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What's covering my plesiosaur vertebra? How to clean


pachy-pleuro-whatnot-odon

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pachy-pleuro-whatnot-odon

Hi all,

I recently decided to buy the below plesiosaur vertebra after having seen it for a long, long time. It dates to the Callovian of the Oxford Clay and was found at Peterborough. I suspect it may be attributed to Muraenosaurus leedsi, as it comes from a cryptoclidid plesiosaur, but is both larger and more elongate that the typical Oxford Clay Cryptoclidus vertebrae I'm familiar with.

 

60270f6658234_MuraenosaurusleedsivertebraOxfordClayPeterborough01.thumb.jpg.4e42d827d1ad5c86eb9adb2c9a515bd4.jpg60270f7744be3_MuraenosaurusleedsivertebraOxfordClayPeterborough02.thumb.jpg.7565c1f1da89d2c78ccf8038a5cbe523.jpg60270f79015cb_MuraenosaurusleedsivertebraOxfordClayPeterborough03.thumb.jpg.02bbaac893a16951bba885a665793824.jpg

 

Supposedly coming from an old collection, it has a blackened exterior that doesn't cover the entire piece, with the more common buff colour visible underneath. As such, I expected the dark colouring to be simple dirt or may be some kind of consolidate that could be removed using acetone to leave a nice and clean looking vertebra in its place. However, since having tried acetone cleaning, the dark colour doesn't come off - suggesting that it isn't surface dirt and any consolidate, if present, is not soluble in acetone.

 

I've also noticed that the black colour doesn't spread equally across the vertebra, which is most noticeable towards the top on the front face (first image) where one half of the vertebra is buff, the other black, with a hard separation in between. As this mottled pattern can be seen in other places on the vertebra as well, I thought that, may be, the vertebra might have been in a fire and have become covered in soot. I find additional support in the latter hypothesis in very brittle pieces of bone in one or two spots, with a charcoal-like grainy texture. Lastly, then, I've spotted a tiny edge of yellow staining/infill in an area where the vascular structure of the bone is exposed, with some white infill in an area adjacent - which I've now started worrying might be pyrite.

 

My questions to you are:

  • Origin of the blackening:
  1. Does the black clouding of the vertebra look like natural preservation?
  2. Related to the above: could the black clouding be due to pyrite decay?
  3. In contrast: could exposure to fire cause the clouding pattern seen on the vertebra?
  4. What consolidate might have been used to result in such colour patterning?
  • Cleaning:
  1. Is there a way to remove soot from a fossil? Has anyone tried?
  2. Other than removal by acetone, what other ways might I try to remove an old, darkened consolidate?
  3. In case of decayed pyrite, I don't think there's anyway to clean the surface, other than, may be, through careful sandblasting, is there?
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pachy-pleuro-whatnot-odon
9 hours ago, LabRatKing said:

Leave it as is, please.

What's your reasoning behind this, if I may ask? Is it preservation of original collection history, history of the object (in case it came into contact with fire), risk to integrity of the object, or because any cleaning will be too invasive. I'm not saying I don't agree or am not considering this course of action, but I'd just want to hear the argument. I mean, I don't think cleaning an object - or, in some cases, even (partially) redoing a preparation - is that uncommon... Just would like to know why this course of action would be disadvised in this instance.

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It wouldn't surprise me if the "black clouding" is pyrite or limonite, which would point to decay. As far as I know, it is not uncommon that finds from this section have pyrite deposits. You could try to remove some of it with careful abrading, but I don't think that it would make all that much difference and may even damage the bone underneath.

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pachy-pleuro-whatnot-odon
6 minutes ago, Ludwigia said:

It wouldn't surprise me if the "black clouding" is pyrite or limonite, which would point to decay. As far as I know, it is not uncommon that finds from this section have pyrite deposits. You could try to remove some of it with careful abrading, but I don't think that it would make all that much difference and may even damage the bone underneath.

Thanks! I was afraid of that, once I spotted the thin strip of yellow and grayish-white inclusions (bloom) in one section of the exposed cancelous bone :fear:

 

I remember some of my finds from Lyme Regis and Isle of Wight having turned black with time, ending up stable,  but this always the entire fossil, rather than parts of it. This is, in fact,  the first time I've seen pyrite covering only part of a fossil... Anyway, it's good to know pyrite is an issue for fossils from this deposit, as I can now deal with it accordingly.

