Tantite
Natural tantalum pentoxide — transparent microscopic triclinic crystals with adamantine luster.
Intro adapted from Wikipedia (CC BY-SA).
Tantite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Ta₂O₅.
It crystallizes in the monoclinic crystal system (space group I2).
Key properties: Mohs hardness 7; specific gravity 8.45; Adamantine luster; optically biaxial.
IMA symbol Tan, IMA status: approved, named in 1982.
Found in a granite pegmatite cutting amphibolites (Mt. Vasin-Myl’k, Russia); in a highly fractionated pegmatite (Animikie Red Ace pegmatite, Wisconsin, USA).
It is found associated with Microlite, stibiotantalite, holtite (Mt. Vasin-Myl’k, Russia); manganotantalite, wodginite, tantalian manganotantalite, elbaite (Animikie Red Ace pegmatite.
The name refers to TANTalum in the composition.