bunnyfights
noticing nice landscape pebbles
Member since May 2022
Posts: 88
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Post by bunnyfights on Jun 12, 2022 11:09:03 GMT -5
Greetings all. Here is another interesting find that I could use some help with. Found in Sothern WI in an area that is mostly sedimentary material. This area is subject to glacier deposits as well. Hardness is 6-6.5 Density - 2.85 Does not react to HCL Streak - White to clear Mass - 230 Grams Most pics are in natural light but wet due to the rain. A lot of the material I run into is Quartz so I would guess this. Just don't know if there is a classification for all the craziness with this one. Inside Pic Natural Light Pics
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Post by Peruano on Jun 13, 2022 6:33:20 GMT -5
Nature has been unkind to your stone, but my best guess would be that it is a pegmatite, i.e. an igneous rock with lots of larger than normal crystals of several minerals. The minerals can vary with occurrence but their size and variety are the key factors prompting the generic term "pegmatite". What do you see when you look at it closely without glare?
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Post by rmf on Jun 13, 2022 6:48:22 GMT -5
bunnyfights This is a quartzite conglomerate. You can see the bedding planes going parallel to the blackish lines and finer sediments with the mixed larger grains. It is hard to see in the image if there is mica. Mica would mean the mud that is mixed with the sand and clasts has been converted via metamorphosis. Image 1 & 2 show some larger clasts of quartz and image 5 shows finer sediments with the larger grains. Indicating there was differing water speeds when it was originally deposited.
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bunnyfights
noticing nice landscape pebbles
Member since May 2022
Posts: 88
|
Post by bunnyfights on Jun 13, 2022 12:07:14 GMT -5
Thanks for sharing your knowledge I so appreciate you all taking time to comment. I like how each rock's unique attributes provide insight on what was going on many moons ago. Peruano, I did some research on pegmatite and have found some rocks that match the published examples but did not collect any as I figured it would not polish well. Since I have not started processing\polishing yet, I am not familiar with what rocks polish well outside of Agate, Chert, Jasper, and Quartzite. Is there a rock index somewhere that would provide some insight into how well each rock takes to polishing? Thanks again! Ken...
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Post by rmf on Jun 15, 2022 4:38:30 GMT -5
bunnyfights to answer, " Is there a rock index somewhere that would provide some insight into how well each rock takes to polishing?" The closest thing would be mohs scale of hardness. Make your self a hardness kit composed of your fingernail H=2.5, A copper penny (per 1982) H=3, a good pocket knife H=6, and a piece of quartz, or agate H=7. Typically you will not tumble much that is outside H=6-7. If you do there will be different recipe even with that glass with a H=6 needs special care.
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Post by Peruano on Jun 15, 2022 12:01:36 GMT -5
rmf I knew I couldn't see the surface of the rock well and should have tripped on the fact that not all constituent minerals were large as they should have been in pegmatites. Mia culpa for guessing in the wrong direction.
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Post by rmf on Jun 15, 2022 15:17:45 GMT -5
rmf I knew I couldn't see the surface of the rock well and should have tripped on the fact that not all constituent minerals were large as they should have been in pegmatites. Mia culpa for guessing in the wrong direction. Peruano no worries judging rocks from an image is harder than it looks, we have all missed the mark sometimes. Plus this is a forum it is best guess and not like oops was that your liver I just dropped on the floor...sorry. On the forum we use consensus and if some one does not like our answer they are free to disregard. Buyer beware. In the mean time we all practice our ID skills.
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