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How to take care of this (rusty?) Ammonite?!


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dsturgess

Hey all, so I found this ammonite while on Monmouth Beach, Dorset.

 

It looks rusted, and I've read that they can disintegrate over time but I haven't found a clear guide on what to do to;

 

a) polish and clean the fossil

and 

b) stop it from deteriorating

 

If anyone has any advice that would be amazing! Thanks :)

E9p8vdtXoAQ4nky.jpg

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There are a lot of methods, some very complicated, but here's what I would do.

 

1. Scrub it with soap and water.

2. Dry it slowly in the oven at low temp.

3. If it hasn't fallen apart by now then soak it in a mix of zapon lack and acetone for a few minutes.

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FranzBernhard

Welcome to TFF from Austria.

 

Can not contribute much answering your question, but I am very impressed by your pic. A superb shoot :default_faint:! Thanks for sharing.

Franz Bernhard

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ziggycardon

I recently read on a topic in the dutch fossil forum "Paleontica" that putting the fossil in a sealed jar with some ammonia vapors (make sure the fossil doesn't lie inside the ammonia) might remove some of the pyrite disease.

Should that succeed without crumbling the fossil (and that's a big if) I should coat it in Paraloid B72 to avoid further deterioration. But keep in mind the process probably can't be stopped, just merely delayed.

 

Here is the topic I spoke of, it is in Dutch but with google translate you might be able to make some sense of it should you want to read it.

https://forum.paleontica.org/viewtopic.php?f=2&t=37726

 

I also remember @pachy-pleuro-whatnot-odon has some experience with treating pyrite, he might chime in on this topic.

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pachy-pleuro-whatnot-odon

Hi, and welcome to TFF! You've come to the right place for your questions concerning the treatment of pyrite! But, first of all, I want to express I wholeheartedly agree with @FranzBernhard in that you took an absolutely stunning shot of your specimen! :drool:

 

To be fair, I'm currently in exactly the same situation, as I've just come back from the Normandy coast where I've found a couple of pyritised ammonites, with the best one being in more or less a similar state as yours. I too am not to sure as to how to go about preserving the specimen, as their decay is often unstoppable, but here's what I've done/am doing right now:

 

  1. Since it seems that it's mainly the amount of exposure to sea water/saline spray that causes such pieces to decay (@RuMert), I've started off treatement by a series of freshwater baths to pull the salt out of the specimen.
  2. My specimen had some clay still adhering to it, which I carefully scratched off somewhat after a soak in water. I then put my specimen in an bath of diluted household cleaning vinegar (the one without flavour or scent, so basically regular acetic acid at about 5% strength), which was again followed by a series of baths in freshwater for at least an equal duration as exposure to the acid. This should be sufficient to stop the acid from working on the specimen further.
  3. I've then put the specimen out in the sun to dry, and am doing the same right now. Once the specimen is nicely heated up, I'll put it in a Paraloid B72 solution in order to seal it against outside humidity. The heating of the specimen, either in sun, oven or under a heating lamp serves to drive of water present in the natural air humidity.
  4. Once the specimen stops bubbling in the Paraloid-solution, it can be taken out with pincers, dropped on a piece of cardboard and made to dry (tap the cardboard a couple of times to carefully lift the specimen up in the air, since it may otherwise stick to the cardboard - at least that's my experience). If it does stick, or you pull out a piece of the plastic with your tweezers, you can either simply dump the specimen back in the Paraloid or clean it with some acetone. Since the Paraloid-solution also contains acetone, the effect should be the same, and excess Paraloid can be cleaned up using acetone.

There are various other alternatives to this treatment. One, as @Ludwigia suggested, is to replace the sealant with something like a zapon lack or other glue solution, shellack, etc. (we used to use a glue called Velpon when I was a kid). I've also heard of people storing their pyrite specimens in oil, which should also create an airtight seal, but seems less practical in terms of storage. You can clean the specimen with soap and water, or just lightly brush it with water and a toothbrush before sealing. @Ptychodus04 recommends using an iron rust remover (something like Iron Out, though I haven't been able to find it here) even before that... What I certainly wouldn't do, however, is use a metal brush or polish on the specimen, as this is sure to damage it further.

 

As @ziggycardon suggested, ammonia-vapours can also be used to stop the pyrite-decay process. However, this mainly pertains to pyrite-bloom - fine white and yellow crystals/dust that may appear on your specimen and are what can really destroy your specimen - and not so much to the natural and more stable decay product that is iron rust. That is, the thing about pyrite is that, being an iron compound, it has multiple decay products: it can either obtain a black covering - which seems the most stable outcome and appears to protect the specimen from further decay - turn to iron rust, or start blooming yellow and white/grey. The latter is the most harmful form as it is sulferous and will trigger further decay both in the specimen itself and, by air moisture, in other, nearby specimens.

