Formula: YNbO4
Multiple oxide containing the rare earth elements niobium Nb and yttrium Y, usually metamict, tetragonal paramorph of clinofergusonite-(Y), which is monoclinic, fergusonite group
Specific gravity: 4.2 to 5.7
Hardness: 5½ to 6½
Streak: brown, yellow-brown, greenish grey
Colour: black to brownish grey, grey, yellow, brown
Common impurities: U,Th

Placer deposits

Fergusonite-(Y) is a typical mineral of rare-earth-bearing granite pegmatites, and it also occurs in placers. Associated minerals include monazite, gadolinite, thalénite-(Y), euxenite, allanite, zircon, biotite and magnetite (HOM).


At the J.G. Gole Quarry, Murchison Township, Nipissing District, Ontario, Canada, fergusonite-(Y) occurs with euxenite (Dana).

The type locality for fergusonite-(Y) is Kangeq, Sermersoq Island, Kujalleq, Greenland, Denmark.

At Iveland, Agder, Norway, fergusonite-(Y) occurs in pegmatites with gadolinite and thalénite-(Y) (Dana).

At Hundholmen, Narvik, Nordland, Norway, fergusonite-(Y) occurs allanite, yttrofluorite, xenotime and gadolinite (Dana).

At Buer, Bjørkedalen, Porsgrunn, Vestfold og Telemark, Norway, fergusonite-(Y) has been found in sparse amounts on the dump from a water tunnel. Gadolinite-(Ce) was discovered in the same dump, although not from the same pegmatite. The fergusonite-(Y) occurs as millimetre-sized tabular crystals in small vugs together with bavenite and helvine, and is obviously a late-crystallised mineral (JWW p156).

At the Blum mine, Ilmenskie mountains, Russia, fergusonite-(Y) occurs with samarskite and ilmenorutile (Dana).

At Ytterby, Resarö, Vaxholm, Stockholm County, Sweden, fergusonite-(Y) occurs in a pegmatite with xenotime, cyrtolite and biotite (Dana).

At Spruce Pine, Mitchell county, North Carolina, USA, fergusonite-(Y) occurs in pegmatites with allanite (Dana).

At Barringer Hill, Llano county, Texas, USA, fergusonite-(Y) occurs with gadolinite and other rare earth minerals (Dana).

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