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Preparation of fragile crystallized fossils


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rickeclectic

I have several fossils that have crystallized shells. I would like any advice on preparing the fossil without having the crystallized structure disintegrated. See example photo and the crystals structures around the edges of the spiral. Thanks.
.1493191051_fragilecrystallizedfossil.thumb.jpg.c596f3f682f4b81839d60fe382705756.jpg

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I think what you are seeing here is that the crystallized area is the mineralized shell itself, leaving mostly the steinkern in place. It is possible, but incredibly difficult and requiring specialized tools most likely as the calcite of the shell usually adheres more strongly to the surrounding matrix than the steinkern. You can try stabilizing the visible crystal and then very carefully and slowly working at the exterior of the matrix with an air scribe until you get very close to the calcitic shell and then switch to abrasion. 

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I agree with Kane.  This sort of thing is very difficult and slow going.  

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rickeclectic

Thank you for your answers! You have reinforced my worst fears :fear:.  I have found a number of such examples, though the others are almost all bivalvy things.

 

So you don't think that something like Paraloid would seep into the whole crystal matrix to the bottom of it?

 

And if so, could I then use some acid (starting with vinegar) and small hand tools (dental picks etc) to help peel away the non-fossil material?

 

It that will not work, I may be out of luck in the short term.  I don't have an airscribe (maybe Santa Claus will give me one next Xmas :-) so I expect I would have leave these samples as is for now. Unfortunately. If the stabilizer will not penetrate enough and the acid will not help, I will just have to hold onto them till I can find the tools and patience (and luck).

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If you  put any consolidant in there, and it does seep in to the calcite, or whatever the crystals are, it will also bind to the rock so it will be difficult to separate the rock form the crysatl.  Acid will eat the shell (crystals) much faster than it will eat the rock, if it does at all.  And if it eats the rock, it will also eat the steinkern.  

 

If I were to try this, I would practice on the bivalvy things before attacking this one.

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By the way, this appears to be a gastropod.

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Bonehunter

Not sure if this helps, but I use insulin (27g), 30g and 46g needles for conodont work. For the 46g -these are cheap "felting needles" used for sewing. You can get several for less than 10.00. I get mine from Etsy. in hard matrix you'll dull them quickly.  Bone

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