Based on pertinent scientific papers, published reports, and chemical elements, REMs (or REEs) are composed of a set of 17 chemical elements as listed in the Periodic Table. Furthermore, the 17 rare earth materials include 15 lanthanides, plus scandium and yttrium. Scandium and yttrium are rare earth elements because they tend to occur in the same core deposits as lanthanides and exhibit identical chemical properties.1
Despite billions of years of being subjected to the physical extremes of geological processes – repeated melting and resolidifying, mountain formation, erosion, and immersion in sea water, the rare earths have not separated out into elemental minerals. This is a strong testament to the similarity of many of their physical and chemical properties.3
Considering its name, rare earth element is not very rare in crustal composition. Although each element has different abundance in the earth crust, the most abundant element (cerium) has a concentration more than copper or lead (and all other elements) except promenthium; and more abundant than silver, gold, or platinum. The difference between most and least abundant elements may be up to several magnitudes, and in many cases, more than 80% of the total rare earth element (REE) in REE deposit composed of La, Ce, Pr, Nd.4
Due to their application, Rare Earth Elements (REEs) are indispensable in modern material and energy technologies. Despite their relatively low usage quantities in material production, their exceptional mechanical, magnetic, electrical, and optical properties render them as the “vitamins” and “seeds” of materials.5 The prominent usage areas of rare earth elements are provided in the following graph6 (Figure 2).
Rare earth has attracted a lot of interest and is widely used in many fields for its
