USGS gets excited about lithium in northern New England

New Hampshire has long been known for granite but our connection to another mineral, lithium, has long been pretty minor. It consisted mostly of a long-forgotten health tonic called Londonderry Lithia that was naturally infused with the substance. The company thrived as part of a short-lived health fad for “lithia water,” but collapsed in the 1920s following revelations that any benefits were exaggerated.

Lithium might return to prominence here, however: The U.S. Geological Survey study released Wednesday says the three northern New England states sit on 900,000 metric tons of lithium, which has soared in value as lithium-ion batteries have become the powerhouse of the electric age. USGS says the whole Appalachian region from Maine to George has enough lithium that can be economically mined to replace 328 years of U.S. imports.

While most of the known northern New England lithium supply is in western Maine, New Hampshire might also have its share because lithium is found in pegmatites, a term for coarse igneous rocks formed when hot magma cools. And the most common source of pegmatites is granite.

It does not appear that New Hampshire has ever had any mines specifically seeking lithium but we do have a history of pegmatite mining for mica. Ruggles Mine in Grafton, which is still open for visitors today, is the best-known example.

Lithium is the best-known of the minerals needed for the energy transition because of its use in batteries. The U.S. has one lithium producer and imported more than half the lithium needed.

Lithium pegmatites in the Appalachian region have long attracted scientific attention, USGS noted. The Kings Mountain area of North Carolina was the site of the first large-scale lithium pegmatite mining in the United States, and large Maine deposits have been studied.  “The new USGS assessments build on that legacy with a more systematic, detailed approach,” the agency said.

Lithium-rich pegmatites in the northern Appalachians were formed when the mountains were formed, more than 250 million years ago when plate tectonics forced Africa, Europe, and North America together into a supercontinent named Pangea. “Pegmatites like the ones found in the Appalachian mountain belt are found in corresponding areas of Ireland and Portugal, both of which formerly bordered the Appalachians,” USGS noted.