 

The second catch with the ammonia-method is that it's not easy to obtain ammonia-vapours. For, while household ammonia does contain the type of ammonia meant, it's bound to water in such low quantities that exposure to these vapours is more likely to harm your specimen than to do it any good. And to get true ammonia, your either need to chemically process it yourself, or acquire it at a chemical manufacturer directly (which may require a permit). This YouTube-video goes into the topic of how to acquire concentrated ammonia.

 

It's also possible to buy a special pyrite-stabilizer online. However, for this you need to first obtain what appears to be a rather nasty and dangerous solution and mix it with alcohol. I had a look at this, but chickened out from trying this at home, especially since it only works on specimens affected by pyrite-bloom and doesn't actually stabilize the pyrite too much apart from this.

 

More information, including on various ways of treatment, can be found in this thread:

 

 

 

However, I would simply go for (a variation) of the procedure I first outlined above, then store the specimen in a separate box, ziplock bag or other container, and keep monitoring it...

 

I hope this helps :)

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pachy-pleuro-whatnot-odon

And here are some of my recent finds, following treatment. The two largest specimens at the bottom come from the Oxfordian Marnes de Villers of the Vaches Noires at Houlgate, France, the rest was pulled from the Callovian Marnes de Dives, same location (including the small bivalve at the very top).

 

1067915488_PyriteammonitesVachesNoires.thumb.jpg.13b0b80a172c65e64dd0fe3db48d680c.jpg

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

I hope this helps :)

Wow! That is the best summary of the pyrite preservation discussion we’ve had for about a decade! Well done.

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There are several factors. 1st, no matter what a specimen looks like, there are ones affected and others not at all. It depends on the site, layer, mineralisation, etc. For example, marcasite looks much like pyrite, but reacts differently. In a site of mine hauterivian specimens often develop pyrite disease while kimmeridgian ones do not.

2nd, keeping conditions mean a lot: humidity leads to decay, dry air is a must.

3rd, avoid using water on specimens likely to develop pyrite disease. Practice dry cleaning.

4th, there's no safe method to prevent pyrite decay. Lots of specimens are lost even in museums. Some methods I know of include paraffinization (boiling in paraffin), applying various chemicals, covering with varnish, heating on the stove. I suspect all of them are more like practicing magic. Overall I believe quality of the specimens are more important than what you do to them.

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  • 2 weeks later...

I found this page on preserving meteorites while looking for info on ways to preserve (prevent rust on) my Pallasite slice... Maybe it will help, maybe not:

http://www.meteoritemarket.com/preserv.htm

See also the pdf link near the bottom. I still wonder what is the best thing to do, and maybe it varies depending on the specimen and its observed behavior, as RuMert suggests, so I still have not tried anything and I can't speak from experience.

 

I do want to point out, if it's not obvious: if cleaning with soap and water, thoroughly rinse or soak in clean water afterwards, and if rinsing/soaking in water, I would think that it would need a lot of time to dry, and/or a good amount of heat (as in an oven at low temp) to fully drive all the water out of the deeper cracks/pores, before being coated with anything. I say this because my Pallasite slice, though sealed in a coat of epoxy, developed rust spots on the surface beneath the epoxy after only a year or two in my drawer, and these heaved the epoxy up off the meteorite surface in patches, to the point of cracking the epoxy in a couple places! I can only conclude that there was still some H2O in the meteorite slice when it was coated, maybe as little as humid air in the room this was done in (in China, so that would not surprise me).

Edited by Wrangellian
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pachy-pleuro-whatnot-odon
3 hours ago, Wrangellian said:

I say this because my Pallasite slice, though sealed in a coat of epoxy, developed rust spots on the surface beneath the epoxy after only a year or two in my drawer, and these heaved the epoxy up off the meteorite surface in patches to the point of cracking the epoxy in a couple places! I can only conclude that there was still some H2O in the meteorite slice when it was coated, maybe as little as humid air in the room this was done in (in China, so that would not surprise me).

 

This is in fact one of the main arguments in opposition to sealing specimens, as it hard to guarantee all water has been driven off prior to sealing (the larger the specimen the more difficult to ensure), that the seal is complete, and thus that further decay does it take place. For if it does, the sealant will make it harder to treat and deal with ;)

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Tell me about it. I just went through a big hassle removing the epoxy off my Pallasite slice! So now what do I do with it? Treat it somehow, as per one of these various methods, and if so, which one? Or just try and find a more-or-less airtight container and put it in there with some dessicant and hope for the best? Or just get rid of the thing and not worry anymore? B)  I'd like to coat it in something, as it doesn't look nearly as good now!

