Meet a US startup trying to break China’s rare-earth monopoly

Every few hours, two furnaces in a New Hampshire office park quietly transform batches of taupe-colored powder into rough ingots. These mottled chunks of metal, about the size of a few bricks, ultimately will be used to make electric vehicle motors or maybe a fighter jet.

This is what rare-earth processing looks like in the United States, where university researchers and startups are trying to wrest a slice of this small but vital industry from China.

Rare earths are a family of elements toward the bottom of the periodic table, with tongue-twister…