Now, in a cosmic practical joke on environmentalists, researchers say they've found a lithium mother lode -- in Pennsylvania fracking wastewater. It turns out that the Marcellus Shale -- a long swath of sedimentary rock in the northeastern United States that holds huge amounts of frackable gas -- holds huge quantities of lithium too. Justin Mackey and other researchers at the National Energy Technology Laboratory in Pennsylvania were pleasantly surprise when they studied the contents of wastewater dredged up in the fracking process at 515 sites in the Keystone State, reports Science Alert.