为最富的单斜钕褐钇铌矿的报道^1,4,5]。

β-FERGUSONITE (Nd)

Beta-Nd fergusonite was found in the ore of rare earth-niobium dolomite type of the Bayan Obo Group of Proterozoic age.The mineral is brown red to dark red in colour,streak pale brown,brittle,fracture conchoidal,with very week anisotropic.Electron microprobe analysis of the mineral gave Nb₂O₅ 41.00,Ta₂O₅ 0.11,ThO₂ 1.09,UO₂ 1.46,TiO₂ 0.17,MnO 0.30,FeO 0.27,CaO 0.29,ZrO,0.19,MgO 0.07,A1₂O₃ 0.12,SiO₂ 0.29,RE₂O,55.00 in percent,which led to the formula as follows:(Nd_0.58 Ce_0.27 La_0.04 Pr_0.08 Sm_0.08 Gd_0.02 Tb_0.02 Dy_0.02 Ho_0.01 Er_0.01 Tm_0.01Yb_0.01 Y_0.08)_1.02 (U.Th.Ca.Fe)_0.06]_0.08 Nb.Ta.Ti]_0.94O₄ or can be simplified as (Nd Ce)NbO₄ Rare earth distribution is La_3.78·Ce_25.71·Pr_7.65·Nd_39.36·Sm_8.44·Eu_0.39·Gd_2.57·Tb_1.33·Dy_1.84·Ho_1.06·Er_0.96·Tm_0.68·Yb_0.86·Lu_0.55·Y_4.82 in percent.XRD powder data indicate that the stronger lines are 3.2064(10),3.0253(10),2.7976(5),2.6961(5),2.0648(5),1.9549(5),1.8832(9),1.6691(5),1.6024(5).The minreal belongs to monoclinic system with a₀=5.07 Å_±;,b₀=5.62 Å_±; c₀=5.41_±, β=93.0_±. Infrered absorption spectra of β fergusonite (Nd) shows bands (1452,1094,1020,878,614,466).As Nd occurs in highest concentration among the rare earth elements it may be supposed that the mineral is the product of mineralized stage.