 

Assuming that it is indeed pyrite or limonite, I think you're right in that any mechanical cleaning would not work to the benefit of the fossil. I guess I'll just have to see how stable the decay product is, as to how much it might put the rest of my collection at risk.

 

Thanks again!

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pachy-pleuro-whatnot-odon

Just for clarity, when I'm talking about the area with suspected pyrite bloom, I'm referring to the strip at the bottom of the vertebra as pictured below:

 

20210214_001310_resize_53.thumb.jpg.59f53c1724362626d9db50e64941d7a0.jpg

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Ptychodus04

I also think it is caused by the presence of pyrite. Pyrite can invade portions of a fossil, or replace the fossil completely. Partial invasion is very common on vertebrate material.

 

The occurrence of decay indicates that a remediation is needed for long term stability of the specimen. Here’s the process I use for treating pyrite decay (it can be found in other topics but those discussions are pretty old):

 

1. Mix approximately 1 cup of Iron Out crystals with 1 gallon hot water. Iron Out is a rust/iron remover that is commonly found in hardware stores. 

2. Soak specimen overnight.

3. Scrub specimen with liquid dish soap and a toothbrush (the specimen will be covered in black residue where pyrite is present).

4. Rinse under warm water and continue to scrub with soap until specimen is clean.

5. Towel dry.

6. Dry in oven on low heat for several hours.

7. Procure some Paraloid B72 and mix 1 part plastic with 50 parts acetone.

8. Submerge specimen in solution until bubbles stop coming out.

9. Allow to dry on a cardboard flat in a well ventilated area.

 

Normally, it is bad to get dry vertebrate fossils wet but in this case, leaving it alone is worse! This process will stop the decay and seal the specimen so it doesn’t start back up again. I have specimens showing decay that I treated this way that have been stable for over a decade since.

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pachy-pleuro-whatnot-odon

Thanks for the detailed advise, @Ptychodus04, and the confirmation of the suspected pyrite-condition!

 

Now I'm not quite sure what to do... I don't quite like the idea of keeping a pyrite-affected fossil within close proximity of the rest of my collection, but have also experienced blackened pyrite oxide - either sealed or unsealed - be vary stable over a period of decades, without much intervention to start with. If this piece really does come from an old collection, might it not be stable by now and the above procedure exactly risk triggering further decay? Not even mentioning the various opinions as to whether sealing pyrite-affected fossils is a good or a bad idea (although, the way you recommend it, I guess an air-tight seal would be guaranteed). Isn't it so that the black pyrite-oxide is the stable oxidation-product?

 

And what about Pyrite-stabilizer (from the oldest geological warehouse in the world; not sure if I'd be allowed to mention them here by name, although there's only one place I know of that sells this product)? Or the use of ammonia fumes to stabilise pyrite-bloom? Does anyone here have experience with either of these methods?

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pachy-pleuro-whatnot-odon

Some more information on the Pyrite-stabilizer (ethanolaminthioglycollat) and ammonia-procedures has been described on this forum here:

 

 

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Hi, doesn’t look as bad as you think it does. It just looks like more matrix needs removing thats all. Not sure on peterberough quarry specimens but if pyrite hasn’t been exposed to sea water it should be fine from Decay, dorset material tends to be the worse as far as the uk goes.  Happy to reply to any messages about the way to go cleaning it up.

Dan

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Ptychodus04

I have several Oxford Clay specimens from Peterborough and the pyrite situation is variable. Sometimes, they have been stable, others have decayed badly. So, I treat anything that appears to have pyrite rather than take the chance of having it fall apart.

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pachy-pleuro-whatnot-odon
On 2/18/2021 at 1:14 AM, DanJeavs said:

Hi, doesn’t look as bad as you think it does. It just looks like more matrix needs removing thats all.

Hi Dan,

 

Actually, the matrix for this particular bone appears to be light gray (as I've come to expect from other Oxford Clay material as well), not black. You can spot patches of this matrix in the various foramina dorsal and ventral to the vertebra. So I don't think it's matrix adhering to the bone. Moreover, there's a part of the vertebra where the cancelous, or spongy, bone is exposed. And that too has blackened...

