Compared on a per kilogram basis, mining and refining some of the exotic metals used in modern technology inflict a lot of damage on the environment. Compared on the basis of their global annual production, the cradle-to-gate impact of metals is still dominated by the old-school elements iron and aluminum. That’s one of the bottom lines from a comprehensive environmental analysis of 63 metals, published in PLOS ONE. A unique aspect of the study is that it teases apart the environmental impact of each element, even though many are mined or processed in combinations. The detailed analysis could help engineers design products that substitute more benign metals.