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Hey guys, Forgive me for my lack of knowledge when it comes to this subject, but I was recently hunting through some shale piles at Florissant when I found an ironstone concretion, unattached to any shale. It feels lighter than most stones of the same size. It was really bizarre, and when I asked one of the owners about it she said it was a 'fireball' thrown from the Guffey Volcano. This was strange to me because the fireballs that I am used to seeing are the chunks of pumice in the shale. Here is one from my own collection: Here's a close up showing the little black bits of volcanic glass (?) in it. For comparison, here is the ironstone concretion with what looks like tephra showing from a crack in the nodule. To simplify my question(s), what is the difference between these two 'fireballs', what are they made of, why the difference in preservation? If they aren't fireballs, what are they? I'm really interested in this and I hope you guys can shed some light on it. Any additional info is appreciated, I'm anxious to learn more! As always, thank you, I'm very grateful for your informative responses.

Yellowstone spawned twin super-eruptions that altered global climate, Geological Society of America, October 26, 2017 https://www.sciencedaily.com/releases/2017/10/171026085804.htm http://www.geosociety.org/GSA/News/Releases/GSA/News/pr/2017/17-60.aspx Santa Barbara Basin Sediment Record of Volcanic Winters Triggered by Two Yellowstone Supervolcano Eruptions at 639 ka https://gsa.confex.com/gsa/2017AM/webprogram/Paper306169.html Yours, Paul H.