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Help with possible crab concretions


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I've always been really into fossils and prehistoric stuff but I only recently starting going out and fossil hunting. On a recent trip I found 5 concretions from the lincoln creek formation in washington state. I'm pretty sure only the middle one has something in it but I'm at a complete loss at how to go about cleaning these. I dont have a air scribe and I'm completely content with just seeing some of the crab, if there is one inside any of the concretions, and would love some pointers to go about this. 

 

Also how to preserve them once they are exposed. I've seen people using some chemicals but would love a specific brand to use!

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Edited by Neon
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Well... The most basic way is to hit them with a hammer and hope they split nicely, but they are much nicer prepped how @RJB does them, but like you wrote it requires the right tools

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5 minutes ago, Phevo said:

Well... The most basic way is to hit them with a hammer and hope they split nicely, but they are much nicer prepped how @RJB does them, but like you wrote it requires the right tools

Thats what I've done to a previous concretion I had found but the crab inside of it was cut in half and I would rather avoid a crab waiting 15 million years to get uncovered only to get split in half. I read somewhere that theres a method of freezing and thawing? It sounds interesting and in theory could work but I dont know enough about it to know for sure. Additional information would be great

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20 minutes ago, Neon said:

Thats what I've done to a previous concretion I had found but the crab inside of it was cut in half and I would rather avoid a crab waiting 15 million years to get uncovered only to get split in half. I read somewhere that theres a method of freezing and thawing? It sounds interesting and in theory could work but I dont know enough about it to know for sure. Additional information would be great

As far as I know, the Freeze/Thaw method does not work on these crab concretions. 

That is for Mazon Creek type concrteions.
Mechanical prepping with an air scribe and air abrasion is the best way to prep these.

 

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6 minutes ago, Fossildude19 said:

As far as I know, the Freeze/Thaw method does not work on these crab concretions. 

That is for Mazon Creek type concrteions.
Mechanical prepping with an air scribe and air abrasion is the best way to prep these.

 

Im a broke college student and dont have a lot of cash to throw around right now, is there like a dirt cheap one or possibly a method that doesnt involve those? 

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37 minutes ago, Neon said:

Im a broke college student and dont have a lot of cash to throw around right now, is there like a dirt cheap one or possibly a method that doesnt involve those? 

Not to do it properly.  :(  You could try a Dremel engraver with a specialized tip.  Something like this: 

 

 

999_7602_12.jpg   s-l500.jpg  

 

 

I would hold off, and either wait til you can afford some prepping gear, or afford someone to prep them for you. 

 

These seem a bit small for crab concretions, though.  Maybe @RJB will have some ideas. 

 

 

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as a poor college student, wait a few years til you have the money to buy the tools or pay someone to prep these for.  Air scribes and patience are the only way to prep these things.  

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22 minutes ago, Fossildude19 said:

Not to do it properly.  :(  You could try a Dremel engraver with a specialized tip.  Something like this: 

 

 

999_7602_12.jpg    s-l500.jpg  

 

 

I would hold off, and either wait til you can afford some prepping gear, or afford someone to prep them for you. 

 

These seem a bit small for crab concretions, though.  Maybe @RJB will have some ideas. 

 

 

thanks for the info. Indeed they are quite small and I already highly doubted that any of them have any crabs inside of them but the middle one has a bit of something on the surface thats making me wonder. 

Skype_Picture_2020_11_23T04_04_25_036Z.jpeg

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3 minutes ago, jpc said:

as a poor college student, wait a few years til you have the money to buy the tools or pay someone to prep these for.  Air scribes and patience are the only way to prep these things.  

In it for the long haul then! Thanks for the advice.

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  Hi Neon.   Being dirt poor and trying get the tools needed for prepping do not go hand in hand, so to speak.  What Tim suggested is probably your best bet even though ive never used one of those.   Scraping the concretions with a knife really is not the way to go and you will ruin the look of the natural rock and any crab material that may be all the way to the edge of the rock.   And even if you do get yourself a Dremel you need to determine how the crab is situated and then go on the attack from the 'dorsal' side of the crab and then patience will be your best friend after that.  Well, that and a lot of time.  Good luck

 

RB

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Uncle Siphuncle

To prep a good crab nodule from there properly took me 12 hours with an ME-9100 scribe.

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crabfossilsteve

With those round concretions, I hate to say, but I would just use a chisel and hammer to split them.  With the one showing something, you could take the chisel and hammer and hit the concretion about the area showing something.  You could try scrubbing the oblong concretions really well to see if anything is sticking out of the edges.  If nothing is showing use the chisel and hammer method and hit the concretion about at a 1/3 mark and go all the way around the concretion at the level tapping with the chisel and hammer until it cracks.

 

Personally, with those small concretion it would be a big hit or miss trying to use a dremel to see if there is anything there.  I know the chisel and hammer method can be destructive, but the chisel can help to concentration the blow.

 

Before I started investing in expensive equipment, this is how I used to go about cracking the concretions, especially the round ones.  With the bigger oblong ones its more completed to explain, so good luck.  Perhaps you have access to the area you found the concretions for a repeat trip.  Us crab nuts have all been thru this.

 

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I have busted open a bunch of these. The ones I hit at the shortest diameter  broke the concretions and the crab in a vertical fashion, often cleanly in half.  Others that I broke along one of the not-shortest diameter broke along the top of the  crab where you end up with shell on both pieces of the rock and it is a pain to put them back together. 

 

Or you could bring them to the local hospital with a photo of a crab all prepped out and ask if they would be kind enough  to CT scan them to look for hidden crabs.  If you do trhis, be sure to note which ones have a carb and which direction they are facing.  

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As a possible solution to a cash strapped college student, you do have multiple concretions. Maybe offer up a nodule swap for some prep. There are some new preppers on here that may like the offer. 

 

Mike

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Thanks for all the suggestions! sorry had a big power outage and couldnt get on for a while but it was worth the wait!!! only the one that had that little thing poking out actually had anything after chipping away at the rest. I think I'll talk to my pops and use his dremel to prep this one. And for future reference I might try the bartering method with excess concretions sounds like a fun time :)

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