 

On 2/18/2021 at 1:14 AM, DanJeavs said:

Not sure on peterberough quarry specimens but if pyrite hasn’t been exposed to sea water it should be fine from Decay, dorset material tends to be the worse as far as the uk goes.

Hadn't heard of this before. But if true, this might explain why some of my pyritized fossils from Dorset and IoW remained good through the decades: they may simply not have been exposed to the sea long enough before they were found.

 

On 2/18/2021 at 3:30 AM, Ptychodus04 said:

I have several Oxford Clay specimens from Peterborough and the pyrite situation is variable. Sometimes, they have been stable, others have decayed badly. So, I treat anything that appears to have pyrite rather than take the chance of having it fall apart.

Yeah, with the nature of the collection I've now built, I'm also much more inclined towards precaution. Just need to figure out what exactly that means, though. I've kind of set my mind on the pyrite-stabilizer right now, though, as the procedure seems less laborious (i.e., less steps for things to go wrong at), and there's no water involved. Also, this procedure, apparently, should be as effective as ammonia-treatment, which I have heard good things about...

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Ptychodus04
2 hours ago, pachy-pleuro-whatnot-odon said:

 

Yeah, with the nature of the collection I've now built, I'm also much more inclined towards precaution. Just need to figure out what exactly that means, though. I've kind of set my mind on the pyrite-stabilizer right now, though, as the procedure seems less laborious (i.e., less steps for things to go wrong at), and there's no water involved. Also, this procedure, apparently, should be as effective as ammonia-treatment, which I have heard good things about...

Good luck. Post results and process pics so we can bask in the glory of well stabilized pyrite. :thumbsu:

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3 hours ago, pachy-pleuro-whatnot-odon said:

they may simply not have been exposed to the sea long enough

That's a common idea, but most of the bones in my possession had to be exposed to water (fresh) and rain but survived for decades, IMHO more important is to keep them in dry place with low humidity

 

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pachy-pleuro-whatnot-odon
1 hour ago, Ptychodus04 said:

Good luck. Post results and process pics so we can bask in the glory of well stabilized pyrite. :thumbsu:

Will do ;) And thanks for the help so far!

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pachy-pleuro-whatnot-odon
32 minutes ago, RuMert said:

That's a common idea, but most of the bones in my possession had to be exposed to water (fresh) and rain but survived for decades, IMHO more important is to keep them in dry place with low humidity

 

I don't think I quite follow what you're saying here: on the one hand I read to keep at low relative humidity, on the other the fresh water and rain seem to imply this doesn't matter much...

 

This latter is also my impression, to be honest: that as with the preservation of salt-affected pieces, what matters is a consistent relative humidity, rather than the actual degree of humidity. This is because, at least as concerns salt in a specimen, it's the pull of continuous drying and remoisturizing that pulls the salt to the surface and that prevents a natural equilibrium from being reached. With pyrite decay, I think it's exactly this blackened outer layer that I think I've once read about being the stable rusty form. And as with all other rusts, this would then protect the specimen against further decay... 

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I mean people think a specimen exposed to water is already lost, to the extent they wash it only with spirit or acetone (tried it and it feels awful). But in fact most of the stuff I found had been in water for a long time (often in river) and nothing has happened to them since

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pachy-pleuro-whatnot-odon
41 minutes ago, RuMert said:

I mean people think a specimen exposed to water is already lost, to the extent they wash it only with spirit or acetone (tried it and it feels awful). But in fact most of the stuff I found had been in water for a long time (often in river) and nothing has happened to them since

Hmmm, never even considered desalination using alcohol or acetone only... What do you mean by feeling awful? Might be pertinent for me here as well, seeing as following treatment with the pyrite-stabilizer, it's recommended to wash the piece with alcohol.

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Try it and see for yourself:) My thoughts about pyrite: 1. keeping in dry conditions is the most important 2. heavily pyritized specimens develop disease depending on provenance, on my Volga material - Haupterivian specimens are highly susceptible while Kimmeridgian ones are not (same location, both pyritized) 3. There exist dozens of conservation techniques and none is proved to be actually working (for example, parafinization is popular in Russia) 4. sick specimen can infect the others 5. common specimens are not worth the trouble beyond basic means (dry, spaced from others, maybe lacquered, etc), this includes verts

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will stevenson

From what I understand the main cause of pyrite decay is fluctuating humidity and temperature so keeping in them in an air conditioned room is best, if you don’t have access to that, like me, I put them in cool places out of the sun in boxes with those silica packets, seems to mostly work for me but there have been some issues

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pachy-pleuro-whatnot-odon
4 hours ago, will stevenson said:

From what I understand the main cause of pyrite decay is fluctuating humidity and temperature so keeping in them in an air conditioned room is best, if you don’t have access to that, like me, I put them in cool places out of the sun in boxes with those silica packets, seems to mostly work for me but there have been some issues

Exactly, that's what I thought as well. Some of the pyrite pieces I have, have survived decades in a relative humidity of about 60%. Not particularly low, but it has always been stable, both in terms of humidity and temperature...

