xenotime

noun

xen·o·time

ˈzenəˌtīm

plural -s

: a mineral YPO₄ that is a phosphate of yttrium occurring in usually brown or yellow tetragonal crystals and rolled grains and that often also contains thorium, erbium, cerium, or other elements (hardness 4–5, specific gravity 4.45–4.56)

Word History

Etymology

French xénotime, irregular (influence of xén- xen-) from Greek kenos empty, vain + timē honor; from the fact that it was wrongly thought at first to contain a new metal