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Would it be possible to prepare this fossil further?


Misha

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Hello everyone!

I recently received this cool fossil from the Devonian in Scotland, it is a Palaeospondylus gunni:

PXL_20210114_211359007.thumb.jpg.ff2d4f4ba5088a5a792eba2b49a97030.jpgPXL_20210114_211447408.thumb.jpg.05aebb1053c7def318ba2a97064a5126.jpg

I have seen fossils of this enigmatic organism prepared in really wonderful ways to expose more of the animal and I was wondering: would this be possible to do here?

I am not exactly sure of the process used on the others, possibly just really fine air abrasion?

The fossil seems to be rather thin against the rock but it isn't completely flat, here are some pictures I took under the digital microscope, hopefully they might show it a bit better.

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Any help would be greatly appreciated,

I am happy to provide more pictures if necessary.

Thank you for your time!

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Very nice indeed! 

I'm a cowardy custard and would leave this well alone. 

Others may be braver and know more. :P

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Life's Good!

Tortoise Friend.

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2 minutes ago, Tidgy's Dad said:

Very nice indeed! 

I'm a cowardy custard and would leave this well alone. 

Others may be braver and know more. :P

I wouldn't touch it either,

I am just wondering if it would be possible to have it professionally prepared in the future.

I don't have the tools, knowledge or experience to be preparing stuff like this

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It depends on a lot of things.  But this would definitely require a good microscope. 

 

How hard is the rock?

Could it be done with acid?  The rock looks like a sandstone, but if it has any limey constituent it might work.  Unless of course the acid also eats the fossil.

How hard is the fossil?

What sorts of tools do you have?

How much experience do you have?

Are you willing to pay a professional?

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29 minutes ago, jpc said:

It depends on a lot of things.  But this would definitely require a good microscope. 

 

How hard is the rock?

Could it be done with acid?  The rock looks like a sandstone, but if it has any limey constituent it might work.  Unless of course the acid also eats the fossil.

How hard is the fossil?

What sorts of tools do you have?

How much experience do you have?

Are you willing to pay a professional?

Sorry that I was not clear, but having it prepared professionally is what I was wondering about.

 

I just tested it on the back and the rock does react to acetic acid.

As for hardness I am not sure how to describe it, I don't have anything to test it on the mohs scale. 

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59 minutes ago, Ludwigia said:

I'll back up what jpc says. It might be possible to improve it, but you have to know what you're doing.

yeah, this is a job for a professional.  Will send PM.  

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From my reading, Palaeospondylus gunni fossils from Scotland are carbonized. So does this make them unable to be prepped????????? Regardless, that is a neat little fishy!!!!! 

 

Mike

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38 minutes ago, minnbuckeye said:

From my reading, Palaeospondylus gunni fossils from Scotland are carbonized. So does this make them unable to be prepped????????? Regardless, that is a neat little fishy!!!!! 

 

Mike

I believe pretty much all of the fish from the Orcadian basin are carbonized, at least they appear to be. I have an Osteolepis from there, it is preserved with very shiny, black scales and fins. These fish are commonly prepared so I don't see why it couldn't be done here.

Also, I have seen these palaeospondylus gunni fossils with some very nice preparation, not sure about what technique was used though.

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From Moy-Thomas 1940: The Devonian fish Palaeospondylus gunni Traquair. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences

 

"Palaeospondylus has been subjected to. two ingenious techniques in the past, both of which added largely to our knowledge of its anatomy. Sollas and Sollas (1903) studied the structure of the head by means of serial sections, and Bulman (1931) by the method of ‘transfer preparations’. In this work the material was only prepared by removing the overlying matrix from the fossil by carefully dissolving it away with hydrofluoric acid, a difficult, but in the majority of cases a very successful technique. Otherwise, little was done to the specimens except to examine them with a low-powered binocular microscope under various liquids, of which xylol gave the best results."

 

 

Dissolving the matrix with hydrofluoric acid is possible but not recommended - hydrofluoric acid is a very, very dangerous stuff. I tried it with my Palaeospondylus and it works. I am a chemist by profession and used to work with dangerous substances but even I learned it the hard way.

Got a very small amount of diluted HF on my fingers - caused a peculiar numbness in my fingertips for two days.

Does Anyone Here Use Hf For Prep? - General Fossil Discussion - The Fossil Forum 

See both Hydrofluoric acid - Wikipedia  and Hydrofluoric acid burn - Wikipedia . Please check the "Health and Safety" part.

 

Edited by oilshale
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Be not ashamed of mistakes and thus make them crimes (Confucius, 551 BC - 479 BC).

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11 hours ago, oilshale said:

From Moy-Thomas 1940: The Devonian fish Palaeospondylus gunni Traquair. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences

 

"Palaeospondylus has been subjected to. two ingenious techniques in the past, both of which added largely to our knowledge of its anatomy. Sollas and Sollas (1903) studied the structure of the head by means of serial sections, and Bulman (1931) by the method of ‘transfer preparations’. In this work the material was only prepared by removing the overlying matrix from the fossil by carefully dissolving it away with hydrofluoric acid, a difficult, but in the majority of cases a very successful technique. Otherwise, little was done to the specimens except to examine them with a low-powered binocular microscope under various liquids, of which xylol gave the best results."