I also have a piece of Muonionalusta which was not sealed in anything but was cut and etched, and there was recently a worrying rusty bit that popped off the outer crust. I have both pieces in bags with silica packets currently.

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pachy-pleuro-whatnot-odon
On 9/14/2021 at 10:01 AM, Wrangellian said:

I also have a piece of Muonionalusta which was not sealed in anything but was cut and etched, and there was recently a worrying rusty bit that popped off the outer crust. I have both pieces in bags with silica packets currently.

 

Well, keeping the pieces away from moisture and packed separately from other specimens is a good first and will likely buy you some time to think. It's important to note, however, that the etching process - presumably chemical - may actually be part of what's triggering the current decay if the specimen wasn't rinsed properly afterwards (always a big issue when doing an acid prep on fossils too).

 

On 9/14/2021 at 10:01 AM, Wrangellian said:

So now what do I do with it? Treat it somehow, as per one of these various methods, and if so, which one? Or just try and find a more-or-less airtight container and put it in there with some dessicant and hope for the best? Or just get rid of the thing and not worry anymore? B)  I'd like to coat it in something, as it doesn't look nearly as good now!

 

It's hard to advise on what to do with the pieces, as much depends on value (both monetary and scientific as well as emotional), state, mineral composition, and how much effort you're prepared to go through. I'm not quite sure about how to deal with regular iron rust (if that's even what your specimens are suffering from), but you might try an iron rust remover (such as Iron Out, as suggested by @Ptychodus04 for pyrite treatment), and see if that cleans your specimen up. For pyrite, you could try using the pyrite stabiliser I chickened out of, if you're not afraid of experimenting with chemicals... Simply brushing and washing off the rust and then baking the piece in the oven for a while at low temperature to drive off excess moisture may also work, as may inundation in a solution of baking soda (which I once tried to fight bronze disease a long time ago with some success - but this may only work for bronze). Don't treat both specimens simultaneously, however, as you'll first want to experiment on one specimen before trying the other. Once treated and residual water has been removed, I think you could best seal them again, either in epoxy, or by full inundation in something like Paraloid B72 (which you could make a bit more liquid to penetrate the specimen fully to great depth).

 

In any case, don't throw them out just yet, as even if they seem useless as collection pieces, they may prove useful in doing experiments that will help you when next facing similar issues in the future...

Edited by pachy-pleuro-whatnot-odon
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21 hours ago, pachy-pleuro-whatnot-odon said:

In any case, don't throw them out just yet, as even if they seem useless as collection pieces, they may prove useful in doing experiments that will help you when next facing similar issues in the future...

Thanks for the advice. I'm not about to throw them out.. they're not junk - just the rust spot on the crust of the Muonionalusta (which could be trouble in future), and the Pallasite is a little beat up and rust may reappear on it since it already had some, but they're still meteorite samples. I've also got some ancient Chinese bronze coins that I'm worried about. One of them has developed more of that turquoise-looking crust since I acquired it. :fear: Maybe I should just stick to fossils! (and not pyrite ones)

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pachy-pleuro-whatnot-odon
13 hours ago, Wrangellian said:

Thanks for the advice. I'm not about to throw them out.. they're not junk - just the rust spot on the crust of the Muonionalusta (which could be trouble in future), and the Pallasite is a little beat up and rust may reappear on it since it already had some, but they're still meteorite samples. I've also got some ancient Chinese bronze coins that I'm worried about. One of them has developed more of that turquoise-looking crust since I acquired it. :fear: Maybe I should just stick to fossils! (and not pyrite ones)

 

Hahaha! :default_rofl: Yeah, non-ferric fossils would definitely be a safer bet and less of a worry. Still, nothing is entirely free of decay. And while fossils may look stable for a long time, it's not unheard of that they eventually break down all the same. For one, one can imagine the glue and other materials used in their preparation and restoration chemically breaking down - or remnants of acid (from the prep) proceeding to etch away at the inside of the fossil - for another changes in air moisture and freezing temperatures may still continue the natural erosion process, even if at an unnoticeably slow pace (and I'm not even mentioning salt present inside the fossils here!). UV-exposure is another deadly one, as is the always imminent danger of damage due to handling or simply being on display (I still remember how one of the cats at my parents place broke an antique vase because it simply walked past it and got startled). As such, it's not uncommon for fossils that have been in collections for a long time to be reworked/reprepped.

