A new U.S. Geological Survey assessment has identified the potential for significant undiscovered lithium deposits in a region spanning Maine, New Hampshire and the eastern half of Vermont. But there is uncertainty in the estimates, and a long way to go before any mining happens, according to geologists.
Lithium has become an increasingly important resource due to its use in batteries for electric and hybrid cars, as well as its ubiquity in phones and other electronic devices. But last year, the U.S. relied on imports for more than half of the lithium it used, according to USGS.
Because of that reliance on imports, along with the metal’s increasing economic importance, the USGS has put lithium on its list of critical minerals. The agency says it is pursuing assessments of potential lithium deposits across the country. It’s part of a larger, multiyear push to make the country more independent from imports of economically important minerals.
But whether Vermont has a role to play in the country’s lithium supply remains to be seen.
‘Vermont, you just don’t have a lot of ingredients’
The assessment, which was published in April, used available data to identify areas where the underlying geology and historical observations point toward the presence of lithium. Based on that data, a panel of scientists estimated how many undiscovered deposits of lithium were likely to exist in the region. The estimate of the number of potential deposits was then used to determine how many metric tons of lithium may be present in the region.
There is a 50% probability that Maine, New Hampshire and eastern Vermont contain at least 530,000 metric tons of recoverable lithium, the study estimated, meaning lithium that would be economically viable to extract. That estimate provides a first indication that mining companies may want to take a look at the region.
Even if deposits are found, geologists said it’s likely to be a slow road to any lithium mining in the region. And the potential sites for further exploration in the region would likely be in New Hampshire and Maine, not Vermont.
That’s because Vermont’s geology differs from that of its neighbors in ways that make it less favorable for the formation of lithium deposits, according to Niki Wintzer, one of the authors of the USGS study.
That’s in part because Vermont has fewer of what geologists call “evolved granitoids,” a kind of rock that is more likely to host the kind of lithium deposits the study focused on, according to UVM geology professor Keith Klepeis.
Or as Wintzer, one of the USGS study authors, put it: “Vermont, you just don’t have a lot of ingredients.”
In New Hampshire and Maine, the underlying geology points towards more potential for lithium deposits, Klepeis said. There is already a large, known lithium deposit in western Maine, although it has not yet been mined.
Hype meets uncertainty
While federal officials have touted the study as evidence that the U.S. could achieve greater independence from lithium imports, geologists said that the results need to be interpreted with care.
“It is a solid, scientifically based estimate,” Wintzer said. But, she added, “There’s a wide range of uncertainty.”
“Because fundamentally, we’re being asked a challenging question,” she said — the question of estimating deposits that haven’t yet been discovered. In other words, the study is making statements about what could be, not about what is.
Despite the uncertainty, Doug Burgum, secretary of the U.S. Department of the Interior, posted about the study on X last week.
“@USGS has found that the Appalachian region of the U.S. contains enough lithium to replace 328 YEARS of imports!” Burgum wrote, drawing on USGS estimates for both northern and southern Appalachia.
Geologists aren’t as quick to jump to that conclusion.
“They’re definitely not saying that they have found anything,” Klepeis said of the study. “They’re saying, ‘You know, if you look at the whole region, you know, what kinds of numbers are possible.’”
‘Nobody’s going to start ripping up the ground anytime soon’
There’s a long road from the USGS study to any actual mining, according to Klepeis.
The next step would be for mining companies or government agencies to conduct further exploration of potential lithium deposits, through field work and chemical assessments, Klepeis said.
“Nobody’s going to start ripping up the ground anytime soon,” he said. “This is like one of these preliminary studies, looking at probabilities. And it could change in the future, as more information comes in about where lithium occurs.”
While Vermont seems to be low on the list for exploration, if viable sites for mining are found across the border in New Hampshire, that could have economic, environmental and health impacts on both states, according to UVM geology professor Laura Webb. That’s because lithium mining can be energy- and water-intensive, and byproducts from the process have the potential to impact water quality, she said.
“It’s a potentially significant resource, for what we know right now is an important need,” Webb added.
“Will there be mining in the northeast? I’d say probably. A lot? Unclear. Probably not.”
