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John Truax April 11, 2012 03:59AM
This does not look like Thomsonite from Thomsonite beach, Grand Marais, Cook Co., Minnesota, USA. I have seen nothing like this in many searches of the lava flows at the location. The zeolites in this area are found as seam fillings and nodules in basalt and consist of radiating crystals of various zeolites, this specimen appears to be a rock.
Stephanie Martin April 11, 2012 04:23AM
I agree, it looks like "bird's eye" rhyolite.
Dan R. Lynch April 11, 2012 07:32AM
I've seen this specimen before and thought the same thing. Definitely not thomsonite. I grew up just down the highway from Grand Marais and my dad has one of the world's largest stashes of Minnesota thomsonite, so I'm pretty familiar with the stuff.
Uwe Kolitsch April 11, 2012 04:23PM
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