Athanasios K. Karamalidis, PhD, is an Associate Research Professor of Civil and Environmental Engineering at Carnegie Mellon University, Pittsburgh, USA, and an Oak Ridge Institute for Science and Education Faculty Fellow with the United States Department of Energy. Roderick Eggert, PhD, is Professor and Viola Vestal Coulter Foundation Chair in Mineral Economics in the Division of Economics and Business, Colorado School of Mines, USA, and Deputy Director of the US Department of Energy-funded research consortium, Critical Materials Institute.