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pachy-pleuro-whatnot-odon

So, I may have found out why the use of pyrite-stabilizer is so limited - at least amongst collectors: it's almost impossible to get the good quality, pure and high percentage alcohol needed (or, at least, that I think I need) to submerse such a large specimen as this vertebra. I've written both the vertebra's original vendor for some more information on its collection history for hopefully some more insight into how stable the fossil is, as well as the company from which I bought the pyrite-stabilizer (which has still not arrived, by the way) to see if they know whether I can get away with using denatured alcohol (as this would make things a lot easier). But buying non-denatured high percentage alcohol here in France seems to be impossible for private individuals, outside countries often don't ship, and - in any case - non-denatured alcohol for private use is crazily taxed...

 

Will let you guys know as I figure this out. But boy, is this giving me headaches already. And not of the good kind :oO:

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LabRatKing

Which alcohol? Ethanol is readily available to consumers @95-98%. And with a bit of searching you can choose which denaturant- though an MEK/Methanol denatured at that concentration is easy to get as it is sold as backpacking stove fuel.

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pachy-pleuro-whatnot-odon
2 minutes ago, LabRatKing said:

Which alcohol? Ethanol is readily available to consumers @95-98%. And with a bit of searching you can choose which denaturant- though an MEK/Methanol denatured at that concentration is easy to get as it is sold as backpacking stove fuel.

 

True, ethanol at 90+% is easy enough to find. But over here in Europe a colourant is often added, making it more difficult to find a suitable type. Also, I did find MEK/Methanol denatured ethanol. However, I'm not sure what effect these additives would have on the chemical reaction taking place, or whether they'd leave an oily film. That is, Methyl Ethyl Ketone is also known as butanone, which, being an organic compound, to me suggests something along the lines of petrol or another oily compound. I might be wrong in this, though. Hence my need for additional information...

 

In any case, (bio) ethanol solution (ethyl alcohol, solution)> 99,8% Vol, denatured with 1% of MEK and 10ppm benzoate denatorium is quite readily available on the French variant of the online warehouse that sounds like a South American tropical forest. You think this would work for my purposes?

 

Actually, I already bought three bottles of 90% combustible alcohol "for cleaning and burning" today - without colourant. But since it doesn't state what it's been denatured with (and this was before I had even researched denaturing), I'm not sure whether to use it.

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LabRatKing
35 minutes ago, pachy-pleuro-whatnot-odon said:

 

True, ethanol at 90+% is easy enough to find. But over here in Europe a colourant is often added, making it more difficult to find a suitable type. Also, I did find MEK/Methanol denatured ethanol. However, I'm not sure what effect these additives would have on the chemical reaction taking place, or whether they'd leave an oily film. That is, Methyl Ethyl Ketone is also known as butanone, which, being an organic compound, to me suggests something along the lines of petrol or another oily compound. I might be wrong in this, though. Hence my need for additional information...

 

In any case, (bio) ethanol solution (ethyl alcohol, solution)> 99,8% Vol, denatured with 1% of MEK and 10ppm benzoate denatorium is quite readily available on the French variant of the online warehouse that sounds like a South American tropical forest. You think this would work for my purposes?

 

Actually, I already bought three bottles of 90% combustible alcohol "for cleaning and burning" today - without colourant. But since it doesn't state what it's been denatured with (and this was before I had even researched denaturing), I'm not sure whether to use it.

Distill it!

 

or try a high proof grain drinking alcohol! Over here we have “Everclear” which most labs keep on hand for tricky reactions.

 

we use the MEK/ Methanol denatured in the labs daily. To date it has not interfered with any reactions.

only exception is what we use in the HPLC, but that’s not an issue here.

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