 

At the core this is an issue all collections deal with, irrespective of material and irrespective of whether the collection concerns art, archaeology, historical documents or biological or geological specimens (including fossils). I've heard stories of ethnographic pieces made out of animal pelts, feathers and finely woven basketry looking good for years and years, until they were finally touched and just crumbled to dust (in fact, I've experienced this happening with plastic bags). Properly maintaining a collection takes a lot of effort, monitoring and constant attention. Of course, there's always limits to what we can do, even in museums. But to maintain a collection as a private individual is not as easy as it may at first seem. Depending on material, you'll need to either hire professional restorers or familiarize yourself with the different techniques (as I did). And while non-pyritic, non-ferric fossils seem a rather easy thing to maintain, a lot of them are, in fact, multimedial pieces - meaning multiple materials are present in a single specimen. This greatly complicates maintenance, as each of these materials may have different tolerances and requirements for preservation. Don't get me wrong, I'm not saying other things are easier to maintain in a collection - I personally also prefer fossils over other parts of my collection - but even fossils are not without their worries or concerns...

 

Unfortunately, I can't really recommend what to do with your meteorite specimens, as I have no experience in this area. I know that flax oil is a good way to protect iron against rust once you've removed any visible rust using a tooth brush. But this procedure will darken your specimen, coat it in oil (moreover, vegetal oil that may attract bacteria), and I have no idea about the long-term effects of it. I did, however, treat a rapier this way about 15 years ago, and the specimen still seems to be in excellent condition.

 

As to the bronze coins: it's important that you do deal with the bronze disease, so that it won't keep eating away at your specimen and eventually completely destroy it. I myself have tried three methods in the past, none with fully satisfactory results. Below is an extract from this page, which provides a bit of an overview of common "household"-treatments:

 

Quote

If left untreated, bronze disease will continue to eat away at the metal to the point of complete destruction of the artifact. However, several steps can be taken to both prevent and treat bronze disease. Among private collectors, there are several popular methods of stalling the effects of bronze disease, though none of these are permanent cures. Initially, the reaction can be stalled by removing the moisture from the piece. This can be done by placing the infected coins or artifacts in the oven on low heat in order to dry them out. Unfortunately, this often causes the surface of the metal to darken irreversibly. Additionally, this is certainly not a permanent solution; just one more especially humid day and the bronze disease will be off and raging again. Another non-permanent fix is soaking the afflicted piece in either distilled water or a solution of sodium carbonate and sodium bicarbonate. Again, this will only halt the reaction until the cuprous chloride comes into contact with moisture in the air.

 

While washing and then drying the specimen in an oven at low temperature does work (place it in a closed container with plenty of silica gel packs around it after taking it from the oven to extract more of the moisture from the specimen itself, rather than have it find an equilibrium with the air humidity of its surroundings), my experience is that it'll remove all patina and will turn any light coloured copper red (due to oxidation). The solution involving sodium equally suffers from undesired side effects, as it too removes all the patina, leaving a roughened/etched out surface where the patine used to be (but you might be able to temper this by diluting the sodium more than I did or shortening the exposure). This procedure is described in a bit more detail here:

 

Quote
  1. With running water and a stiff nylon brush, scrub the entire surface free of "green fuzz", allow to dry.

  2. Use a magnifying light and a sharp needle to remove and open any obvious green spots still visible. With care these will not be obvious later.

  3. Pre-pare a bath of 5 parts baking soda [sodium bi-carbonate] to 8 parts washing soda [sodium carbonate]. You may go by weight or simple dry measurement, i.e. tablespoons full. Store the mix in an air-tight container.

  4. Use de-mineralized or de-chlorinated water for better results.

  5. Mix 2 tablespoon of the soda mix to three cups of water; add coins and heat the mix to boiling, reduce heat for a minimum of 5 minutes. Set aside and soaking to continue for an extended period of time. This should be at least 24 to 36 hours, for thick coins like sestercius allow at least 72 hours. After the initial soak, rinse with clean water and give the coin/s a light scrubbing.

  6. Repeat step 5, twice more.

  7. After the last soak and scrub, dry the coins, and soak in 100% isopropyl alcohol, for about 20 minutes. This will help draw out more water from the coin fabric. Dry thoroughly, and seal with a paste wax, well rubbed into the coin.

  8. It is recommended that all bronze coins be checked periodically, as I have found "clean" coins suddenly break out 2 years after purchase.

While this procedure should not effect a true green patina. It will remove any artificial coloring or re-patination.

