Crystals of the very rare yttrium tantalate mineral formanite-(Y) from the TL in Australia (Cooglegong Pegmatite, Shaw River, East Pilbara Shire, Western Australia, Australia). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Formanite-(Y)
Formanite-(Y) is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula YTaO₄.
It crystallizes in the monoclinic crystal system (space group P2/a).
Key properties: Mohs hardness 5.5–6.5; specific gravity 6.17–6.24; Pale yellow streak; Metallic, resinous to greasy; weathered surfaces are dull luster; optically biaxial.
IMA symbol Frm-Y, IMA status: approved, named in 1944.
Found in granites and albitized, RE-rich pegmatitic veins; a detrital mineral in placers.
It is found associated with Cassiterite, monazite, euxenite, gadolinite (Cooglegong, Western Australia); plumbomicrolite, galena, native bismuth, löllingite (Mt. Ploskaya, Russia).
The mineral was named to honor Francis Gloster Forman (1904-1980), government geologist of Western Australia.