Identification: Monazite (Ce,La,Nd,Th)PO4, is a complex yellow to reddish-brown natural phosphate of the rare earth elements, mainly the cerium and lanthanum metals with some thorium. Yttrium, calcium, iron, and silica may be present. Specimens are translucent to opaque, but small crystals can be transparent. Hardness is 5 - 5.5, and specific gravity is approximately 4.6 - 5.7.

Occurrence: Occurs as grains in beach and Trail Ridge heavy mineral sands. Use: Monazite is an important source of cerium, thorium, and other rare-earth metals and compounds.