monazite

noun

1. a reddish- or yellowish-brown mineral, a phosphate of cerium and lanthanum, (Ce,La)PO4: the principal ore of thorium.

noun

1. a yellow to reddish-brown mineral consisting of a phosphate of thorium, cerium, and lanthanum in monoclinic crystalline form

1. A yellow or reddish-brown monoclinic mineral that is a principal ore of several lanthanide (rare-earth) elements. It occurs as tabular crystals in pegmatites, granites, and metamorphic rocks, as well as in sand. Chemical formula: (Ce, La, Nd, Th)PO4.