Critical metals and strategic resources

The level of criticality of a resource reflects both the risk of supply and the importance of the resource. Although critical metals are not the rarest in the earth's crust, geochemical and mineralogical concentration processes are less efficient than for other elements such as silver, gold or mercury, yet control the geological environments in which they can be found. Three examples are presented: phosphates, lithium and rare earths. They are characterized by growing needs, by the concentration of production in a limited number of countries, and by recycling that is either non-existent or still in its infancy. As such, they provide food for thought on the sustainability of mineral resources.