yttrotantalite

[ih-troh-tan-tl-ahyt]

noun

a mineral, tantalite and niobate of yttrium and various elements, as iron, and cerium, occurring in the form of brown-black crystals.

Origin of yttrotantalite

1800–10; yttro- (combining form of yttrium) + tantalite

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

It is also called Tantalium from the mineral tantalite and yttrotantalite, found in Sweden.
A Dictionary of Arts, Manufactures and Mines
Andrew Ure