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Post by Jugglerguy on May 22, 2012 19:07:38 GMT -5
My son and I went to a local place that makes concrete blocks today. They dig sand out of a pond, remove the rocks and put them in a huge pile. The owner told me that a lot of people come to look for rocks, so it's pretty picked over. We did find a few interesting rocks though. We got about a dozen small Petoskey Stones, a few pudding stones, and what might be a piece of chain coral. The possible chain coral is soaking in acid right now. The following rocks were interesting, but I don't have any idea what they are. All were photographed wet.
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Deleted
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Post by Deleted on May 22, 2012 20:17:03 GMT -5
I'm wondering if the inclusions in the center photo might be datolite and/or thomsonite.
I'd like to think that the big green spot on the rock at the bottom was chlorastrolite, but I'm not sure how people dig them out of the basalt.
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shermlock
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Post by shermlock on May 22, 2012 20:21:52 GMT -5
Center picture appears to be gowganda tillites...at least the bottom one and the one on the left. Scott
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Post by Jugglerguy on May 22, 2012 20:30:09 GMT -5
Wow, you're much more optimistic that I am, rocks2dust. I doubt that these rocks contain anything as rare as datolite, thomsonite, or chlorastrolite. Those are all pretty rare from what I understand. Doesn't datolite only show up as nodules? I also thought it was mainly found in the Kewenaw Peninsula. I'm in the lower Peninsula.
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Post by Jugglerguy on May 22, 2012 20:57:28 GMT -5
I picked up a couple of gowganda tillites today too. I didn't think they were those colors. This is what I thought gowganda tillite was: I thought that, because that's was it looks like in a book I have. Maybe they come in other colors.
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Post by Deleted on May 22, 2012 21:41:09 GMT -5
Wow, you're much more optimistic that I am, rocks2dust. I doubt that these rocks contain anything as rare as datolite, thomsonite, or chlorastrolite. Those are all pretty rare from what I understand. Doesn't datolite only show up as nodules? I also thought it was mainly found in the Kewenaw Peninsula. I'm in the lower Peninsula. Yeah, you can mark me as an optimist. Some sort of pudding stone is probably correct. The difference in colors found in the same locale just made me wonder if it couldn't be something more than conglomerate. Its been many decades since I've been in the UP, but I know that with glaciation (not to mention whatever the block co. may have hauled in), ship ballast, etc. rocks do travel. So, point taken, I just saw some rounded edges and variation that made me want to see closer and suggest some possibilities.
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Minnesota Daniel
freely admits to licking rocks
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Post by Minnesota Daniel on May 22, 2012 23:12:48 GMT -5
The first is probably vesicular rhyolite. Of the next three, the upper right looks like amygdaloidal basalt filled with epidote. The other two also amygdaloidal basalt -- the orange is maybe feldspar, laumontite, Thomsonite, the greenish white maybe quartz, prehnite, olivine? The last looks to me like diabase.
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Post by Jugglerguy on May 23, 2012 5:44:55 GMT -5
Thanks Daniel, I'll have to do some studying. You've given me some good places to start. You mentioned Thomsonite as rockstodust did. I was under the impression that Thomsonite was extremely rare. I also thought they were individual little rocks, not parts of other rocks. Then again, I know very, very little about rocks, but I'm learning!
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Post by Drummond Island Rocks on May 23, 2012 8:31:58 GMT -5
We just talked about thompsonite at our kids rock club meeting last week. There were a bunch of samples showing how its encased in basalt. I asked how they remove the thomsonite from the host rock and was told with a hammer. I guess the basalt is softer then the thomsonite so it breaks away without hurting it and after that the rest comes off in the tumbler becuase its soft.
Chuck
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Minnesota Daniel
freely admits to licking rocks
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Member since August 2011
Posts: 891
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Post by Minnesota Daniel on May 23, 2012 22:40:46 GMT -5
The mineral Thomsonite comes in different forms and is found in several places around the world. The rare form you refer to is the eyeball looking variety from Thomsonite Beach, MN and Isle Royal National Park. Somewhere on the UP of Michigan too I think. As I understand it, other much more ordinary looking zeolites can sometimes be Thomsonite, just not the famous eyeball variety.
Thomsonite is harder than basalt, but you still have to very careful chipping it out of the matrix.
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Post by gingerkid on May 24, 2012 22:57:09 GMT -5
The rock with the quarter on it in the center photo looks similar to BC Flowerstone. Doesn't pudding stone come from Canada also? Very nice rocks to find at a local place that makes concrete blocks. Howdy, R2D!!!
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