It is worth noting, however, that Mountain Pass primarily produces "light" rare earths, while the mines in southern China will remain the predominant source of

It is worth noting, however, that Mountain Pass primarily produces "light" rare earths, while the mines in southern China will remain the predominant source of several "heavy" rare earth metals for several years to come (e.g., dysprosium). That said, such a nuanced argument appears nowhere in the linked article.