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Post by snowmom on Jul 28, 2014 6:30:23 GMT -5
I have found these on 2 beaches near here. They are colored like Kona Dolomite but are hard and the swirling and blistering, etc makes them look like agates. They have withstood the lake and glaciers so are very hard, harder than kona dolomite's 3.5 to 5 mohs rating. I found one of these with pieces of jasper and a tiny bit of silicate matrix like we find in pudding stones clinging to it. I suspect that these were silicated in the same manner as the puddingstone matrix, probably at the same time, if the clue on the piece is any indication. Has anybody else ever run across these? I did a little research on the 'net this morning and it is possible for dolomite to become agatized... I found several explanations for the process and illustrations of other pieces of agatized dolomite but did not find reference to kona dolomite agates. input?
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Post by snowmom on Jul 28, 2014 6:32:38 GMT -5
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Post by Jugglerguy on Jul 28, 2014 7:27:01 GMT -5
It looks sort of like granite to me. I don't think Kona dolomite is found outside of Marquette county.
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Post by deb193redux on Jul 28, 2014 8:37:26 GMT -5
could be quartzite conglomerate. needs cutting to see un-altered surface.
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Post by snowmom on Jul 28, 2014 13:34:03 GMT -5
Rob, not granite, no grain to it, the stuff is all melded together and not individual bits. not pegmatites, either. Remembering that the glaciers came down from the UP and Canada, dragging all sorts of stuff with them when they formed the great lakes; we have gowganda formation, iron band formation and puddingstone (I forget what formation that is) none of which is 'native' to the area, so I don't think its beyond the realm of possibility. Not quartzite at all, no sparkles on any level, no discernible flakes, no conchoids or rectangular fractures on any of the pieces I have found. It is hard,it is waxy and seems microcrystalline. mysterious. yes,deb193redux, I think cutting it would be a good thing. I will be sending some of this stuff to a couple of members here on the boards, so hopefully will get some feedback when they work with it.
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Post by snowmom on Jul 28, 2014 13:38:18 GMT -5
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Post by snowmom on Jul 28, 2014 13:56:10 GMT -5
these are different sides of the same rock. there are about 4 tiny chips of jasper embedded on the surface of this one.
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Post by snowmom on Jul 28, 2014 15:51:02 GMT -5
two more. the whiter of the two shows the round patterns of the fossil algae that the Kona Dolomite is made of, you can see something similar in the very top photo above. The material these are made of is all the same. Staining has occurred to two of the rocks pulled from a lake area where almost all stones are very yellowed. taken as a group is my suggestion that this is Kona in some form more convincing? If I hear from any of the folks I am sending this stuff to, i'll post about it here. thanks
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Post by Peruano on Jul 28, 2014 16:07:15 GMT -5
Deb, Tumbled quartzite can look a lot like these. I know because I keep picking it up thinking its something more interesting. It does polish, but its still quartzite if it started out being quartzite. I"d cut a piece for you. Tom
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Post by snowmom on Jul 28, 2014 17:21:23 GMT -5
Tom, if the package I'm sending you doesn't have a piece of this in it, let me know and i'll send you one of these! Thanks!
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