How to treat very small pyritized fossils?

[Fishkeeper]

I have a batch of fossils, mostly small gastropods, from the Waco shale pit. Most of them look pyritized to some degree, so I want to treat them to be sure they don't fall apart. Thing is, they're really small- most under 1cm, some as small as 1mm square, and one ammonite that's something like 3mm across. 

 

My original plan was to soak them in Iron Out overnight, wash them with dish soap and a toothbrush, and then coat them in butvar. Is this still the best way to go? Should I soak them for less time since they're so tiny? And any tips on bushing butvar onto such tiny fossils? 

[Fossildude19]

Moisture is the enemy here. 

Here is a Forum Search I did on Pyrite Disease. 

 

Keeping them in an airtight container, with dessicant packs works for some people.

Others choose to use a consolidant to coat their fossils. 

Some members have done experiments of each type of preservation. 

They should show up in the search I posted.

Good luck!

Regards,

[Fishkeeper]

I actually got this method from another member during an info search earlier, I just don't know if it's any different for very tiny fossils like these.

[ynot]

Do a test on one of the lesser pieces to see how it works.

[jkfoam]

Years ago I collected a bunch of the pyritized ammonites from the Lake Waco site.  I studiously reviewed the literature and identified my finds.  They were labeled and stored in polyethylene bags.  Well after several moves around the country and many years I returned to Texas and renewed my interest in fossil collecting.  When I unpacked my Lake Waco material I was disappointed to find that they had all completely disintegrated to a fine gray powder.  I had fallen victim to pyrite disease (or maybe  more properly marcasite disease?).

 

It made me wonder, how could these fossils survive millions of years in a periodically wet/dry lime clay matrix with out disintegrating.  It must be the alkalinity of the limey clay matrix that preserved those fossils.  So, if I ever go back to Lake Waco and collect those small pyritized ammonites  I'm going to store them in polyethylene bags that contains some of that gray limey clay.  Maybe that will work

 

Jim

[ynot]

48 minutes ago, jkfoam said:

Years ago I collected a bunch of the pyritized ammonites from the Lake Waco site.  I studiously reviewed the literature and identified my finds.  They were labeled and stored in polyethylene bags.  Well after several moves around the country and many years I returned to Texas and renewed my interest in fossil collecting.  When I unpacked my Lake Waco material I was disappointed to find that they had all completely disintegrated to a fine gray powder.  I had fallen victim to pyrite disease (or maybe  more properly marcasite disease?).

 

It made me wonder, how could these fossils survive millions of years in a periodically wet/dry lime clay matrix with out disintegrating.  It must be the alkalinity of the limey clay matrix that preserved those fossils.  So, if I ever go back to Lake Waco and collect those small pyritized ammonites  I'm going to store them in polyethylene bags that contains some of that gray limey clay.  Maybe that will work

 

Jim

Once the fossil has been exposed to oxygen there is an ongoing chemical reaction where the oxygen bonds with the iron. This causes the sulfur to debond from the iron. 

Unless the ammonite (iron sulfide) is sealed to prevent this reaction it will eventually fail.

[Ludwigia]

Tony is correct there. It's true, however, that the method that @Fishkeeper wants to use should at least prolong the longevity of particularly "marcatized" fossils. The pyritized ones tend to survive longer. I know that they've been working on a project centered around the Institute in Tuebingen for years, trying to find the ideal solution to the problem, but try as they might, they still keep losing numbers of pyritized Holzmaden slate fossils which are stored in the catacombs there. I'd say you should use the suggested method, since it shouldn't make any difference what size they are. Once the fossil has absorbed as much of the solution as it can, the rest will run off anyway. I'd just suggest placing the fossils in a warm oven for a few minutes before the treatment to rid them of any excess moisture.

[Plax]

an interesting topic. Here is an example of two ammonites from the same site that have different mineralization and hence different survival in my boxes. Was told once that the moisture that is shed in the pyrite disease process is sulfuric acid. I have had boxes rot through and of course labels as you can see from one of the pics.

[hrguy54]

On 12/29/2017 at 7:40 AM, Plax said:

an interesting topic. Here is an example of two ammonites from the same site that have different mineralization and hence different survival in my boxes. Was told once that the moisture that is shed in the pyrite disease process is sulfuric acid. I have had boxes rot through and of course labels as you can see from one of the pics.

No doubt it's sulfuric acid. 

Pyrite is Iron sulfide (Fe S_2).  Sulfuric Acid is H ₂SO ₄,  With some moisture added to pyrite you get all the necessary ingredients.

I have some non-Marcisite pyrite that corrodes ...loses it's luster...so I clean it with Comet cleanser and water. Shine returns and i smell the characteristic odor of sulfur while doing so. Rotten eggs.