“Pennsylvania sits on a vein of sedimentary rock known as the Marcellus Shale, which is rich in natural gas. The geological foundation was deposited almost 400 million years ago by volcanic activity, and it contains lithium from volcanic ash.

Over vast stretches of time, deep groundwater has dissolved the lithium in these rocks, essentially ‘mining the subsurface’, according to Justin Mackey, a researcher at the National Energy Technology Laboratory in Pennsylvania.

Mackey and his colleagues have now found that when wastewater is dredged up from the deep by fracking activities, it contains an astonishing amount of lithium.”

From ScienceAlert.