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Conodonts In The Cleveland Black Shale


AverageCollegeStu

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AverageCollegeStu

Hello,

I'm having a little bit of trouble with some prep work with my conodonts. I'm doing some research and I'm trying to figure out a way to dissolve the black shale around the conodonts and not hurt them. This also would have to be practical and timely. Any help with be greatly appreciated.

Thank you

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I would test two soaks, to see which (if either) breaks down the shale: hydrogen peroxide, and strong dishwasher detergent.

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If it's anything like the black shale here, it's next to impossible.

Like trying to get a potato chip out of asphalt without breaking it!

I've yet to find anything that will dissolve it. But the shale I'm working with (Muncie Creek, Eudora, Heebner, etc.) is really quite soft, but brittle, and seems to not be dissolvable.

What I do is get it under a microscope and use a small scalpel (#15) and/or a small sewing needle to carve a square around it. Then I carefully excavate under it until I can pry out the little square with the conodont intact. It isn't always successful, as the conodont still sometimes breaks, but patience and persistence will pay off more often than not. Plus, it's still in matrix, but better than a huge chunk of shale with a ~1mm specimen in it.

I have successfully been able to pick the matrix from 1 complete conodont, but 99.9% of the time the specimen broke when I attempted it.

This may be more tedious and time consuming than you like, but it's the best I've come up with so far.

On the other hand, maybe your shale is different and will dissolve as Auspex suggested.

Good luck!

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Bleach is frequently used to extract conodonts from black shale. The bleach will break down most of the black organic material and then the residue can be screened. It takes several days and frequent changes of bleach.

I should add that the bleach needs to be diluted with water before using.

Edited by Al Dente
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Back in the 70s, I assisted Earl Harris Jr. (faculty, Youngstown State University, Ohio), who was working on the Ohio Shale, Devonian-Mississippian boundary problem using conodonts for his PhD thesis. We attempted many different ways to extract those phosphatic rascals. The problem is that the matrix is also phosphatic, hence a fiasco. Chemical prep is near impossible and the shale is so well indurated that most mechanical preparations (including micro air-abrasives) seemed destined to fail or take a lifetime to achieve. We found, at the time, the only method with some reasonable success was extracting the “bugs” by crushing the shale (forgot the mesh size, but very small... of near conodont size) and running it through a magnetic separator. This resulted in fragmental, though frequently identifiable, conodonts in some numbers from the assemblage. Occasionally, entire specimens were encountered. I don’t know if he ever did complete his thesis. I hope this helps you in some way.

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