Mankind is using a greater variety of metals in greater quantities than ever before. As a result there is increasing global concern over the long-term availability of secure and adequate supplies of the metals needed by society. Critical metals, which are those of growing economic importance that might be susceptible to future scarcity, are a particular worry. For many of these we have little information on how they are concentrated in the Earth’s crust, how to extract them from their ores, and...
