Monazite - Mining History

Mining History

Monazite sand from Brazil was first noticed in sand carried in ship's ballast by Carl Auer von Welsbach in the 1880s. Von Welsbach was looking for a way to obtain thorium for his newly invented incandescent mantles. Monazite sand was quickly adopted as the source of thorium for the mantles and was the foundation of what became the rare earth industry. Monazite sand was also briefly mined in North Carolina, but, shortly thereafter, deposits in southern India were found. Brazilian and Indian monazite dominated the industry before WWII, after which major mining activity transferred to South Africa and Bolivia. There are also large deposits in Australia.

Monazite was the only significant source of commercial lanthanides until bastnäsite began to be processed in about 1965. With declining interest in thorium as a potential nuclear fuel in the 1960s and increased concern over the disposal of the radioactive daughter products of thorium, bastnäsite came to displace monazite in the production of lanthanides due to its much lower thorium content. Any future increase in interest in thorium for atomic energy will bring monazite back into commercial use.