small piece of monazite, REE, mineralogy
Monazite is one of the most common REE mineral of economic value
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Mineralogy

There is a wealth of different REE bearing minerals. REE are found in almost all mineral groups including silicates (e.g. eudialyte, allanite, zircon, steenstrupine etc.), fluoro-carbonates (e.g. bastnaesite, synchisite, parisite, fluocerite), oxides (e.g. euxenite, fergusonite, pyrochlore, loparite, cheralite) and phosphates (e.g. xenotime, churchite, florencite, britholite, apatite).

Today,  generally three mineral species, i.e. bastnaesite, a LREE fluorocarbonate (China and USA); monazite, a LREE/HREE phosphate (Australia) and xenotime, a HREE yttrium phosphate (Malyasia) as well as lateritic ore containing HREE rich ion adsorption clays in China are exploited commercially. Besides, loparite is processed in Russia to extract REE enriched in the Lovozero Complex.

Due to similar physical and chemical properties the different rare earth elements (REE) occur together and are recovered from their mineral host as a mixture of different REE. Subsequent sequential chemical processing to separate and concentrate individual REE to high levels of purity involves additional cost. In most deposits, the balance is tipped towards the light rare earth elements (LREE) which comprise 97-99% of resources. In contrast, deposits having an unusual balance with a high proportion of heavy rare earth elements (HREE) are very rare. Many of the HREE play a crucial role in emerging green energy and high tech applications together with the fast growing demand in the lighting industries (LED), however, rendering HREE much more valuable than LREE.

Bastnaesite deposits in China and the USA constitute the largest percentage of the world’s rare earth reserves, while monazite deposits in Australia, Brazil, China, India, Malaysia, South Africa, Sri Lanka, Thailand, and the United States constitute the second largest segment.