Tuesday, February 21, 2012

Updated: Letter: Scientists offer evidence of sulfides in Penokee mine site

To the editor,

Definitive evidence exists that sulfides are present in the Penokee mine site, possibly in sufficient quantities to pollute the Bad River Watershed with acid mine drainage. In fact, the presence of pyrite (iron sulfide) in the Ironwood Formation was noted in a Wisconsin Geologic Survey in 1929 (Aldrich, 206-212) and again now by three active geologists.

To create a separate ferrous mining bill that allows a mining company to "do their best" if they encounter sulfides and disallows scientists to testify in contested case hearings is irresponsible stewardship of our state’s natural resources. Sulfides can occur anywhere, and when combined with iron (as in pyrite), oxygen, and water, the result is sulfuric acid. In his testimony at Friday’s (Feb. 17 in Madison) Joint Finance Committee hearing, Jason Huberty (MS Geology) explained that you can’t distinguish between ferrous and nonferrous ore. By doing so, as in the proposed law AB426, the existence of sulfide minerals in the iron ore is hidden (With).

Why, then should iron mining be excused from so many rules when, in fact, the risk of acid mine drainage is present?

When Gogebic Taconite explains that no chemicals will be needed in their mining operation, they are not talking about mining but about the processing of the taconite -- separating magnetite from the ore using water and magnets after that ore has been mined. But, it is the actual mining of the ore -- blasting the overburden and removing the ore from the earth -- that exposes the pyrite to water and air at a much faster rate than would occur naturally, thus accelerating the acid production.

Marcia Bjornerud, PhD, Geology Professor, Lawrence University, after studying the area for 25 years, discovered that there are sulfide minerals in the overburden directly above the iron deposit targeted by the proposed GTac mine. When that waste rock is removed and then stored in piles in the mining process, the disseminated pyrite in the fragmented rock would over time be oxidized and interact with rain and snow, leading to acid drainage (Bjornerud).

Further, geochemist Joseph Skulan testified that after personally analyzing samples of the rock, some of which contained 20 percent pyrite, he concludes that billions of gallons of sulfuric acid could be produced (With).

In conclusion, because of sulfides present, the potential exists for acid mine drainage from the GTac mine into the Bad River Watershed. Therefore, it is irresponsible to enact a law, such as AB426, which separates ferrous and nonferrous mining, since both types have the same potential for environmental damage.

Thank you for your attention to this matter.


Aldrich, H.R., 1929. The Geology of the Gogebic Iron Range in Wisconsin. Wisconsin Geologic survey.

Bjornerud, Marcia. 12/18/2011, savethewatersedge.com.**

With, Barbara. 2/18/2012, "Façade of 'Responsible Mining' Crumbles; New Mining Bill Proven to Mislead the Public."*

Wendy Thiede
Oma, WI

*Editor's Note: See also a video clip of the two geologists' testimonies at the Feb. 17, 2012, meeting in Madison.

** Update/clarification: Dr. Bjornerud made these comments after the Assembly hearing in December 2011 (in West Allis, near Milwaukee), not at the Feb. 17, 2012, hearing. They were posted Dec. 18, 2011, on

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