Tantalum is primarily obtained from the minerals columbite ((Fe, Mn, Mg)[(Nb, Ta).sub.2][O.sub.6]), tantalite ((Fe, Mn)[(Ta, Nb).sub.2][O.sub.6]) and euxenite
((Y, Ca, Er, La, Ce, U, Th)[(Nb, Ta, Ti).sub.2][O.sub.6]).
The NYF Mukinbudin pegmatite field has been known for rare minerals including allanite, euxenite
, fergusonite, ilmenorutile, monazite, xenotime and zircon since 2000.
Since the beginning of the 20th century it has been a fruitful collecting area, yielding fine crystals of euxenite
, gadolinite, allanite, aeschynite, fersmite and many other species from its rare-earth-enriched pegmatites.
Included were Madagascar rare-earth classics like sharp betafite crystals to 4 cm; well-composed earthy brown sprays of 2-cm euxenite
crystals; swarms of loose 1 and 2-cm cubes of lustrous black thorianite; and allanite crystal groups from Madagascar and from Alto Ligonha, Mozambique.
Other minerals reported include xenotime, euxenite
, bismutocolumbite, bismutomicrolite, microlite, hambergite, petali te, stilbite and apatite.
Associations include betafite, euxenite, monazite and xenotime-(Y) (DSGM, 1974).
Betafite has been reported from the Ile pegmatite, in association with euxenite, allanite and monazite, and from the Ehiale-Namovela-Massive-Horta group in association with euxenite and samarskite (DSGM, 1974).
Excellent albite, euxenite
, monazite and zircon crystals have been found there as well.