Talon Metals has asked the Minnesota Department of Natural Resources for permission to drill more exploratory borings at its Tamarack copper-nickel mining project near the Aitkin-Carlton county line. The request comes just after the DNR approved Talon's plans to re-explore several of its existing borings.

On Nov. 22, Talon submitted an exploration plan with the DNR detailing plans to drill exploratory borings in bedrock at four sites on active state nonferrous metal mineral leases about 1/2 mile north-northeast to about 3.5 miles north-northeast of Tamarack.

The borings would be drilled using the diamond core drill method and be temporarily or permanently capped upon completion in accordance with Minnesota Department of Health regulations.

The DNR has 20 days from the Nov. 22 submission to approve or deny Talon's plan.

Both explorations would take place on state mineral leases controlled by Kennecott Exploration Company, a subsidiary of mining giant Rio Tinto, but Talon is Kennecott's designated operator for the exploration. The DNR has approved the operating agreement between the two companies, the exploration plan said.

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Talon has entered into an agreement with Kennecott to acquire up to a 60% interest in the Tamarack project. Talon currently owns 17.56% of the project but has taken over management and operatorship, company officials said.

Kennecott is also leasing state mineral leases south of Tamarack and Highway 210. Those leases stretch southeast into Carlton County near Automba.

The deposit, known as the Midcontinent Rift's Tamarack Intrusion, was first drilled by the Minnesota Geological Survey in 1984. Kennecott Exploration began exploring in 1999 and made a discovery of high-grade copper there in 2008. However, the global recession killed copper prices and virtually halted new exploration there for several years. In 2014, Talon started to buy into the Tamarack project.

Copper-nickel mining has never been done in Minnesota and remains controversial. Opponents say the mines would pollute nearby waters with toxic waste.

Last year, PolyMet became the state's first fully permitted copper-nickel mine, though it still needs to raise almost $1 billion in financing and faces numerous legal challenges, which resulted in a court placing several of its permits on hold.

While PolyMet was the first copper-nickel mine to receive a permit, it could be the first of several in northern Minnesota.

Twin Metals, which is planning an underground copper-nickel mine and tailings storage facility within the same watershed as the Boundary Waters Canoe Area Wilderness, is expected to file a formal mine proposal soon.

Like Talon and Kennecott, several other companies have made regular exploratory drillings in Minnesota — Teck near Babbitt, Vermillion Gold near Gilbert and Virginia, Encampment Minerals near Birch Lake and Hoyt Lakes and AngloGold Ashanti Minnesota throughout St. Louis, Itasca and Koochiching counties.

An earlier version of this article incorrectly described Talon's ownership of the Tamarack project. It has been corrected.