Pyrite Disease? Oh The Carnage!

[galaxy777]

My hubby and I were hunting for fossils along Choctaw Creek in Grayson Co. Tx. when we came upon several ammonoid's and gastropod's in a small and thin section of sandstone within gray shale/mudstone. I am still very wet behind the ears on formations, but I think that this is part of the Woodbine group; although I could be wrong.

To our horror, they started falling apart when we would expose the fossils. They have this white and yellowish chalky substance all over them that I think is pyrite disease.

I washed off as much of the chalky substance as possible on a couple of pieces, along with what was some amazing detail; but I have let the rest of them alone for now until I knew what would be the best approach to the situation.

Is there any way to save these little beauties, or are they doomed?

[Fitch1979]

_{I think I spot some pyrite on your 2 left pics. The ammonite seems mineralised with iron/pyrite. These would give you the risk of turning into dust when exposed to the air bc the Pyrite would react with oxigin.. The others to the right are less clear to me, they seem to be fossilised in some clay matrix (the stone around the fossil), where the fossilised original pearl layer would have reacted with air. Un top of that it dried out. It's I think quite common to happen. Only thing to do is to let them dry slowly and before moving them or stocking them, soak them in something that penetrates deep in the fossil and hardens the fossil. Paraloid B72 would do the trick too.}

_{http://www.thefossilforum.com/index.php?/topic/38500-keeping-pyrite-in-check/}

_{I do think some extra pics would be helpfull to be sure though}

[Fred]

Take care, the residues of pyrite decay are rather toxic.

[galaxy777]

The sulphuric acid is somewhat alarming considering I haven't been using any respiratory masks to clean the pieces and they were just laying around inside the house.

I think I'll put them outside in the storage building and leave them alone until I get a mask to wear.

[Fitch1979]

The sulpher from the pyrite shouldn't be that bad to leave it outside the house. I hope ;-) I bet you shouldn't worry at all about this few specimens. It's like vinegar: a bit is absolutely harmless untill you take a bath in it

Would you have something around that is used to impregnent old walls? The stuff that hardens the surface so old walls w plaster get stablised and don't powder off anymore? That might do the trick as well...

cheers,d

[MikeD]

While some of that may be pyrite rot, some of that (in particular the red matrix with shell fragments) appears to be the original nacre material of the shells, which sometimes can be found around that area.

[PaleoTerra]

Something I've tried on "pyritized" fossils, and has seemed to work quite well, although be warned it will darken the fossils slightly. I cleaned and rinsed the fossils in distilled water with a pinch of baking soda added to help nuetralize any acid that has already formed, then let them dry in preferably a very warm place for a few days, the warmer and dryer the better. I use my work shop, and in Texas, warm isn't hard to find this time of year! An oven set on the lowest setting will also work well. Then I placed them in a container and sprayed WD40 on them until it pooled a little around the fossils. I left this in my workshop for two days, then took them out of the oil and placed them on a couple folds of paper towels to soak up the access oil which has by now penetrated deeply into the pores and crevices of the fossils. I let them set until they began to look dry again. Then I soaked them in motor oil for another two days and repeated the drying process by placing them on more clean paper towels. After the towels look like they started to saturate with oil from the fossils, I would place them on dry towels. I did this for another three days. There will be virtually no residual smells from the oil after a few days of drying. I have done this to every "pyritized", or should I say "marcasitized" specimen, as most pyrite fossils are actually marcasite psuedomorphs, in my collection and have yet to see even the slightest signs of the dreaded pyrite disease!

As a side note, the amount of H2SO4 formed from decaying fossils is relatively harmless, but is highly corrosive, and can seriously damage most materials left in prolonged contact with fossils that have begun to "rot"...

[Ludwigia]

This link can give you further information on how to deal with pyritized fossils. Just choose your own recipe - there are hundreds of them in the end. I tend to keep it simple by 1.washing 2. drying. 3. coating them in cellulose laquer (zaponlack auf deutsch) 4. repeating the process in 5 years if necessary.

http://www.thefossilforum.com/index.php?/topic/38500-keeping-pyrite-in-check/

If you're wanting to save them for posterity in a museum, then the process is far more complicated. For instance, the earth science faculties at the institutes at Tuebingen and Senckenberg have been researching together for years along with other related faculties within their institutes on how to find solutions to slow down or even stop decay within the mass of old pyritized finds from the lower Jurassic of southern Germany or similarly struck layers.

[AJ Plai]

I tried to make somewhat of a poorman's humidifier using silica gel beads and a custom-made acrylic box with drilled hole to pour the silica gel beads in there and keep them under the hollow base.

It's a very simple and low cost approach but probably not pyrite disease-proof since it doesn't prevent oxidation from occurring - simply to keep the moisture out.

Has anyone tried the method of coating pyrite fossils with mineral oil? I heard it the oil creates layer that can help preventing oxygen making contact with the pyrite but doesn't the oil also creates moisture on the fossil when you do that?

And if this method really does work, what kind of mineral oil do u need to use? Will it change the gold color of the fossils if you apply the oil onto fossils?

Thx.