https://pubs.usgs.gov/pp/1802/o/pp1802o.pdf
United States From 2012 to 2015, the United States was a leading producer of rare-earth minerals outside of China. All mine production of REEs during this period was from Molycorp, Inc.’s Mountain Pass Mine in San Bernardino County, California. Mine production at Mountain Pass began in 1952 but was discontinued from 2002 to 2011 because of low rare-earth prices and environmental permitting issues. In 2012, Molycorp commissioned new mine and processing operations that had an initial planned (but never fully realized) production capacity of 19,000 metric tons per year of REOs. Because of substantial decreases in the market prices of the REEs, however, Molycorp idled operations at the Mountain Pass Mine in 2015. Exploration and development assessment projects in the United States include Bokan Mountain, Alaska; La Paz, Arizona; Diamond Creek, Idaho; Lemhi Pass in Idaho and Montana; Pea Ridge, Missouri; Elk Creek, Nebraska; Thor Mine, Nevada; Round Top, Texas; and Bear Lodge, Wyoming. Domestic reserves of REOs were estimated to be 1.8 million metric tons (Gambogi, 2015).
China floods market lowering prices, American producers price too low stop production. If china imposes tarrifs another American industry could roar back to life.