By Danielle Kaeding, Wisconsin Public Radio
More asbestos-like fibers have been discovered in rock samples from the Penokee Hills of Northwestern Wisconsin, where a company had proposed to build an open-pit iron mine.
According to a northern Wisconsin geoscientist, the greatest amounts of hazardous minerals are in the western part of the range, including the area that mining outfit Gogebic Taconite planned to develop before pulling out of the project earlier this year.
Northland College associate professor of geoscience Tom Fitz said there’s an approximately nine-mile stretch of the range with rock containing the long, slender “asbestiform” crystals. The crystals are a form of mineral known to be linked to mesothelioma, a rare type of lung cancer.
“In the stretch that’s in Wisconsin between the western part of the Penokee Range over to Ironwood, the area near Mellen, is the area that has the greatest potential to have the asbestiform variety,” Fitz said.
He said the asbestiform minerals show up in the Tyler Forks River and become abundant in some areas between there and southwest of Mellen.
Differences in geologic heat when the minerals were formed account for the variation in some parts of the range, Fitz explained. Not all so-called amphibole minerals are known to be hazardous, he said — just those that got hot enough to form into the long, slender asbestiform crystals.
“I don’t know exactly where the amphibole disappears in there, but it certainly decreases between Upson and Ironwood,” he said, cautioning that it could still be found in smaller veins across the entire range.
Fitz said more research is needed to determine what affect mining in the Penokee Hills could have on public health.