monazitok

Monazitok are the monazite group of phosphate minerals and a significant source of rare earth elements. They commonly occur as accessory minerals in igneous and metamorphic rocks, and are also found in heavy-mineral sands along coastlines. The minerals share a phosphate-based composition in which rare earth elements dominate, though exact content varies among samples.

Chemical composition and structure: Monazite minerals have the general formula (REE,RE’)PO4, with REE representing rare earth elements such as cerium, lanthanum, neodymium, praseodymium and samarium. Many samples contain thorium and, to a lesser extent, uranium. Monazite crystallizes in the monoclinic system and is typically yellow-brown to reddish-brown with a resinous luster. The hardness is about 5–5.5 on the Mohs scale, and the minerals are relatively dense.

Occurrence and deposits: Monazitok are found as accessory minerals in granitic and granitic-batholith rocks, as well as in other igneous and metamorphic rocks. They are particularly concentrated in placer deposits and heavy-mineral sands formed by erosion and sedimentation, including beach and dune sands. Commercial mining often targets these sands to recover rare earth elements.

Uses and processing: Monazite is a principal source of several light rare earth elements (such as cerium and lanthanum) and is sometimes associated with thorium. Processing involves mineral separation followed by chemical processing to extract individual REEs. The presence of thorium and uranium requires radiological controls and careful environmental management during mining, processing, and waste handling.

See also: Monazite, Rare earth element, Heavy mineral sand.