Much coverage of the “rare earth metals” issue and the Chinese stranglehold on the global supply is deeply misleading due to failure to highlight one important fact. As Brad Plumer writes “Despite their name, rare-earth elements aren’t actually all that rare.”
Promethium is genuinely rare, but cerium is extremely common and in general locating deposits is not the issue. Rather, the mines where rare earth metals are produced are extremely polluting so the tendency is for nice countries to not want to dig them up. For a while, China just absolutely did not care about this and drove everyone else out of the market. Now China’s taking baby steps toward pollution consciousness and supply is being curtailed. The real question is whether other producers will want to get back in the game, either because they care less about pollution or because some new less gross extraction methods are developed.