February 10, 2013 by Joseph Skulan
A disturbing feature about the plans for an iron mine in the Penokee Hills near the shore of Lake Superior is that so little information about these plans has been made public.
To date, Gogebic Taconite (GTac), the company that claims it intends to build the mine, has refused to answer questions as basic as the exact location of the mine, the chemical composition of the rocks the mine will disturb, and locations where overburden and tailings produced by the mine will be stored.
Even more disturbingly, the small amount of information that GTac has released about its plans is contradictory and appears to be aimed at deception rather than communication.
Below is a diagram of the proposed Penokee mine shown by GTac Mining Engineer Tim Myers during testimony at the only public hearing on SB1/AB1 on January 23, 2012 . It is one of what appears to be only two illustrations of the mine that GTac has yet made public, and has been widely circulated by mine proponents as evidence that the mine will not significantly disturb the Tyler Slate, a sulfide-bearing rock unit above (to the north of) the taconite targeted by the mine:
As illustrated in the next two figures, the GTac diagram is deceptive in two ways.
First, the GTac diagram exaggerates the vertical relief of the mine area by more than 50%, making it appear that more taconite can be mined without disturbing surrounding rock than in fact can be mined.
Second, the diagram grossly exaggerates the thickness of the taconite-bearing Ironwood Formation.
According to a 1978 report by Ralph Marsden, the Ironwood formation in the area of the proposed mine is about 650’ thick. GTac President Bill Williams himself has said that the Ironwood in the mine site is “600-700’ thick.” However, in GTac’s diagram the Ironwood is about 930’ thick. This discrepancy allows GTac to depict the mine as being almost entirely contained within the Ironwood formation. In fact, when the GTac diagram is redrawn with the Ironwood at its correct thickness, a large part of the north side of the mine is in the Tyler Slate.
This discrepancy is significant since much of the discussion about the possible environmental consequences of the Penokee mine has centered on pyrite in the Tyler and the sulfuric acid that would be produced if this pyrite were disturbed by mining activities. How much Tyler Slate will be uncovered by the mine depends on the width of the mine and the angle of the north wall of the mine, details that GTac has refused to release to the public. However, it does not appear to be possible to construct the mine depicted in the GTac diagram without removing a substantial volume of Tyler Slate. An excellent analysis of the current GTac diagram has been published by Woods Person.
In short, GTac appears to be attempting to make the Tyler Slate (and its troublesome pyrite) go away simply by calling it something else.
Moreover, there is no reason to assume that the mine depicted in the GTac diagram is the mine that actually would be built. The depicted mine leaves a large volume of easily accessible taconite on the mine’s north wall. Were the mine widened to recover this taconite, a greater volume of Tyler would need to be removed.
Bjornerud et al. (2012) discuss possible environmental effects of a mine that maximizes taconite production by placing the base of the north wall on the Tyler-Ironwood contact. This placement is supported by the illustration of the proposed mine that GTac was circulating in 2011, before the issue of pyrite in the Tyler Slate was widely known (Fig. 4). In this diagram, the base of the north wall of the mine is at the Tyler-Ironwood contact, just where Bjornerud et al. put it. The Bjornerud report follows Cannon et al. and sets the thickness of the Ironwood at about 500′, not 650′, but this difference in estimated thickness has no effect on the volume of Tyler Slate that the mine would remove, so long as the entire north wall of the mine is in the Tyler, as the original GTac diagram shows it will be.
GTac’s attempt to deceive the public about how much Tyler Slate will be disturbed by the mine casts doubt on the company’s honesty about another potential problem: the Yale Member of the Ironwood Formation. The lower third of the Yale member is composed of a pyritic carbonaceous slate that lies between the upper and lower taconite ores.
In the one core from the Penokees that is publicly accessible, taken about ten miles east of the mine site, the Yale member is rich in sulfides, with pyrite concentrations of more than 15% in places. While most of the discussion of pollution from a Penokee mine has focused on sulfides in the Tyler, the Yale member may pose an equal or greater danger. Moreover, the location of the Yale member between the taconite beds makes it impossible to avoid disturbing it while mining those beds.
Whether the Yale is as pyrite-rich in the mine site as it is a few miles to the east is not publicly known.
But GTac knows. GTac has access to more than 250 cores of the Penokees taken in the 1950s and 1970s by US Steel.
I recently asked Bill Williams about these cores
JS: You’ve looked at the US Steel cores?
JS: Is the Yale member in the proposed site?
JS: How much pyrite is in it?
BW: I haven’t seen any.
JS: You have not seen any pyrite?
Of course, not seeing pyrite and pyrite not being there are two different things, as I suspect Williams knew when he answered my question.
Given GTac’s past deceptions, Williams’ ambivalent semi-denial of the existence of a pyrite rich layer in the taconite is hardly reassuring. GTac could put an end to speculation that there is such a layer very easily, simply by making the USS Steel cores available for public inspection.*
The fact that GTac refuses to do so speaks for itself.
*As can be heard in the video, when I asked Williams if he was willing to make the US Steel cores available for public inspection, he and the GTac lobbyist Bob Seitz refused to answer the question directly, merely saying that such information would be released during the mine permitting process and suggesting that asking for it now is premature. However, there is nothing in the mining bill that will force GTac to release all of the information it has. GTac’s past secrecy suggests that there is no reason to assume that it ever will release more information than it is legally required to release.