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Trying to identify this rock found in Wyoming

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asked Sep 23, 2018 by darrell seyler (150 points)

4 Answers

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Best answer
Obsidian. Almost 100% sure.
answered Sep 24, 2018 by linkisnotzelda (5,390 points)
selected Sep 25, 2018 by darrell seyler
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Three possibilities suggest themselves right off the bat, obsidian, chalcedony and onyx.
answered Sep 24, 2018 by Weasel (58,980 points)
Is there such a thing as emerald green obsidian? . The rock is super hard wont flake very easy . I like ur answers ! Thank you
Obsidian technically could be any color, but black and brown is the most common variety. Much like other minerals, color can vary based on impurities in the minerals around it.
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I am also very confident this is obsidian but there remains other possibilities and I didn't want to exclude them.
answered Sep 25, 2018 by Weasel (58,980 points)
Sorry Weasel. I'm not trying to contradict you or anything. You've been here much longer than I have!
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No problem here. My goal is to get as many people coming as possible as often as they can. I personally go to mines, rock shows, fossil sites and museums. I have gone to geology centers but never had any geology instruction. I learned here from Herschel and from the internet and books I bought. I am a Lake Superior and Michigan guy. We have volcanic flows, a unique area in the Upper Peninsula where copper mines are, Lake Superior agates, rock moved by glacial action, water everywhere. Lake Michigan, Huron and Erie were inland seas. Lake Ontario and Lake Superior were formed by volcaic and tectonic action along a fault line which formed the Mississippi, too. We have unique stones in the greenstone, the petosky stone and the lake superior agate.
My rock stuff started with a three hundred pound puddingstone formed by alluvial flow and deposted here by retreating glaciers. I found jasper and a lake superior agate imbedded in the puddingstone. I took two other rocks from my yard to the geological center near here and a visiting professor said my stone was a two billion year old mudstone. I was hooked.
We have a fault line that runs from Lake Superior to the lower Peninsula. The earth's crust was ruptured there creating the lake Superior basin. The associated volcanic and seismic action in the Houghton area, the glacial flows and some of the oldest known mountains on the continent, the Hurons, make for a geological paradise.
I want everyone to enjoy them.as much as I do. I am not an expert but I learn everyday. How much more will a guy learn if you give him a choice and guide him through the tests he can use to identify his stone? Give him a starting point and then tell him about conchoidal fractures, what they mean about the rock, how they were used by primitive man, have him learn about translucent stones by backlighting, checking to see if it magnetic, if it glows, will it react with vinegar, the size of the crystals and grains. I never take offense to knowledge.
answered Sep 27, 2018 by Weasel (58,980 points)
That's really cool! I am still a junior high student, and I want to study geology one day. Living in the pacific northwest, there are zeolites everywhere, but I don't have the tools yet to collect most of them myself. I am glad that there are other people out there who enjoy rocks as much as I do! Thanks for being so helpful, I have learned a lot from this site and look forward to learning more! And sorry darrell for this long unrelated comment thread!

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