Monazite and Bastnaesite in Many Places

The important raw material for cerium, monazite, is also the most important mineral source for thorium. As this metal was desirable it initially supported and accelerated the extraction of rare earth elements from monazite. TTie radioactivity of thorium has, however, created environmental problems for monazite. Nowadays, minerals free from radioactive components are favored for the extraction of REMs. 

The exploitable monazite resources are as a rule alluvial l and occur mainly as monazite sand. Seashore deposits atTravancore in India contain very large quantities of monazite. Other important sources are located on the Atlantic coast in Bahia, Brazil. In Austraha, monazite is obtained as a by-product when seashore sand is treated for extraction of ihnenite. Even yttrium group metals are extracted from monazite, in spite of the low original content. At Mountain Pass in Cahfomia large deposits of bastnaesite have been found. Euxenite is worked in Idaho for extraction of niobium and tantalum. Then REMs are obtained as by-products. 

China has the largest supply in the world of REMs. The recoverable resources account for near 75% of the world s total reserves. The description in this section is based on W. Minggin and D.Xuehong in ref. [17.9] and L. F. Trueb in ref. [17.13]. 

At Baiyunebo in Inner Mongoha, 135 km from Baotou, RE minerals are found together with minerals of iron, titanium and niobium. The deposit is worked for iron, which keeps the costs low for production of the RE metals. Both monazite and bastnaesite are mined and, because of that, the mine is very important as a source of the cerium group metals. The bastnaesite has a higher content of samarium and europium than the CaHfornian ore in Mountain Pass. As the monazite is low in thorium and free from uranium its radioactivity is low, which is a benefit for ore handhng. 

Mineral veins rich in bastnaesite have been found in mines in Weishan (Shandung) and in Mianning (Sichuan). These deposits give ores from which the rare earths are much easier to separate than from the Baiyunebo mixed minerals, favoring high yield 

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