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Maine geologists discover potentially valuable deposit of critical minerals near Presque Isle

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A fine-grained volcanic rock (trachyte) that hosts rare earth elements, niobium, and zirconium, all which are considered critical mineral resources. This rock was found on Pennington Mountain in Maine. Image courtesy of Chunzeng Wang, University of Maine at Presque Isle.

A team of federal, state and University of Maine at Presque Isle geologists says it has found a rare deposit of potentially valuable minerals on part of Pennington Mountain in Aroostook County.

These elements are on a list of several dozen critical minerals that federal officials say are important for manufacturing electronics and defense systems.

Amber Whittaker, a senior geologist with the Maine Geological Survey, said this is a collection of critical minerals that aren't usually found in such large amounts in any one place.

"Getting a minable concentration of them are rare," she said. "We want them to minable because we use them in so many high-tech consumer products, like cellphones, computer hard drives, electric vehicles, hybrid vehicles."

The discovery was made through a partnership of the U.S. Geological Survey and Maine Geological Survey, which have been mapping northern parts of the state by flying aircraft to collect high-resolution data.

The goal of the mapping project is to find undiscovered critical mineral deposits that could be minable, a goal for U.S. policymakers.

Chunzeng Wang, a geology professor at the University of Maine at Presque Isle, visited the Pennington Mountain site to collect more rock samples and then sent them to a lab for more analysis.

He said he has never seen such a high concentration of rare earth minerals in one place before.

"It's the first hard rock type, rare earth deposit ever discovered east of the Mississippi River," Wang said.

Thanks to this discovery, there will be more opportunities to fly airborne geophysical surveys over parts of Maine, Whittaker said.

"Right now we think that there aren't many of these occurrences, but there really could be because we haven't been able to cover all of that ground," she said. "And we haven't had the type of data that helps us basically see through the trees and see through the materials on the ground to see whether there are rocks like this.

More exploration must be done to determine whether this area is an economically significant deposit.

It would be up to Maine's Land Use Planning Commission to rezone the area if mining were proposed. Any mining proposals would have to meet strict state environmental standards.