Using vinegar/acetic acid to reveal small teeth in chalk

[The Amateur Paleontologist]

Hey everyone, hope you're all doing well!

 

From what I've read, small shark/fish teeth can be occasionally encountered by dissolving samples of chalk/limestone in acid. I read Jeppsson et al's 1999 paper on using buffered acetic acid to extract phosphatic fossils (in my case shark teeth), but the method outlined is not that simple and requires access to certain laboratory equipment I don't really have access to right at the moment... All I have is some cheap white vinegar, and some trays and tins

 

I've got some samples of chalk from the Late Cretaceous of Møns Klint, a fossil site in Denmark with relatively diverse fish and shark fauna. Here's the thing - would it be OK to put the samples of chalk in white vinegar (acetic acid)? If it is, I've just got some questions --

1. Should I dilute the vinegar? And if so, by how much?
2. How long should I leave the chalk in the vinegar?

 

Any suggestions and ideas would be much appreciated, I'd love to find some little fish and shark teeth.

 

Christian

[hadrosauridae]

if you have a spare piece of chalk, why not put in to test?  I wouldnt dilute household vinegar, its only 5% strength when new.  What lab equipment do you need to soak a rock in vinegar?

[The Amateur Paleontologist]

8 hours ago, hadrosauridae said:

What lab equipment do you need to soak a rock in vinegar?

 

Quoting one of the papers I read:

Quote

THE NEW STANDARD TECHNIQUE

 

Equipment.

 

1. Plastic vessels with lids (a 10-liter vessel is useful for 0.5 to 2kg samples).
2. Hose [at least 2-3 m long]
3. Colanders, either plastic or stainless steel
4. Hydrometer calibrated from 1.000 to 1.100
5. pH meter and liquids for calibrating it
6. Sieve -- e.g., a nylon sieve with 63μm holes
7. Acetic acid
8. Buffer
9. Water

 

Taken from "The Optimal Acetate Buffered Acetic Acid Technique for Extracting Phosphatic Fossils" by Jeppsson et al. 1999.

Items 4, 5 and 6 would be rather hard for me to get access to right now...

[Ptychodus04]

Leiggi et. al. 1994 calls for 1tsp. Calcium Phosphate for every 1000ml (approx. 4 cups) of 5% formic acid solution as a buffer. White vinegar is 5% acetic acid and acts similarly to formic.

 

You want to make sure you soak in clean water as long as you soak in acid. I typically do a daily rotation, depending on the reactivity of the matrix.

 

 

[Phevo]

With skrivekridt we in Denmark usually use a different method, "glaubersaltmetoden", were you basicly turn the matrix into mush, by creating small crystals that split the rocks (similar to the thaw freeze method, but much faster) which you then sieve afterwards to find the micros. 

 

It has worked fine for me with bryozo chalk aswell

 

[The Amateur Paleontologist]

Thanks for the advice guys.  

 

22 hours ago, Phevo said:

With skrivekridt we in Denmark usually use a different method, "glaubersaltmetoden", were you basicly turn the matrix into mush, by creating small crystals that split the rocks (similar to the thaw freeze method, but much faster) which you then sieve afterwards to find the micros. 

 

It has worked fine for me with bryozo chalk aswell

 

What do I need to make the Glaubersalt Method work?

 

On 18/05/2020 at 10:30 PM, Ptychodus04 said:

Leiggi et. al. 1994 calls for 1tsp. Calcium Phosphate for every 1000ml (approx. 4 cups) of 5% formic acid solution as a buffer. White vinegar is 5% acetic acid and acts similarly to formic.

 

You want to make sure you soak in clean water as long as you soak in acid. I typically do a daily rotation, depending on the reactivity of the matrix.

 

 

Alright, thanks for the information - I'll keep that in mind.