Original paper

Bastnäsite-(Nd), a new Nd-dominant member of the bastnäsite group from the Stetind pegmatite, Tysfjord, Nordland, Norway

Miyawaki, Ritsuro; Yokoyama, Kazumi; Husdal, Tomas A.


Bastnäsite-(Nd), ideally (Nd,La,Ce)(CO3)F, occurs in the Stetind pegmatite, Tysfjord, Nordland, Norway, in association with bastnäsite-(Ce), calcioancylite-(Nd) and/or kozoite-(Nd), stetindite, vyuntspakhkite-(Y) and Y-bearing fluorite. It forms 20 μm wide zones in outer parts of tabular bastnäsite-(Ce) crystals. Bastnäsite-(Nd) is translucent and is pale purplish pink to colourless with a vitreous, greasy or pearly lustre. Bastnäsite-(Nd) has a Mohs hardness of 4-4½, is brittle, and shows an indistinct cleavage on {1010} and an uneven fracture. The calculated density and mean refractive index are 5.23 g cm−3 and 1.76, respectively. It is hexagonal, space group P62c, a = 7.0792(13), c = 9.721(2) Å, V = 421.92(18) Å3 and Z = 6. The five strongest lines in the powder XRD pattern are [d(Å), I/I0, hkl]: 4.86, 71, 002; 3.54, 70, 110; 2.86, 100, 112; 2.04, 31, 300 and 2.00, 48, 114. The electron-microprobe analyses lead to the empirical formula (on the basis of M = C = 1 apfu): Nd0.353La0.253Ce0.251Pr0.086Sm0.037Gd0.016Y0.004Dy0.001CO2.978F1.044. Bastnäsite-(Nd) is a member of the bastnäsite group, and is the Nd-dominant analogue of bastnäsite-(Ce), bastnäsite-(La) and bastnäsite-(Y). Bastnäsite-(Nd) formed as a late phase in cavities in Y-bearing fluorite, which in turn is a late formation of the pegmatite.


bastnasitenew mineralneodymium carbonate fluoriderare-earth elementsstetind (norway)