When the rare earth castle came crashing down

New York

IN late 2010, two questions were on the minds of many commodities investors: What are rare earths? And where could they buy some?

The group of 17 obscure, difficult-to-pronounce minerals, used in hot-ticket items like smartphones, electric cars and wind turbines, were beginning to post the kind of price gains not seen even in the traditionally volatile energy and metals markets.