monazite

A reddish-brown phosphate mineral containing rare-earth metals, (Ce, La, Nd, Y, Th)PO₄, important as a source of cerium and thorium.

A phosphate of the cerium metals, usually containing some thorium silicate.

A mineral occurring usually in small isolated crystals, — a phosphate of the cerium metals.

any of a range of reddish-brown minerals that are mixed phosphates of the lighter rare earth elements lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium and yttrium

a reddish-brown mineral containing rare earth metals; an important source of thorium and cerium