fergusonite
noun
fer·gu·son·ite
ˈfərgəsəˌnīt
plural -s
: a brownish black mineral (Y,Er,Ce,Fe,)(Nb,Ta,Ti)O4 consisting essentially of an oxide of yttrium, erbium, niobium, and tantalum with other metals often including uranium and isomorphous with formanite (hardness 5.5–6)
Word History
Etymology
Robert Ferguson †1865 Scottish physician + English -ite