Four elements do most of the work in a rare earth magnet

There are seventeen rare earth elements, and the industry does not treat them as one material. Lanthanum and cerium are the abundant pair and go into catalysts, glass polishing and fluid cracking. Neodymium and praseodymium are the workhorses of the permanent magnet trade, and their oxide — sold as NdPr — is the commodity whose price the U.S. government now floors at $110 a kilogram.

A neodymium-iron-boron magnet turns electricity into motion, which is why it sits inside an electric vehicle drive motor, a wind turbine generator, a robotics actuator, a guided munition and a hard drive. Samarium-cobalt magnets take the jobs that demand heat resistance. Dysprosium and terbium are added in small amounts to keep a neodymium magnet from losing strength as it heats up — the high-coercivity grades used in traction motors and wind generators.

That last sentence is the whole export control story. Magnets made only from light rare earths move through Chinese customs without a license. Add terbium or dysprosium and the shipment needs approval, because those two elements are heavy rare earths, they are scarce outside China, and separating them is the step the United States is only now financing at Mountain Pass.

The processing is the bottleneck, not the geology. Rare earths occur together in the same ore and behave almost identically in solution, so separating one from another takes hundreds of sequential solvent-extraction stages, each one tuned by an operator reading density, acidity and temperature. That is why a country can hold a world-class deposit and still ship its ore abroad for separation.

For miners, that chemistry sets the safety program. Separation circuits handle acids and solvents, the ore carries thorium and uranium in some deposits, and the crushing and milling side carries the same respirable dust hazard as any metal/nonmetal operation. The equipment is familiar. The material is not.