Mountain Pass is the only large-scale rare earth mine operating in the United States and one of the world’s largest producers of light rare earths. Dysprosium and terbium are two of the most strategically important heavy rare earth elements. Who Will Build the Rest of America’s Rare Earth Supply Chain? REalloys owns 100% of Hoidas Lake heavy rare earth mine in Saskatchewan,CanadaAnd a 15-year supply arrangement for rare earth concentrate from the Tanbreez Project, one of the world’s largest rare earth deposits outside China. The project would make Tooele Army Depot the first U.S. military installation to host commercial heavy rare earth processing.