Rare Earths are commonly separated into ‘light rare earths’ lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd) which are relatively abundant, and ‘heavy rare earths’ terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu) which are less abundant and more valuable.
The most common minerals that are processed to recover rare earths are listed in the table above. Hard rock deposits of Bastnasite and placer deposits of Monazite host most of the worlds economic concentrations of light rare earths and production is dominated by the Bayun Obo mine in Inner Mongolia where it is a by-product of iron ore mining. The more valuable heavy rare earths are mainly sourced from ionic absorption clays and xenotime in southern China.
Current world reserves of rare earths as assessed by the US Geological Survey are estimated to be about 120 million tonnes REO contained or approximately 200 years supply. The largest proportion of these reserves are in China (44 million tonnes) equivalent to 35% of the worlds reserves. Importantly the resources of heavy rare earths in china are less abundant and considered finite (<10 years) by the national authorities and hence are the subject of national controls.
Applications for Rare Earths are many and varied, but rare earth magnets and alloys make up almost half the market and exhibit the highest demand growth. Neodymium and Praseodymium, the rare earths used in magnets, comprise only a quarter of rare earths production but represent 80% of the total value in the rare earth market.