Reference: For further reading - the following is where some of the information used in this article was derived:

  1. http://nautarch.tamu.edu/class/anth605/File12.htm

 

Lastly, I believe I also tried rubbing the bronze disease off using chalk. Memory fails me a bit on whether I did or did not actually try this, and this is typically a technique applied to silver (thus, it could've been a silver item affected by bronze disease due to having stood in close proximity to an affected bronze object for a long period of time). But the basic idea is that you use a chalk powder (I used ground up blackboard chalk sticks) mixed with a tiny bit of distilled water to make a paste that you then rub on using a cotton swab. While, in essence, this still rubs off a layer of silver (namely, the oxidized part) in much the same way that the home remedy of a tooth brush with tooth paste does, the chalk is much softer and therefore has a more superficial effect that better protects your silver wear...

 

I hope this helps you somewhat :)

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On 9/14/2021 at 8:01 PM, Wrangellian said:

Tell me about it. I just went through a big hassle removing the epoxy off my Pallasite slice! So now what do I do with it? Treat it somehow, as per one of these various methods, and if so, which one? Or just try and find a more-or-less airtight container and put it in there with some dessicant and hope for the best? Or just get rid of the thing and not worry anymore? B)  I'd like to coat it in something, as it doesn't look nearly as good now!

 

Hey mate, what fall is your pallasite from?

I had 2 slices of Sericho pallasite, I bought them coated in resin. Both started to rust and I was faced with the same dilemma - remove resin, treat, recoat and leave on display, or tuck away in an air tight container, or sell and move on. 
I didn't want to put them in an air tight container (sadly, the best option for longevity), what's the point in having them if you can't see/display them. 

I was put in touch with someone after some enquiring, he told me how to treat the rust and apparently there is a good chance the rust will come back on the Sericho pallasites. Also the resin coating wasn't a great method to protect them.

I sold them both with the resin still on and let someone else tackle the problem.

The money from the pallasite slices went toward a really nice, 73mm long Carcharodontosaurus tooth :D

 

But for a few months, I owned one of the most unique and rare objects on earth! (pallasite meteorites make up less than 5% of all meteorite falls). Also I'd just like to point out how ridiculous the word "stony" is in "stony/iron meteorite". Should be "crystal/iron" or something.
I still have a slice from an iron meteorite, showing the Widmanstatten pattern and a small stony NWA meteorite and would love to get hold of a larger iron slice one day 

 

Sorry it's a bit off topic 

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

I hope this helps you somewhat :)

I've been looking into ways to combat the bronze disease on my Chinese coins.. I have a couple different products and an ultrasonic cleaner for that. I tried them on a couple of those coins a while back and nothing has happened to them since - yet - but I wonder if I should not have done it the way I did, as the green patina is valued by Chinese coin collectors as part of their character, and it turned out that one of those coins was a really rare one and I used the ultrasonic on it which flaked the patina off a couple spots, revealing the metal underneath :DOH:

But, I don't know any of the more careful/professional way to conserve bronze items so I was limited, and felt I had to act fast before the problems progressed. I gather that the regular darker green crust is not generally a problem and can be left alone assuming you don't live in a very humid environment, but the lighter turquoise-colored stuff is the more aggressive type of decay that needs attention - that's what I was dealing with on those two coins and this new one.

And I know what you mean that everything is subject to decay and I've already had problems with a few of my fossils, and like Gareth says - what's the point of having them if you can't display them, or can't protect them from decay? I might eventually give up on certain things and pass them on to the next person (or museum, as the case may be) to deal with.

I would be wary of any sort of organic oil, which might go rancid like olive oil and the like do. I wonder if mineral oil is better in that regard. I acquired a big Hanksite (salt mineral) specimen from another member some years back and he recommended slathering it in mineral oil, which I did, but he said it would require periodic reapplications (and then I left it out in the shed for a month or so along with the rest of my rock/fossil collection because the floor in here was being tiled, and it suffered from the humidity and I got discouraged and haven't been taking very good care of it since).

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12 hours ago, Gareth_ said:

Hey mate, what fall is your pallasite from?

I had 2 slices of Sericho pallasite...

 

Sorry it's a bit off topic 

Yes it is a Sericho. I wonder if you got yours from the same source I did, and I wonder how many other buyers have had the same problem.

I guess a gemstone is called a 'stone' so the olivines still qualify, making it a stony-iron. You might be thinking of a rock, which is technically an amalgamation of different minerals. In that sense, a Pallasite is a rock, too. ;)

Sorry from me also - slightly off topic. But maybe the discussion about treating decay in general helps someone.

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1 hour ago, Wrangellian said:

Yes it is a Sericho. I wonder if you got yours from the same source I did, and I wonder how many other buyers have had the same problem.

I guess a gemstone is called a 'stone' so the olivines still qualify, making it a stony-iron. You might be thinking of a rock, which is technically an amalgamation of different minerals. In that sense, a Pallasite is a rock, too. ;)

Sorry from me also - slightly off topic. But maybe the discussion about treating decay in general helps someone.

