Rare earth elements (REE) include the lanthanide series (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) plus Sc and Y. All these metals occur together in different types of REE deposits such as carbonatites, alkali syenites and monazite-rich placers, and are found in more than 250 minerals in the Earth’s crust. The future of the world’s green technologies depends upon their availability and supply. At present, China is responsible for 80% of global REE production. However, countries such as USA, Australia, India, and Kazakhstan also extract and refine significant quantities of REE. These metals occur in primary deposits associated with igneous and hydrothermal processes, and secondary deposits concentrated by sedimentary processes and weathering. However, other types of resources such as ocean bottom sediments, waste rocks in closed mines, river sediments, industrial wastes like red mud, coal, and fly ash have proved to be containing significant amounts of these elements. Besides the beach sand deposits, the Amba Dongar carbonatite complex, and carbonatite plugs hosting REE deposits at Kamthai have been recognized as a potential REE resource in India. Significant concentrations of REE were identified in the deep-sea sediments of Afanasy Niktin Seamount in the Indian Ocean. Integrated exploration methods are playing a key role in the search for new REE mineral deposits. During geochemical exploration studies, portable analytical instruments such as pXRF, pLIBS, portable Raman spectrometer, and a couple of nuclear techniques have enabled successful results in recent times both on and off the land at lower costs, and allowing rapid decision-making on exploration strategies directly in the field.
