Equally troubling was the more recent discovery by Tom Fitz, a geology professor at Northland College in Ashland, Wis., of a highly carcinogenic asbestos-form mineral at one of GTac’s sampling sites. The fibers of the mineral, which would be dispersed in blasting, are like tiny, breathable needles.

Last September, several hundred people gathered outside John F. Kennedy Memorial Airport in Ashland, a few miles from GTac’s mining site, to commemorate Kennedy’s 1963 speech, which called for legislation to protect the area’s natural resources and promoted its economic potential as a scenic region for recreation. One of the last to speak at the event was Mike Wiggins Jr., the chairman of the Bad River tribe and the mine’s most formidable opponent.

The Bad River fear the contamination of the fish they depend on for food and the destruction of sensitive wild rice beds that they harvest on the coast of Lake Superior. Mr. Wiggins has voiced his opposition to the mining legislation in private meetings with Mr. Walker, led Wisconsin’s tribes in demonstrations at the State Capitol in Madison and allocated hundreds of thousands of dollars of the Bad River tribe’s scant resources to legal fees to fight the mine.

The Bad River and several other tribes assert that the state has no right to permit the enormous mine without their agreement since the site lies in “ceded territory,” an area covering a large portion of Northern Wisconsin where tribal members maintain special hunting, fishing and harvesting rights enshrined in federal treaties. Last June, one of the tribes established an educational camp near the mining site to draw attention to how the mine would violate its treaty rights, as well as to highlight sustainable alternatives to mining. GTac responded to a minor altercation with protesters unconnected to the camp by hiring an Arizona-based private-security firm, which sent guards armed with semiautomatic weapons to patrol the mine site. (The guards have since been withdrawn; the camp is still there.)

In the Chippewa tradition, a decision is made based on how it will affect people seven generations forward. By contrast, the company’s optimistic estimate for the life span of the first phase of the mine is 35 years. Last summer Mr. Wiggins played Governor Walker a recording of Kennedy’s speech. Mr. Wiggins said that the governor appeared indifferent to Kennedy’s words; Mr. Walker has never wavered in his support of the mine.

Though GTac has already begun bulk sampling iron ore at the site, the mine still faces many hurdles before it can be permitted. The company has filed incomplete sampling applications with the state’s Department of Natural Resources. GTac’s president, Bill Williams, is facing a criminal inquiry in Spain for alleged environmental crimes, which are unrelated to the GTac mine. The charges state that runoff from an open-pit mine where he once worked as an executive contaminated local groundwater. (Mr. Williams denies the charges and declined to comment on them.) Most important, the tribes will almost certainly challenge the mine in federal court.

Mr. Wiggins and five other tribal leaders have already begun seeking redress from the federal government. Last August, they sent President Obama a letter asking him to direct the Interior Department to prevent the construction of GTac’s mine, citing their claims that the mine would infringe on their treaty rights.

Though the letter did not mention it, five years ago Mr. Obama told nearly 400 Native American tribal leaders, “We have a lot to learn from your nations in order to create the kind of sustainability in our environment that we so desperately need.” The president said that the tribes “deserve to have a voice” and “will not be forgotten as long as I’m in this White House.” Last week, Mr. Wiggins said that although he has gotten preliminary responses from two federal agencies, he is still awaiting an answer from the president.