Lake Superior Primary Bog Iron Ore

I'm just back from four days camping at Pancake Bay Provincial Park. This is located about 200 km north of Sault Ste. Marie, along the lower eastern edge of Lake Superior. 

'Rocks and Trees and Trees and Rocks... and Water' (1)

The Canadian Shield. Granite + Bogs = Primary Bog Iron Ore ?

Well maybe. If you can find the chain of geography that can result in a viable deposit. 

On Wednesday (August 21) I made the short 3.5 km hike along the established trail at the very north end of the camping sites. This trail starts along the modern beach area, and runs along a succession of ancient marine terraces, ancient shore lines. Near the end of the circuit, the trail crosses a wide open bog area, described as a 'fen' (2). This because water feeds into and then out of the area, mostly covered with low plants, with a few narrow gaps of water visible.

In the open fen, the small water channels displayed the typical visual signs suggesting the formation of iron oxide etched from the underlying bedrock.

The water itself had a reddish brown tint to it. On the surface was an oil slick effect (caused by molecule thick layer of iron oxide). There were thin films of a rust red slime like deposit were visible here and there.

The fen was drained by a small stream, bubbling down over rocks from the ancient shore lines as this dropped towards the modern lake.

Along the stream margins, in places where there were pools and level sections, there were small amounts of iron oxide deposited.

The deposits, although visible along much of the margins, were just too thin to allow useful gathering. There were two places (one shown above) where it appeared that water flowed seasonally, allowing for more of the material to build up. The layer of iron oxide seen above was still only about 1 cm thick.

One small spot had a significant deposit :

Tucked under the edge of a board walk crossing the stream, was a triangular fan of thick iron oxide.

The deposit was water saturated, and had a consistency about like pudding. At some point someone had stepped into the ‘goo’ (clearly seen in the middle of the image above). At this spot, the depth of the deposit was about 10 – 15 cm deep. It tapers out to about 1 cm thick at the stream edge (to the lower edge of the image). The deposit formed a triangle roughly 100 cm long the longest (lower) line. On a guess the total would have been at best about enough to fill a standard 20 litre pail. At best (when dried) this might have been just barely enough to supply a single small iron smelt test.

Because the ore was contained in a Provincial Park, resource gathering is not permitted. Initially several samples were gathered from various locations, to a total (saturated) of 260 gm. From the heavy deposit, a second sample of 410 gm was taken.

I was very happy that the initial observation of the signs of bog ore creation lead to the eventual discovery of a potentially useful deposit. Truth is that there are a lot of variables that effect an actual physical deposit of ore.

1) The Arrogant Worms : https://www.youtube.com/watch?v=eKJfLJREdEg

2) https://en.wikipedia.org/wiki/Fen