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interesting and informative! Thanks!

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Richard, you've seen Frank Riehlicke's presentation on micromount zoom meeting I assume?? All the ring forming sulfides are Pb& Sb sulfs, except pyrite, (which wasn't the same kinda ring at all, I'd say). He said it was rutile at Potosi, you might ask him if any were tested for absence of Pb at least??

Could it be colored by one mineral while the rings are another? I bought one when I was into larger stuff. Got a scope, and much later realized I had a ring in my Potosi topaz. Just using a scope enlarges your collection.

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I hadn't seen that presentation, I'll look for it, Thanks. I knew about the boulangerite and other rings. It wasn't completely clear to me what the folks who mentioned goethite thought but I had the feeling they thought most of the needles might be open conduits lined by some iron oxide (really does not seem like that to me). And for sure about the microscope! I didn't get a decent one until 2015, and have been enamored ever since (and sorry I didn't get it much sooner). Haven't seen any rings in my topaz, but there's a lot to look at.

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Hi Richard. You can find it on my Youtube channel here https://www.youtube.com/watch?v=ErTj0vHau74&list=PLwdOHcjmducFKcDw8d2qgAoEEEB0M7vht&index=61&pp=gAQBiAQB

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Thanks - I actually had subscribed to your channel some time back, so it's mostly a matter of remembering to go look! I appreciate all you do!

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I truly enjoy The Geologic Column, Rich!

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Thanks!

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So colorful, interesting and intriguing - like all the postings in your Geologic Column. I used to be troubled by all the speculation and uncertainty in science, but have come to embrace mystery. We may never (or just plain can’t?) fully understand earth history at either macro or micro levels.

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I'd say that the goal of science is to reduce uncertainty, not necessarily to arrive at any absolute truth (but that would be OK!). Speculation and testing the speculations is a vital part of the process; geology without speculation would not be science. We try to eliminate the impossible and unlikely, and even the less likely, by using observable facts and known processes.

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