(2) Monazite is a reddish brown phosphate mineral containing rare earth metals. It occurs usually in small isolated crystals. Due to the alpha decay of thorium and uranium, monazite contains a significant amount of helium, which can be extracted by heating. Monazite is an important ore for thorium,lanthanum, and cerium. It is often found in placer deposits. India, Madagascar, and South Africa have large deposits of monazite sands.