Seems like rust is a common problem with the Sericho meteorites which is a shame because they're beautiful things! 
My country's version of online had one guy selling a bunch of them of various sizes and cuts (some a square slice, some a slice of an entire meteorite). He told me he bought them with the resin already on the slices. He sold out of them and got a bunch of very small Campo del Cielo meteorites in, which I didn't get any of. 
Haha yeah I know I'm being facetious, I pick up a stone on the beach and throw it. They're grey/brown and opaque, not greenish/yellow and translucent lol. Haha too true, a rocky/iron meteorite ;). On side shift in topic within this off-topic topic, the TV series Meteorite Men is a good watch :) 

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1 hour ago, Gareth_ said:

Seems like rust is a common problem with the Sericho meteorites which is a shame because they're beautiful things! 
My country's version of online had one guy selling a bunch of them of various sizes and cuts (some a square slice, some a slice of an entire meteorite). He told me he bought them with the resin already on the slices. He sold out of them and got a bunch of very small Campo del Cielo meteorites in, which I didn't get any of. 
Haha yeah I know I'm being facetious, I pick up a stone on the beach and throw it. They're grey/brown and opaque, not greenish/yellow and translucent lol. Haha too true, a rocky/iron meteorite ;). On side shift in topic within this off-topic topic, the TV series Meteorite Men is a good watch :) 

I say the Pallasite as a whole qualifies as a rock, as it contains more than one mineral. The olivines qualify as stones (as in gemstones) and are a mineral. The iron might qualify as a mineral unless it is mixed with nickel. The whole thing is a rock. ^_^

I bet your seller got his from the same source in China. I saw pieces of those descriptions there.

I think I saw Meteorite Men when it was on TV a while back.

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2 hours ago, Wrangellian said:

I say the Pallasite as a whole qualifies as a rock, as it contains more than one mineral. The olivines qualify as stones (as in gemstones) and are a mineral. The iron might qualify as a mineral unless it is mixed with nickel. The whole thing is a rock. ^_^

I bet your seller got his from the same source in China. I saw pieces of those descriptions there.

I think I saw Meteorite Men when it was on TV a while back.

:heartylaugh: All I'll say is pallasites are very, very expensive "rocks"! 

That wouldn't surprise me and I bet they were applying the resin on a raining, humid day and also gave the slice a wash in water before applying the resin. On a serious note, maybe that's why there seems to be a known problem of rust with Sericho pallasites, a lot ended up in the hands of people that didn't handle or care for them properly just to make a quick buck. If so, what a shame that is :(

Yep it's an old TV series and available on youtube, Geoff Notkin has his own channel 

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pachy-pleuro-whatnot-odon
6 hours ago, Wrangellian said:

I've been looking into ways to combat the bronze disease on my Chinese coins.. I have a couple different products and an ultrasonic cleaner for that. I tried them on a couple of those coins a while back and nothing has happened to them since - yet - but I wonder if I should not have done it the way I did, as the green patina is valued by Chinese coin collectors as part of their character, and it turned out that one of those coins was a really rare one and I used the ultrasonic on it which flaked the patina off a couple spots, revealing the metal underneath :DOH:

 

Yeah, I never fully understood this point about patina being so important. Of course it speaks to the character of the coin and its history, but its presence is also to the detriment of the coin itself. I'd think that at one point you either need to reduce or stabilize the bronze disease, or else you're just sitting on a time-bomb of when the coin as a whole will become affected and consumed. Very few private collectors would have the means to properly treat such specimens at home, nor keep them away from moisture to such extent that any bronze disease that has set in will not return with time. As such, I'm glad to hear your experience with the ultrasonic cleaner was such a positive one. Generally, however, I don't think I would recommend the ultrasonic cleaner for historical artefacts, as they may be more fragile than they look and could easily get damaged from the vibrations in the cleaner. In fact, this is the way the device works and why a bit of patina broke off as a result. My understanding is that when properly applied, chemical (or, when possible, electrolyte) treatment is a more secure way to stabilize bronze disease. However, as with pyrite decay, whatever treatment you decide to go for is likely to damage the most heavily affected part of the specimen. That's because the specimen in that area has, in fact, already been destroyed, being converted into the decay product, without any way to revert the process. The other point to keep in mind is that none of the treatments available is a complete solution, and you'll always need to keep on your guard for anything to crop up...

 

7 hours ago, Wrangellian said:

I gather that the regular darker green crust is not generally a problem and can be left alone assuming you don't live in a very humid environment, but the lighter turquoise-colored stuff is the more aggressive type of decay that needs attention - that's what I was dealing with on those two coins and this new one.

