Largely as a result of high prices and tight supplies of rare earths, considerable efforts are also being made to find alternatives. Time and cost are key factors in the development of new rare earth resources but the development of new sources of rare earths is absolutely essential.
Contrary to their name, rare earth elements (or REE) are not so rare. The term “rare” was attached to these elements when they were first discovered in the 1800’s when they indeed appeared to be “rare”. However, REEs are so common that if one was to scoop some soil from one’s yards it would likely contain some amount of REEs. Rare earth elements are found throughout the world and some REEs are more common than tin and almost as plentiful as copper. The problem is not a lack of REEs in general, but rather a lack of rare earth deposits that have sufficient concentrations or REEs to make mining them economical. In other words, rare earth elements are not rare but large deposits of them are. The rare earth elements consist of seventeen metal elements – 15 elements from the lanthanide series of elements (atomic numbers 57 to 71) plus scandium (atomic number 21) and yttrium (atomic number 39). Scandium and yttrium are included in the rare earths since they are chemically similar to the lanthanide elements and are found with the lanthanide elements in nature. The 17 rare earth elements comprise the largest chemically coherent group of elements in the periodic table.