Success is dependent on whether the U.S. can quickly scale up processing and refining after the mining of the resources, and compete on cost with a magnet-making and processing market that's heavily dominated by China. Once extracted from mines, rare earths are shipped to separation facilities, where they are separated from other minerals.
While China is dominant now, in the decades before the 1980s it was the U.S. that held a majority stake in this metals market. That changed as production growth abroad and mounting environmental pressures at home shifted production overseas and also offered cheaper labor costs., China "strategically flooded the global market" with rare earths at cheaper prices to drive out and deter current and future competitors.
The three most important materials used in magnets include neodymium, dysprosium and terbium. Terbium is one of the toughest to come by because production, extraction and magnet-making are focused on China. Trade wars and retaliatory tariffs can leave many companies sourcing these crucial materials in limbo, even if they make up just a small portion of a product.
I still can't believe that this samantha_subin was willing to cover growing bacteria on potato water for REE extraction in this article, but didn't bother to mention other producers ramping up like $VTMXF vital_metals. Or even $AREC. I guess it was early. Or holds $MP.