BOX D-1

Lanthanide Series of Rare Earth Elements

Lanthanum (La)

Cerium (Ce)

Praseodymium (Pr)

Neodymium (Nd)

Promethium (Pm)

Samarium (Sm)

Europium (Eu)

Gadolinium (Gd)

Terbium (Tb)

Dysprosium (Dy)

Holmium (Ho)

Erbium (Er)

Thulium (Tm)

Ytterbium (Yb)

Lutetium (Lu)

magnets (2 percent); and other uses (13 percent) (USGS, 2007). The little recycling that is done is mostly carried out on permanent magnet scrap. In the aggregate between 2002 and 2005 the countries that supplied REEs to the world market, along with the share of the demand they satisfied, are as follows: China (76 percent); France (9 percent); Japan (4 percent); Russia (3 percent); and other (8 percent). In 2006 imports to and exports from the United States increased over 2005, and this trend may be expected to continue in the future.

Rare earth compounds are used in automotive catalytic converters and other applications. For instance, cerium compounds are used mainly for automotive catalytic converters, glass polishing, and glass additives. Yttrium compounds are used in fiber optics, lasers, oxygen sensors, phosphors for fluorescent lighting, color televisions, electronic thermometers, x-ray intensifying screens, pigments, super-conductors, and other items. Mixed rare earth compounds and rare earth metals and their alloys are used in permanent magnets, base-metal alloys, superalloys, pyrophoric alloys, lighter flints, and armaments; the amounts used have increased lately. The use of rare earth chlorides for fluid cracking catalysts in oil refining has declined.

Molycorp has shut down mining at the Mountain Pass location because of wastewater disposal problems but was expected, at the time of writing, to restart processing stockpiled ore late in 2007. Mining may not start for a couple of years (Thorne, 2007, personal communication).

REEs do not need to be as concentrated as most minerals for economic mining. The best source minerals for them are bastnasite and monazite. The largest deposits of bastnasite are those at Baiyun Obo (Inner Mongolia, China) and Mountain Pass, California, with the later already having been mentioned. Monazite deposits occur in Australia, Brazil, China, India, Malaysia, South Africa, Sri Lanka, Thailand, and the United States. Other minerals containing rare earths include apatite, cheralite, eudialyte, secondary monazite, loparite, phosphorites, rare-earth-bearing (ion adsorption) clays, spent uranium solutions, and xenotime. It has been speculated



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement