bonsai012345
off to a rocking start
Member since June 2023
Posts: 6
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Post by bonsai012345 on Jun 26, 2023 14:19:45 GMT -5
Hi! New rock hunter here, hoping for some help. I find this everywhere along the western shores of Lake Michigan. I have been searching for Petoskey stones and these keep tricking me, when they're dry, the white part resembles the chalky look of a Petoskey stone. - imgur.com/gallery/81zCgnd - imgur.com/gallery/00H9NOe - imgur.com/gallery/gR0NYSE - imgur.com/gallery/X63RhDk1. Color - photo 2 shows gray/white when dry, photo 1 shows gray/brown when wet. opaque 2. Shapes and Cleavages - photo 3 shows a freshly broken piece. the small fractured piece is wet. 3. Hardness - cannot be scratched with standard nail 4. Weight - Specific Gravity - I don't have a specific measurement but the rock has a dense, cool feeling in hand 5. Acid, Base, or Salt - I have vinegar and salt but didn't understand how to run this test. I am happy to do so with more explanation. 6. Flame Tests - I don't have equipment necessary to run this test The closest ID I've found was in Lake Michigan's Rock Picker Guide (Bruce Mueller): image 12 under the Color Photographs section shows "Cladapora: polished and natural". The rock on the left looks like an ultra polished/more saturated version of what I've found. see photo 4 I'd love feedback on what you think this may be. Thanks so much.
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Post by jasoninsd on Jun 26, 2023 20:23:40 GMT -5
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bonsai012345
off to a rocking start
Member since June 2023
Posts: 6
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Post by bonsai012345 on Jun 27, 2023 13:03:01 GMT -5
Thank you for posting these! I will figure out how to embed images next time. Thank you for the warm welcome. I traveled across SD on 90 last fall. I was humbled at the beauty of the badlands and black hills. SD might be America's best kept secret.
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Post by Starguy on Jun 27, 2023 15:57:01 GMT -5
Welcome from Idaho.
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khara
fully equipped rock polisher
Member since September 2022
Posts: 1,751
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Post by khara on Jun 27, 2023 23:47:22 GMT -5
Welcome. I can’t help either unfortunately. I’m here because I love the look of polished cladopora but unfortunately haven’t gotten my hands on any to work with yet. Keeping my eye out. Yours does not look like the images I’ve come to know as cladopora but that doesn’t mean anything. I also sometimes see it spelled caldopora. Hopefully someone here can chime in with knowledge.
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bonsai012345
off to a rocking start
Member since June 2023
Posts: 6
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Post by bonsai012345 on Jun 28, 2023 12:23:15 GMT -5
Welcome. I can’t help either unfortunately. I’m here because I love the look of polished cladopora but unfortunately haven’t gotten my hands on any to work with yet. Keeping my eye out. Yours does not look like the images I’ve come to know as cladopora but that doesn’t mean anything. I also sometimes see it spelled caldopora. Hopefully someone here can chime in with knowledge. Thanks for this feedback. Polished cladopora is beautiful. I am working on polishing up some of this rock and will let you know how it turns out. I do hope for a better ID if anyone recognizes this!
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LadyBlair
off to a rocking start
Living the rock life
Member since October 2020
Posts: 6
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Post by LadyBlair on Jun 29, 2023 10:37:09 GMT -5
Well, it looks like limestone similar to the color of petoskey stones without obvious fossils. The bands may be another mineral or fossil. Have you looked at the stones under magnification? I'm familiar with limestone beach rocks on the upper north eastern side of Lake Huron. The petoskey's I find are the same color, so you're on the right track. If the stone is placed in vinegar and creates bubbles, it's probably a limestone/calcite mineral. If no bubbles, rule out limestone/calcite. After the vinegar soak, rinse with water, then dunk the stone in a water baking soda bath to neutralize the vinegar acid.
Some fossils in limestone are harder than the metrix mineral (limestone). If the nail was scratched on the fossil area and not the limestone, it might not leave an indentation. Whereas if the nail was scratched on the limestone, it would mark. Dolomite is a possibility, slightly harder than limestone.
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bonsai012345
off to a rocking start
Member since June 2023
Posts: 6
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Post by bonsai012345 on Jun 29, 2023 14:19:19 GMT -5
Hi LadyBlair -- thank you so much for this help. I have some of it tumbling right now so I'll upload magnified pictures in a few days when they have a break. I'll also perform the vinegar test and the scratch test over both patches of color and will report back. I have found this everywhere along the shoreline and it's so distinctly patterned that I had to track down what it was. Still looking for my first Petoskey stone. I am often searching the west side of lake Michigan but I may need to venture east to find one. Thank you for sharing your insight, you're just the person I needed! All the best to you
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michiganpebbler
spending too much on rocks
Member since April 2023
Posts: 344
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Post by michiganpebbler on Jun 29, 2023 14:27:44 GMT -5
Welcome from Michigan!
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bonsai012345
off to a rocking start
Member since June 2023
Posts: 6
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Post by bonsai012345 on Jun 30, 2023 16:42:07 GMT -5
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Post by jasoninsd on Jun 30, 2023 23:09:40 GMT -5
Thank you for posting these! I will figure out how to embed images next time. Thank you for the warm welcome. I traveled across SD on 90 last fall. I was humbled at the beauty of the badlands and black hills. SD might be America's best kept secret. Sorry for the delayed response...been a weird week! You know, I have to say sometimes I take for granted what this area has to offer as far as beauty. I've lived here most of my life...and where I live right now, I can basically see the Black Hills and the Badlands from up at my mailbox! Where I go out and hound most of the time (Railroad Buttes) is basically the "tail end" of the Badlands...
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