The ‘Critical metals’ increasingly underpin advances in digital technologies and in the development of renewable and sustainable energy sources and storage solutions. This unit aims to examine some of these commodities, focussing particularly on lithium and other ‘battery metals’, the Rare Earth Elements, and tantalum-niobium. The objective is to understand the geological setting and distribution of these strategic resources, and the geochemical processes that lead to the enrichment of the ore metals in the Earth’s crust. Critical metal resources formed in igneous, hydrothermal, and surface weathering environments, including salt lake systems, are examined in practical assignments and a short field trip.