Critical minerals from primary and secondary geological sources, and their recovery - extraction with Indian examples

Critical minerals have a global demand due to their important/strategic applications in many high-tech industries, such as the greenrenewable energy, electricals and electronics, telecommunications, superalloys, nuclear, space, artificial intelligence, defense, etc.The list of CMs is dynamic and depends upon the availability and perspective of each country, based upon the issues like geological scarcity, geopolitical considerations, trade policy, problems in supply chain, and other factors.CMs can be broadly grouped into: (i) Rare Earth Element (REEs); (ii) battery metals (Li, Co, Ni, Mn, Graphite); (iii) alloy metals (Ti, V, Cr, Ni, Nb-Ta, Sn); (iv) nuclear metals (U, Th, Zr-Hf, Be); (v) precious metals (Au, Ag, platinum group metals); (vi) toxic metals (Pb, As), and (vii) fertilizer commodities (phosphate, potash).Geologically, they are recoverable from diverse materials of rocks, ore minerals, mineral concentrate, sands, etc., with their sources being either primary or secondary.The primary sources for CMs were deposited during period(s) of mineralization in a wide variety of rock types.When such primary sources of rocks and ore deposits (constitute a provenance) were subjected to alteration, due to weathering or other surficial processes resulting from descending surface waters, it gave rise to the secondary sources of CMs like the supergene deposits of laterite, overburden, conglomerate, and placers of different types.Indian examples of the primary and secondary geological sources for CMs and their recovery and extraction are presented.