nursetumbler
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Member since February 2022
Posts: 917
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Post by nursetumbler on May 24, 2022 15:34:30 GMT -5
Found yesterday while rocking
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Post by RickB on May 24, 2022 17:08:25 GMT -5
Pretty coral
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nursetumbler
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Member since February 2022
Posts: 917
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Post by nursetumbler on May 24, 2022 17:58:50 GMT -5
RickBI wish I could get part out to see it 3D. That would be awesome
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Post by vegasjames on May 24, 2022 18:51:30 GMT -5
RickB I wish I could get part out to see it 3D. That would be awesome If the fossil is in limestone you can. I do this often with my fossils, which are silicified but in a limestone matrix. I soak the piece in diluted hydrochloric acid (muriatic acid, pool acid) checking it frequently until it is where I want it. That acid dissolves away the limestone but does not harm the silicified fossil.
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nursetumbler
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Member since February 2022
Posts: 917
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Post by nursetumbler on May 24, 2022 18:53:17 GMT -5
RickB I wish I could get part out to see it 3D. That would be awesome If the fossil is in limestone you can. I do this often with my fossils, which are silicified but in a limestone matrix. I soak the piece in diluted hydrochloric acid (muriatic acid, pool acid) checking it frequently until it is where I want it. That acid dissolves away the limestone but does not harm the silicified fossil. 🤔 hmmmmmmmmmmmm Thank you vegasjames. So it wont hurt the coral?
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Post by vegasjames on May 24, 2022 19:23:42 GMT -5
If the fossil is in limestone you can. I do this often with my fossils, which are silicified but in a limestone matrix. I soak the piece in diluted hydrochloric acid (muriatic acid, pool acid) checking it frequently until it is where I want it. That acid dissolves away the limestone but does not harm the silicified fossil. 🤔 hmmmmmmmmmmmm Thank you vegasjames . So it wont hurt the coral? The coral should be silicified, and therefore the acid would not touch it. You can try a drop of acid on the coral to double check.
Here is an example. These are fossil sponges that were both encased in the same piece of limestone. I soaked them in the dilute HCl removing the first sponge entirely and leaving some limestone attached to the second one.
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nursetumbler
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Member since February 2022
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Post by nursetumbler on May 24, 2022 19:51:54 GMT -5
🤔 hmmmmmmmmmmmm Thank you vegasjames . So it wont hurt the coral? The coral should be silicified, and therefore the acid would not touch it. You can try a drop of acid on the coral to double check.
Here is an example. These are fossil sponges that were both encased in the same piece of limestone. I soaked them in the dilute HCl removing the first sponge entirely and leaving some limestone attached to the second one.
Thats awesome. I will try it
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Deleted
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Post by Deleted on May 25, 2022 14:40:09 GMT -5
Cool find!
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rockbrain
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Member since January 2022
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Post by rockbrain on May 25, 2022 15:13:25 GMT -5
Nice!!!
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Post by rockjunquie on May 25, 2022 16:25:04 GMT -5
Cool!
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Post by rmf on May 25, 2022 20:15:49 GMT -5
nursetumbler The rock vegasjames has is quartz replaced. The coral you have is calcite replaced. The acid will eat it up. Based on the look you found it in MI somewhere between Traverse City and Alpena. So it is replaced by calcite like the petoskey stones. Limit acid use.
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nursetumbler
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Member since February 2022
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Post by nursetumbler on May 25, 2022 21:37:21 GMT -5
nursetumbler The rock vegasjames has is quartz replaced. The coral you have is calcite replaced. The acid will eat it up. Based on the look you found it in MI somewhere between Traverse City and Alpena. So it is replaced by calcite like the petoskey stones. Limit acid use. Thank you but no it was found in the thumb. I'll just leave it the way it is
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nursetumbler
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Member since February 2022
Posts: 917
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Post by nursetumbler on May 25, 2022 21:38:06 GMT -5
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nursetumbler
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Member since February 2022
Posts: 917
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Post by nursetumbler on May 25, 2022 21:38:31 GMT -5
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nursetumbler
Cave Dweller
Member since February 2022
Posts: 917
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Post by nursetumbler on May 25, 2022 21:39:05 GMT -5
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Post by vegasjames on May 26, 2022 2:08:52 GMT -5
nursetumbler The rock vegasjames has is quartz replaced. The coral you have is calcite replaced. The acid will eat it up. Based on the look you found it in MI somewhere between Traverse City and Alpena. So it is replaced by calcite like the petoskey stones. Limit acid use. Coral is calcium carbonate. Calcite is calcium carbonate. So you are saying the calcium carbonate was replaced by calcium carbonate?
Personally, I do not think the fossil coral does not look like calcite. Zoom in, especially in the second photo. You can see what looks like quartz including under the dimples of the coral, which looks like a pale blue silicate.
Petroskey stones are a mix of silica and calcium carbonate.
Even calcites can be subjected to acid treatments though. Look at all glossy calcite on the market for example. That high gloss is not natural. It is acid treated to make it that way.
As I mentioned in my earlier post though the acid needs to be diluted and the stone checked frequently. If concentrated HCl s put on calcite is fizzes and is neutralized almost immediately. So there is no control and creates an uneven effect. By diluting the acid in water this slows the reaction greatly and creates an even effect across the dissolveable part of the stone. Unless I am trying to remove the fossil from the limestone (calcium carbonate), I check the stone starting out about every 1-2 minutes to see how fast the reaction is going. This is increased by increased concentration of acid and slows as the acid is neutralized in the reaction. Therefore, when I am doing relief with things like fossil star coral or crinoids both common around here, I check frequently as I only want relief, not the fossils falling out.
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Post by Son Of Beach on May 26, 2022 14:41:59 GMT -5
Rob over at Michigan Rocks made a short video showing the results of using these methods.
Maybe this will help your decision making process.
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jamesp
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Member since October 2012
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Post by jamesp on May 28, 2022 9:36:57 GMT -5
ashley, the above video may interest you.
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