Abstract: The present application provides a process and system for extraction of rare earth elements using a long-term acid soak. In particular the present application provides a process for extracting rare earth elements from an ore by: (a) soaking the ore with a strong acid at a temperature of less than about 100° C. for at least 1 day; and (b) leaching the acid-soaked ore with an aqueous leaching solution to obtain a leachate comprising the rare earth elements. Optionally, a small amount of water is added to the acid during the acid soaking step and/or an additive comprising one or more metal ions is added to the acid during the acid soaking step.