WITH A SWEEP of his presidential pen Donald Trump has launched a surely fevered race, above all against China, to Earth’s last frontier in search of valuable minerals. His executive order on April 24th authorising seabed mining is intended to free American companies from international constraints and let them hoover up rock nodules the size of goose eggs (pictured) that are rich in nickel, copper, cobalt, manganese and other minerals, and that are abundant on some parts of the ocean bottom.