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How to preserve soft fossil wood?


aplomado

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At my main fossil site, soft fossil driftwood is pretty common, buried in cretaceous mud.  It is full clam borings.  Some of it looks great when first dug up, even with the bark still on it.

 

Unfortunately, as it dries it crumbles to fragments.  I think it is full of pyrite.

 

Does anyone know how to preserve wood like this?

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Do you know something about the diagenesis of your area? In other words, what is the rank of the coal in this formation (lignite - subbituminous - bituminous)?

The rank controls, if the wood is stable or unstable in itself. There are some not too complicated tricks to prevent lignite from crumbling.

2 hours ago, aplomado said:

soft fossil driftwood

Ok, this sounds like lignite (= Xylite, if it is still discernible as wood)!

 

If the wood contains some dispersed pyrite, it gets an order of magnitude more complicated. Does it show some white efflorescence, like in the attached pic (Sliced Upper Cretaceous wood fragment of subbituminous rank and some areas rich in pyrite/marcasite)? There seem to exist very specialized tricks to preserve such material.

Ausbluehung.thumb.jpg.9e32dfcbc1b883dbf53d3b4522a4ad26.jpg

 

However, the easiest way to prevent crumbling upon trying and to prevent pyrite disease is to keep the specimens under water...

 

Franz Bernhard

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Someone told me it was lignite, I am not sure what that means.  I was also told it had a lot of pyrite in it.

 

The wood turns black looks almost glassy when dry.  The black wood looks quite like you posted.  There isn't a huge efflorescence though.


Unfortunately, I'm not sure where my digital camera is now.

 

It degrades badly when dried out.  Could keeping it in a jar of water be all it takes to prevent this?

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Have you tried drying it slowly? Typically, a controlled slow drying will keep fossils from falling apart during the drying process. You could the. Apply Paraloid or the like to preserve it.

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16 hours ago, aplomado said:

Someone told me it was lignite, I am not sure what that means

Its very low-rank coal, moisture content around 30-40%. It tends to crumble upon drying. However:

7 hours ago, Ptychodus04 said:

Have you tried drying it slowly?

This indeed works sometimes with lignite / xylite! I have lignite pieces that got only some cracks upon drying, but did not disintegrate, see below.

 

16 hours ago, aplomado said:

The wood turns black looks almost glassy when dry.

Maybe a somewhat higher rank than lignite, but it doesn´t really matter - it disintegrates...

 

16 hours ago, aplomado said:

There isn't a huge efflorescence though.

A little is enough... 

 

16 hours ago, aplomado said:

Could keeping it in a jar of water be all it takes to prevent this?

Yes, and keep it in the dark. It was stable for > 60 Ma in the ground, so "put it back into the ground": Saturate it with water, don´t let oxygen in, keep it in the dark, and the cooler the better. Not the best way to display a specimen, though... :o.

 

Here are two pieces of lignite, with about 30% weight loss upon drying. The above one is a pure xylite (= wood), with the wood grain still visible.

The lower one is lignite s. str. (finely divided organic matter), containing a piece of more or lees featureless xylite. Both have some cracks, but did not disintegrate.

Lignite_kompr.thumb.jpg.39aa253686aa41bc8504453f46a9d02d.jpgFranz Bernhard

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I wonder if it could be dehydrated with ethanol using a dilution series similar to that used in paraffin embedding and then soak / impregnate with butvar (with ethanol as the solvent) and then dry.

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