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Re: freeing fossils from matrix

> Date:          Sat, 17 Sep 1994 10:17:03 -0400
> Reply-to:      Lightwaves@aol.com
> From:          Lightwaves@aol.com
> To:            Multiple recipients of list 
> Subject:       freeing fossils from matrix

> Does anyone out there know a safe way to release fossils from the 
> matrix holding them?
> I have tried hydrocloric and acetic acid, but in both cases the fossils
> dissolve as well as the limestone, and that's very frustrating.  
> fossils are from the deposits in north Arkansas, and the limestone 
is extra
> hard.  Most attempts at chipping the rock away results in explosive
> fracturing.  
> There are several nice specimens, but they're locked up 'til I  can 
> out a way to free them.
> Tahnx :-)  
> Roger A. Stephenson (lightwaves)
> Morrilton, AR 72110
> 501-354-6439

I agree that the best answer is to use mechanical means.  I don't 
know the material, but I have dealt with some bones in nodules that 
cannot be prepped using acid.  If the matrix is softer than the bone I 
would go for air abbrasive techniques although you sometimes lose 
the outermost thin layer of bone if it is not done carefully.  I have 
used this technique on phosphatised Carboniferous shrimps, and 
have been able to prepare individual blood vessels.  Hot/cold preps 
are sometimes damaging as well.  I have used freeze/thaw on some 
Silurian fish nodules which does seem to work.  On larger boney 
material I would be afraid of cracking through the bone.  I guess it is 
just trial and error.  Experiment on some less crucial material first.

Neil Clark
Curator of Palaeontology
Hunterian Museum
University of Glasgow
email: NCLARK@museum.gla.ac.uk

The first law of Geology is the law of supposition.
(Geological Howlers - ed. WDI Rolfe)