On the hunt for copper and other valuable metals, five exploration companies hope to prospect on 44,000 acres of the Superior National Forest near the Boundary Waters Canoe Area over the next two decades.
The details of their plans are described in a draft environmental review released last week by the U.S. Forest Service, which is seeking public comments on it.
If ore is discovered, it could bring new mining projects to the national forest -- a prospect that worries environmentalists and has been cheered by economic development officials in northern Minnesota.
The exploration is driven by high metal prices and hopes of finding copper, nickel, platinum and other ores in the heart of a geological formation called the Duluth Complex in Minnesota's Arrowhead region. If all 44,000 acres are explored, it would represent more than double the area previously prospected in the formation, industry officials said.
"Very little of the Duluth Complex has been explored," said geologist Ernest Lehmann, whose company is among five planning to look deeper into the formation using core-drilling rigs and other techniques.
For decades, geologists have been finding copper and other metals south of Babbitt and Ely, Minn., on the edge of the complex. That's where PolyMet Mining Corp. is proposing an open-pit mine, and Twin Metals LLC is considering an underground mine. Past exploration for metals in the interior of the formation hasn't been fruitful, Lehmann said.
"That doesn't mean it isn't there," said Lehmann, who estimated the odds of finding mineable ore at 100 to 1, which he considers good.
Geologists are armed with better data about the complex, said Dean Peterson, senior vice president for exploration at Duluth Metals Ltd., which is seeking permits to prospect on 16,500 acres of the forest.