 

That's generally correct: the lighter the colour of the decay product, the more aggressive and risky it is. However, as far as I'm aware, it's not true that the lighter coloured bronze disease is by definition more of a problem, as much depends on the exact composition of the bronze alloy (what admixtures have been used). In some cases, light coloured bronze disease can be quite stable. It's presence is therefore not strictly a reason for concern. However, it's spread and growth are...

 

7 hours ago, Wrangellian said:

I might eventually give up on certain things and pass them on to the next person (or museum, as the case may be) to deal with.

 

That might not be a bad idea. I mean, it definitely feels like a load to me too sometimes, to ensure proper case of my collection. The thing about museums, though, is that, apart from them being quite full and your specimens therefore probably never again seeing the light of day - may be not even receiving the care they need - many have strict policies that can make it difficult to donate pieces: they may have ethics board in place for ethnographic and historical artefacts, may require full geological provenance, etc. On the other hand, I also feel bad about passing known problematic pieces on to other collectors, as not only would they be buying the proverbial cat-in-the-bag, but they might be even less well-equipped than I am to deal with the issues posed by a certain specimen. As such, I firmly believe problematic pieces can only be passed on in full disclosure of the problems it presents and a complete history of prior treatment (at least insofar as you're aware of it yourself). But that's just how I feel about these matters - it's a tricky question... :)

 

7 hours ago, Wrangellian said:

I would be wary of any sort of organic oil, which might go rancid like olive oil and the like do. I wonder if mineral oil is better in that regard. I acquired a big Hanksite (salt mineral) specimen from another member some years back and he recommended slathering it in mineral oil, which I did, but he said it would require periodic reapplications (and then I left it out in the shed for a month or so along with the rest of my rock/fossil collection because the floor in here was being tiled, and it suffered from the humidity and I got discouraged and haven't been taking very good care of it since).

 

Generally, I agree with your reservations concerning organic oil. However, flaxseed oil has come recommended to me by various knowledgable people in the antiques trade as a good way to treat iron. In fact, flaxseed seems to react differently to iron than do other vegetable oils, as expressed by this quote (the source is a bit off-topic, but the basic principles are the same):

 

Quote

Vegetable oils and shortening leave cast iron soft and prone to scratching and wear and tear, but flaxseed oil — which is essentially the food-grade equivalent of linseed oil, the drying oil that painters and woodworkers use to create a tough, protective layer on their work — makes cast iron surfaces smooth, hard, and even.

 

As said, I've applied it to a rapier over 15 years ago, and the oil hasn't turned rancid, nor have I observed any adverse effects so far... As to mineral oils, I don't really have any experience with them...

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4 hours ago, Gareth_ said:

:heartylaugh: All I'll say is pallasites are very, very expensive "rocks"! 

That wouldn't surprise me and I bet they were applying the resin on a raining, humid day and also gave the slice a wash in water before applying the resin. On a serious note, maybe that's why there seems to be a known problem of rust with Sericho pallasites, a lot ended up in the hands of people that didn't handle or care for them properly just to make a quick buck. If so, what a shame that is :(

They are expensive... I didn't pay too much for mine but I got the "cat in the bag" as Pachy says above!

I think in China where the meteorite was epoxied, especially southern and coastal, the air is quite humid, much like the Southern/Midwestern states, and that might be all it took to encase a bit of water inside the meteorite/epoxy. Here where I live I never thought the air was too humid, and I still don't think it's as sweaty as Southern China or Southern US,  but then there are some humid days in the Summer when you can feel it, and maybe that's enough to set my collectibles a-rotting.

 

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55 minutes ago, pachy-pleuro-whatnot-odon said:

Yeah, I never fully understood this point about patina being so important. Of course it speaks to the character of the coin and its history, but its presence is also to the detriment of the coin itself. I'd think that at one point you either need to reduce or stabilize the bronze disease, or else you're just sitting on a time-bomb of when the coin as a whole will become affected and consumed. Very few private collectors would have the means to properly treat such specimens at home, nor keep them away from moisture to such extent that any bronze disease that has set in will not return with time. As such, I'm glad to hear your experience with the ultrasonic cleaner was such a positive one. Generally, however, I don't think I would recommend the ultrasonic cleaner for historical artefacts, as they may be more fragile than they look and could easily get damaged from the vibrations in the cleaner. In fact, this is the way the device works and why a bit of patina broke off as a result. My understanding is that when properly applied, chemical (or, when possible, electrolyte) treatment is a more secure way to stabilize bronze disease. However, as with pyrite decay, whatever treatment you decide to go for is likely to damage the most heavily affected part of the specimen. That's because the specimen in that area has, in fact, already been destroyed, being converted into the decay product, without any way to revert the process. The other point to keep in mind is that none of the treatments available is a complete solution, and you'll always need to keep on your guard for anything to crop up...

