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"how To Preserve Pyritized Fossils" Article


silverphoenix

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Please review my article below and let me know what you think. I'll be submitting it to the HGMS to put in their newsletter. You may reproduce as long as I get some credit and you send me a copy =)

Preserving Pyritized Fossils

Pyritized fossils, such as those from the Del Rio Formation of Waco, Texas, face one common problem, pyrite rot. Pyrite is composed of iron and sulfur, which will rust just like anything else containing iron. There are few fossil horrors worse than collecting an entire frame of beautiful pyritized ammonites and forgetting them in a drawer for a few years, only to rediscover little piles of rust where your prized ammonites used to be.

If you collect pyritized fossils, you have to take some proactive steps to protect your fossils from their two main enemies: oxygen and humidity. There are multiple ways to prevent (or rather slow to a crawl) pyrite rot. But I have been using a method that does not require coatings or alterations to the fossils themselves and that allows you to still easily display them (unlike putting them in jars of mineral oil).

First, dry out your fossils, removing all humidity possible. You can do this by putting your fossils on a cookie sheet or foil in the oven and bake at about 150 for an hour. Do not preheat your oven as you want their temperature to rise slowly. Allow your oven to cool for an hour or two before removing so your fossils do not cool too fast.

Next, you need to seal your fossils. You can protect your fossils from further humidity and oxygen exposure by creating a barrier and by reducing the oxygen and humidity within this new sealed microenvironment. I've found the best way is to use the materials and methods below:

1. Mylar ziplock bags with clear front and sliver back. I use 2.5"x4" but you can use slightly larger or smaller sizes. ($0.06 each or less on Ebay)

2. Impulse Heat Sealing Machine, 8" recommended ($20 or less on Ebay)

3. 50cc Oxygen Absorbers ($0.10 or less on Ebay)

4. 1 gram packets of Sorb It silica gel desiccant ($0.10 or less on Ebay)

To seal your fossils after drying them, simply take them out of the oven, place them in the small mylar bags you want them to be displayed in using nitrile gloves (try not to get your skin oils on them). Put one oxygen absorber and one desiccant bag in each mylar bag and close the top of each bag, trying to press out as much air as possible. I've found it easiest to remove most of the air by inserting a small straw into the bag and zipping the bag up to the straw, then sucking out what air I can while simultaneously pulling the straw out of the bag and pressing the last bit of the ziplock shut.

After you have sealed each mylar bag with its fossil(s), desiccant, and oxygen absorber, place in on the heat sealer as close to the fossil and packets as is practical so you can make as small of a compartment as possible. Close the lever using the palm of your hand over the center of the lever to apply even pressure to get a good seal instead of just using the small knob/handle at the end. I usually use setting 3 on my heat sealer, but yours may vary. I usually close the handle for 3 seconds, open it and allow the bag to rest for 5 seconds, then pull the bag straight up from the heat element. Otherwise, the heated portion of the bag may separate since it is partially melted in the process.

With your newly sealed bags, you can cut off the top or leave as-is. Label the back with an address label including all relevant information to the specimen contained. You can store these bags in a riker frame to display, or catalogue them and put them in a box.

Edited by silverphoenix
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Make sure to hit the informative info button so maybe this will become a sticky :)

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Good plan, Chase, never thought of the heat sealer, plus with the dessicant etc it seems like you've covered all bases with this method. It may not be pretty but if the aim is to preserve, ya gotta do what ya gotta do. I havent thought much about pyrite fossils as I don't have too many to worry about though I do have those few from TX that I think you sent me. Do you have a method of removing the bits of rot that have already built up, or are you getting them sealed before there is any?

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I don't have pictures at the moment. On a rig for the next couple weeks, but I'll try to get pictures when I'm back.

Using this method, Oxygen will not be able to penetrate the mylar and the environment inside should be practically humidity and oxygen free, meaning that there will be no components with which the iron can oxidize and the bacteria that cause "pyrite rot" will not be able to survive.

So far as removing pyrite rot, I know there are rust removers and rust neutralizers on the market, but I have not experimented with those yet--this is mainly to prevent rusting/rotting in the first place. I think I sent those with desiccant at least though (can't remember). I've advanced my methods since then.

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My first attempt at preserving a nice piece of pyritized wood with an acrylic coating ended about two weeks later with a mini explosion that had me diving for the floor.

Nice article and it should be pinned

It's hard to remember why you drained the swamp when your surrounded by alligators.

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Keeping them in oil works, but it's near impossible to display them unless you have some sort of acrylic frame custom made and sealed.

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Thanks gor the input!

It's very close to the method I've chosen ( after much perusing on internet to compare theseveral different methods existing over there )to preserve my pyrite ammos from Provencal gargasian , also in a somewhat lesser extend from Viller .

Interestingly , no need for this for ammos from a local pliensbachian site , which I just clean and store as is ,with no degradation so far .

One difference though , I didn't put the dessicant and oxygen absorber into the ziplock .Not knowing the exact chemical composition , I'm still afraid of some reaction between the absorber and the fossil.

