Of metals and market forces

ALL that glisters is not gadolinium. Even so, that mineral and its 16 “rare earth” cousins—found in everything from batteries to catalytic converters—do help make the modern world go round. And, as the world's manufacturers of such products have been reminded recently, China has a chokehold on their production.

China's grip on rare earths first made headlines in 2010, when it suddenly cut exports to Japan. But it had been squeezing the market for years. In 2000 it exported some 47,000 tonnes of the stuff; by 2010 it exported only about 30,000 tonnes. This decline appeared to be the result of unfair export taxes and quotas.