What are the best answers for “a tantalate of uranium, yttrium, and calcium, of a brown or black color.”?

yttrocolumbite, yttrotantalite.

How many letters does the top answer for “a tantalate of uranium, yttrium, and calcium, of a brown or black color.” have?

The most common answer is yttrocolumbite (14 letters).

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

yttrocolumbite 14 letters web-def

A tantalate of uranium, yttrium, and calcium, of a brown or black color.

yttrotantalite 14 letters web-def

A tantalate of uranium, yttrium, and calcium, of a brown or black color.