monazita

Monazite is a reddish-brown phosphate mineral that serves as a principal source of rare earth elements. It is a mineral group rather than a single compound, with varieties such as monazite-(Ce), monazite-(La), and monazite-(Nd) named for the dominant rare earth element. Its general formula is (REE)PO4, with variable thorium and uranium contents in many samples, which introduces radiological considerations for mining and processing.

Monazite occurs as an accessory mineral in igneous and metamorphic rocks and as grains in sedimentary placers. It commonly concentrates in heavy mineral sand deposits along coastlines, where weathering releases resistant minerals from continental crust and concentrates them with other heavy minerals such as zircon, rutile, and ilmenite.

It is mined for its rare earth content, typically by crushing and concentrating heavy minerals, then separating monazite from the ore by gravity, magnetic, and chemical methods. Because thorium and sometimes uranium occur in monazite, radiological safety and regulatory controls are important during extraction, processing, and waste disposal. Historically, monazite sands were used as a source of thorium for gas mantles and other applications; today REE extraction is the primary goal.

Monazite remains an important natural source of rare earths, though its processing is shaped by radiological considerations and regulatory frameworks. Global supply depends on coastal placer deposits and the capacity to extract and refine REEs from monazite-rich concentrates.