U.S. federal and state researchers said there might enough lithium in the state of Arkansas to meet the entire world’s demand for the critical metal ingredient in modern batteries.

The New York Times reports that researchers at the U.S. Geological Survey and the Arkansas government announced on October 21 that they had found a vast reserve of lithium in an underground brine reservoir in Arkansas.

The researchers say there might be 5-19 million tons of lithium in a geological area known as the Smackover Formation. Several companies, including Exxon Mobil, are developing projects in Arkansas to produce lithium, which is dissolved in underground brine.

The Times said that the practicality of lithium harvesting in the region will depend on the ability of those companies to scale up new methods of extracting it. The processing technique that Exxon and others are pursuing in Arkansas, known as direct lithium extraction, generally costs more than more conventional methods do, according to the consulting firm Wood Mackenzie.

Most of the world’s lithium is produced in Australia and South America. A large majority of it is then processed in China, which also dominates the manufacturing of electric vehicle batteries.