I don't understand how those coins could have lasted in the wet climate in China for so many centuries (other than those ones that were found in a riverbed, buried in an oxygen-starved environment), and then as soon as I get hold of them, they begin to decay. (Well, not all of them, just a few.) Maybe putting them in plastic 2x2 holders is the problem, for the same reason that sealing meteorite samples is bad, and I should take all my coins out of their holders and figure out some other means of storing them loose without getting their info/labels mixed up... Would even a Riker mount be too enclosed? :Confused05:

The ultrasonic machine often seems too weak to remove the things I want to remove from other things, so it seemed like it would not be a problem with the coins where I only wanted to remove that soft, turquoise-colored stuff and I thought the harder malachite-type stuff was safe - but then a piece of malachite flaked off. Live and learn. I'm not certain that the ones I've treated will be stable for ever and I'll keep any eye on it. The coin that has started to turn powdery blue is an untreated one. I guess I need to treat it similarly, and maybe take them out of the 2x2s.

I know that some of the more encrusted coins may have little actual metal left and I'm not touching those - not with the ultrasonic, anyway. But what to do with them?

 

Anyway I didn't mean to hijack this thread and maybe we should take it to a separate topic if there is more to say...

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53 minutes ago, Wrangellian said:

I don't understand how those coins could have lasted in the wet climate in China for so many centuries (other than those ones that were found in a riverbed, buried in an oxygen-starved environment), and then as soon as I get hold of them, they begin to decay. (Well, not all of them, just a few.) Maybe putting them in plastic 2x2 holders is the problem, for the same reason that sealing meteorite samples is bad, and I should take all my coins out of their holders and figure out some other means of storing them loose without getting their info/labels mixed up... Would even a Riker mount be too enclosed? :Confused05:

 

Well, the thing with most of these decay processes is that it's often fluctuations in the conditions of the ambient environment that can set the process off. Hence, the coins were at one point probably adjusted to a stable, if moist, Chinese environment. But as soon as they were transported out of that environment, they were exposed to changes in air humidity, temperature, and more. This may have been what triggered the very first progression of decay - even if the climate at your location is overall very stable. And once decay sets in, it'll continue, however slowly, irrespective of the conditions in the ambient environment. That's because the decay reaction is self-catalysing, meaning the waste products of an initial reaction can trigger a chain reaction.

 

Unfortunately, I can't really recommend you how to deal with the meteorites or coins much beyond this, as a lot really depends on your local environment and the history of the pieces therein. Personally, I never really put pyrite or bronze objects into enclosed boxes, as I never really saw the reason - and I've been lucky so far. In general, though, enclosing these kinds of specimens in confined space should not be an issue, as you're shielding them against outside changes. The flip-side, however, is that if decay sets in within such a confined space, there's nowhere for decay products to escape/evaporate to, so that it's more likely for them to fuel the already ongoing reaction, making that go faster. Then again, you'll also not need to worry about other pieces being infected, which is more of a risk if you expose bronze objects to the ambient environment...

 

1 hour ago, Wrangellian said:

I know that some of the more encrusted coins may have little actual metal left and I'm not touching those - not with the ultrasonic, anyway. But what to do with them?

 

Unfortunately, I don't know either... I think for those kinds of specimens you'd best find a specialist, although there's a good chance that for these specific items it's already too late...

 

1 hour ago, Wrangellian said:

Anyway I didn't mean to hijack this thread and maybe we should take it to a separate topic if there is more to say...

 

I think that's not really a problem. At least, as I understand TFF rules, it's okay to have topics digress into others, as the outcome may be very interesting in and of itself ;)

In any case, I don't think I've got much more to add to our discussion, unfortunately, because the above is really quite the extent of my knowledge and experience on the topic (which is not to say we can't finish the conversation - I just don't think there's a need to open a new thread any more) :)

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

I think that's not really a problem. At least, as I understand TFF rules, it's okay to have topics digress into others, as the outcome may be very interesting in and of itself ;)

In any case, I don't think I've got much more to add to our discussion, unfortunately, because the above is really quite the extent of my knowledge and experience on the topic (which is not to say we can't finish the conversation - I just don't think there's a need to open a new thread any more) :)

Right.. I'm about as far as I can get too. :s_confused: We'll leave it at that. Thanks for the exchange, it kind of confirmed some things I already knew but it helps!

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