The shift to cleaner power needs resources from China. An export ban just cut off some supplies.

In 1886, a French chemist dissolved holmium oxide in acid. Then, he added ammonia. Toiling over the marble slab of his fireplace, he repeated the procedure dozens of times.

Finally, voilà: He’d extracted a new element.

More than a century later, Paul-Émile Lecoq de Boisbaudran’s painstaking discovery — which he named dysprosium, from the Greek for “hard to get” — is a crucial ingredient in the powerful magnets used in wind turbines and electric vehicle motors.

If the world is to succeed in its efforts to slow global warming, it will need dysprosium. It will also need a suite of other rare earth elements and minerals that many of us first heard about this week when China announced export controls that would effectively cut off the global supply of seven rare earths.

China’s export ban, part of the

Keep reading this article on The New York Times Energy & Environment.