 

 

Dissolving the matrix with hydrofluoric acid is possible but not recommended - hydrofluoric acid is a very, very dangerous stuff. I tried it with my Palaeospondylus and it works. I am a chemist by profession and used to work with dangerous substances but even I learned it the hard way.

Got a very small amount of diluted HF on my fingers - caused a peculiar numbness in my fingertips for two days.

Does Anyone Here Use Hf For Prep? - General Fossil Discussion - The Fossil Forum 

See both Hydrofluoric acid - Wikipedia  and Hydrofluoric acid burn - Wikipedia . Please check the "Health and Safety" part.

 

I’m not massively clued to on acid prep other that aecetic. Im heard to using hd flakes but don’t know wether thats using them separately or mixing them with something else. 

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20 minutes ago, DanJeavs said:

I’m not massively clued to on acid prep other that aecetic. Im heard to using hd flakes but don’t know wether thats using them separately or mixing them with something else. 

HF is a gas or a liquid (boiling point 19.5 °C). I don't know what you mean by HD flakes.

Be not ashamed of mistakes and thus make them crimes (Confucius, 551 BC - 479 BC).

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16 hours ago, oilshale said:

Dissolving the matrix with hydrofluoric acid is possible but not recommended - hydrofluoric acid is a very, very dangerous stuff

I have been thinking about this,

Why is it specifically HF that is used? Is there any reason why other acids wouldn't work? I put a bit of acetic acid on the matrix and it seems to dissolve it.

Thank you for the help

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Hydrochloric acid dissolves limestone, hydrofluoric acid dissolves silica and probably something else. We use the different acids according to the material we want to dissolve, but some minerals disappear in all acids (example calcite)...
 
Coco

----------------------
OUTIL POUR MESURER VOS FOSSILES : ici

Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici
Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici
Mâchoires sélaciennes récentes : ici
Hétérodontiques et sélaciens : ici
Oeufs sélaciens récents : ici
Otolithes de poissons récents ! ici

Un Greg...

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Just now, Coco said:
Hydrochloric acid dissolves limestone, hydrofluoric acid dissolves silica and probably something else. We use the different acids according to the material we want to dissolve, but some minerals disappear in all acids (example calcite)...
 
Coco

Yes, I understand that.

To me, it seems that something like HCl should work here which is why I'm not sure why it has to specifically be HF

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15 minutes ago, Misha said:

Yes, I understand that.

To me, it seems that something like HCl should work here which is why I'm not sure why it has to specifically be HF

Not sure... it would have to have limestone between all those sand grains.  If there is no limey glue (and most sandstones that I am familiar with do not have any) HCl would do nothing.  As coco said, the HF would dissolve the sand (silica).  This would be why one would go to HF.  I imagine if HF has been used on stuff from the same site (as suggested above) it is exactly because of this.   

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30 minutes ago, Misha said:

I have been thinking about this,

Why is it specifically HF that is used? Is there any reason why other acids wouldn't work? I put a bit of acetic acid on the matrix and it seems to dissolve it.

Thank you for the help

Be careful. Though yes it will do thag. It will also dissolve the fossil with it. You need protective barriers to protect. I’d seek proper knowledge or give to a professional

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2 minutes ago, DanJeavs said:

Be careful. Though yes it will do thag. It will also dissolve the fossil with it. You need protective barriers to protect. I’d seek proper knowledge or give to a professional

The fossil is carbonized, are you sure that it would be affected?

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Coaly particles, aka carbonized fossils, will not dissolve in HCl or HF.

But: The CO2 released by dissolving calcite can easily lift off the coaly particles (the fossil!) and the fossil is lost rather quickly*.

I don´t know, if any bubbles are produced by dissolving SiO2 in HF. Well, gaseous SiF4 is produced, but I don´t know the amount of bubbling. @Coco? And coaly particles (the fossil!) can still be lost if "undercut" by the acid.

@Misha, would you like to post or link to some of these prepped fossils? Thanks!

*Had some coalified leaf fossils with thin calcite coating. Tried to remove the calcite coating with very diluted HCl drop-wise. Worked, but some coalified leaf material was also lost due to lifting and undercutting. 
Franz Bernhard

 

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Hi,

 

2 hours ago, FranzBernhard said:

I don´t know, if any bubbles are produced by dissolving SiO2 in HF. Well, gaseous SiF4 is produced, but I don´t know the amount of bubbling. @Coco?
 

I don't know, I never used HF.

 

Coco

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----------------------
OUTIL POUR MESURER VOS FOSSILES : ici

Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici
Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici
Mâchoires sélaciennes récentes : ici
Hétérodontiques et sélaciens : ici
Oeufs sélaciens récents : ici
Otolithes de poissons récents ! ici

Un Greg...

Badges-IPFOTH.jpg.f4a8635cda47a3cc506743a8aabce700.jpg Badges-MOTM.jpg.461001e1a9db5dc29ca1c07a041a1a86.jpg

 

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