Rare earths (REE) are a group of 17 chemical elements comprising Scandium (Sc-21), Yttrium (Y-39) and the lanthanides: Lanthanum (La-57), Cerium (Ce-58), Praseodymium (Pr-59), Neodymium (Nd-60), Promethium (Pm-61), Samarium (Sm-62), Europium (Eu-63), Gadolinium (Gd-64), Terbium (Tb-65), Dysprosium (Dy-66), Holmium (Ho-67), Erbium (Er-68), Thulium (Tm-69), Ytterbium (Yb-70) and Lutetium (Lu-71). These special metals began to be discovered in the late 18th century, and Promethium was the last one to be discovered, in 1945.
Really, “rare earth elements are neither rare, nor earth”. The term "rare earth" does not refer to the quantity present in the earth's crust, but how complicated is, in some cases, to separate the element from the other minerals that accompany it, since it is very unusual to find rare earths in a pure form. They are grouped together as a family because of their incredible chemical similarities.
Close analogy to the chemical behaviour of rare earth makes their extraction process, and subsequent separation and purification, tedious and complex (in some cases can involve over 1500 steps). Notwithstanding, they are the elements that have become irreplaceable to our world of technology owing to their unique magnetic, phosphorescent, electric and catalytic properties.
The applications of rare earths are very diverse and constantly increasing. Nowadays they are used to produce computer hard disk drives, stereos, catalytic converters, fuel cells, permanent magnets, mobile phones, TV screens, touch screens, wind turbines, solar panels, ceramics or optical materials, among others. Their optical and magnetic properties have made them indispensable for the production of almost all modern equipment.
Although there are numerous rare earth reserves spread around the world, they are extracted from very few mines. In fact, nearly all of the world's rare earth production comes from China, and, specifically, from one deposit, Bayan Obo, located in Inner Mongolia, representing between 40% and 60% of total production. Just how dependent the entire world is on Chinese rare earths became very clear at the end of 2010 when China threatened to restrict supplies. The spike in rare-earth prices was very dramatic - up to 3,000% for some of them. Prices have since fallen back, but the shock was enough to prompt companies begin to explore producing and refining rare earths elsewhere in the world by recovering the production in abandoned mines, as has happened in the US and Australia, or developing new projects such as India, Brazil, Malaysia and Canada.