Comparing the fossils of the same age coming from different places , I've also noticed some differencial trends to rot , whatever the initial status at discovery time ( i.e already exposed ,or still embedded in the marls) . Maybe some tiny differences in the composition of the fossil to begin with ?

PS :what about the theory of bacteria being the main culprit for pyrite rot ?

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This is a very interesting process and I can see how it works well to stop the chemical process that breaks down the pyrite. I prefer several applications of very dilute PVA to prevent pyrite decay.

First, I soak the specimens in Iron Out over night. Iron Out is a rust stain remover and it cleans the pyrite well. Then, they get a vigorous scrub with a toothbrush and Simple Green, then rinse with water. Once the specimens are completely dry (I'm going to modify this process in the future to include baking as you describe) I mix an acetone-PVA ratio of 50:1 and apply generous amounts to the fossil waiting 10-15 minutes between applications. The extremely dilute solution allows the plastic to be carried to the center of the fossil. 3-4 applications are all that is required to completely seal small specimens. This process does not significantly alter the appearance of the specimens and has shown to be effective in the prevention of pyrite disease. This also has the added benefit of allowing the fossils to be more easily handled.

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Hi,

I always thought that pyrite decomposed because of the high rate of sulfur that it contains in some deposits. I have ammonites from Deux-Sèvres (France) which never degraed beside 20 years and without particular treatment. Pyrite = Fe S2.

Coco

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

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

Un Greg...

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like Coco I've had marcasite/pyrite fossils break down and was told the liquid that rots the box was sulfuric acid, the sulfur component being the culprit. Even smells of sulfur. Am not sure this would qualify as "rusting". Not sure if there's a better word for chemical decomposition though. Great note!

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I have had both occur on pyrite specimens. The sulfuric acid produces a white powdery substance out of your nice ammonites. The rust is your typical red version. There seems to be a direct correlation between the two types of degradation and the amount of sulfur in the pyrite as the ones that actually rust do not smell of sulfur at all.

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Dang, it seems like every topic these days has been covered already...thank you for posting this though. Similar principal, just no real specifics on where to find the materials and I can't seem to find the products it mentions readily available. This is more meant as an easy, safe, and cost effective solution. Since Water (or rather hydrogen) is a main component of sulfuric acid, I would think this solution would also prevent the decay of pyrite specimens containing high concentrations of sulfur as well since there would be little of nothing for the sulfur to react with.

This also pertains mainly to those ammonites from the site mentioned (Del Rio Fm), which are primarily composed of iron and which do rust.

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I think your method will help protect material that has the typical 'pyrite rot', as seen in a white powdery disintegration, due to the creation of acid from moisture in the air.

I have had some luck with 50/50 Elmers white glue and water applied to a mostly dried specimen in several successive coats. I have stored them in a jar with desiccant bags.

I think I'll try your method with a piece I found recently. I'll post some pics when I get set up.

I was hoping painshill would offer his thoughts on this topic as well.

It's hard to remember why you drained the swamp when your surrounded by alligators.

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  • 2 weeks later...

Squali: I'd be interested to hear more about your exploding fossilized wood. Was that because the pyrite rot continued inside the fossil even though it was sealed?

I have a number of petrified wood pieces from Mazon Creek that are getting the rot. None of them are real significant, but I'd like them not to dissolve away. So, I want to find a somewhat easy solution to at least slow it down.

Somewhere, something incredible is waiting to be known.–Carl Sagan

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Chase,

Your process, and the techniques for implementation, is very clever. They add a couple clubs to the golf bag.

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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I've read a few places the soak in water, let dry, soak in wd-40, let dry, soak in motor oil, let dry method. A Canadian named Reiner Mielke has described it a few places on the internet. Has anyone tried this method?

Edited by Stocksdale

Somewhere, something incredible is waiting to be known.–Carl Sagan

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I am in the middle of a version of that: I just covered them with the motor oil today.

Soak fossils and rinse in distilled water, Dry in low heat oven (140) for 2 hours

While still warm, place in shallow dish (stainless steel or glass) and saturate with WD40 (leave soaking 3 days)

Remove fossils and dry on paper towels in a warm area (Leave 2 days)

Put fossils back in dish and cover with motor oil for 3 days

Remove and dry on paper towels

Place in a dish of unscented talc and brush with soft paint brush to bring out the details.

I was given the warning that the fossils may turn darker. Mine appear darker already with the WD40

Welcome to the forum!

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And both those processes are perfectly compatible with this one if you want ultra protection :)

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That hydro carbon infusion method sounds interesting in that it

is creating a hydrophobic surface. I imagine it is oily to the touch for quite a while?

I have used Elmers glue (polyvinyl acetate) diluted about 40-50% with water.

I have mainly had success on porous specimens like lignite and such.

The exploding piece was coated very well with that stuff you see at the hardware store covering a penny.

The specimen was about 6x4x2 inches and had large clusters of arsenopyrite.

I didn't dry it enough after removing it from the clay. The out gassing caused by

the creation of sulfuric acid inside the rigid coating caused the boom.

It's hard to remember why you drained the swamp when your surrounded by alligators.

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  • 1 year later...

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