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Upper Windom - Middle Devonian


DevonianDigger

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Not sure about this one. When I've been finding super fragile hash I've been bringing it home and soaking it in my specialized concoction. It's been really cool to see what types of micro fossils are hiding in the matrix. This last time I found something curious that I have yet to see. I'm hoping someone here can take one look at it and say, 'boom, that's a ________.'

 

It's ~1cm long and has a very neat hexagonal base. It was associated with a mass of crinoids and brachiopods. (Entire yield can be seen drying in the 2nd photo.)

 

 

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Jay A. Wollin

Lead Fossil Educator - Penn Dixie Fossil Park and Nature Reserve

Hamburg, New York, USA

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The hexagonal base is leaning me toward large crinoid radial?

 

EDIT: never mind, I was taking the description from text, after looking at images of them, I retract my guess.

 

ANOTHER EDIT: It's looking like crinoid spine. Possibly anal spine? Crown spine? Not sure. Still would like some more knowledgeable sources of crinoid info to weigh in. 

Jay A. Wollin

Lead Fossil Educator - Penn Dixie Fossil Park and Nature Reserve

Hamburg, New York, USA

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Definitely a spine from a crinoid. Probably from the calyx.

-Dave

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Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPhee

If I'm going to drive safely, I can't do geology. - John McPhee

Check out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/

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+1 on crinoid. That's a really neat find! I can see why the peculiar shape might throw you. A concoction, you say? Dish on your secret sauce for freeing fossils from the matrix!

...How to Philosophize with a Hammer

 

 

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Yes, I would be interested in your recipe for breakdown of matrix as well, Jay. 

Regards,

 

    Tim    -  VETERAN SHALE SPLITTER

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"In every walk with nature one receives far more than he seeks."

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I may have built this one up a bit too much, lol. I also expect there to be some amount of controversy here.

 

I basically just make a batch of peracetic acid by combining acetic acid and hydrogen peroxide. I use approximately 3 parts acetic acid (white vinegar) with 1 part of hydrogen peroxide. *You should do this with proper ventilation. We're not dealing with high concentrations or volumes, but despite common belief, intimate relationships with chemical reactions do not typically result in super powers. Don't light it on fire and DO NOT feed it after midnight.

 

***It's really important to note here that I am going to try and explain this to the best of my understanding. I am NOT a chemist and I may not be correct. This is just what I've pieced together, and if I'm wrong and someone can correct me, PLEASE don't hesitate.***

 

Because we are presumably using over-the-counter hydrogen peroxide, there will be a water content which will cause the solution to reach an equilibrium of water, acetic acid, peracetic acid and hydrogen peroxide as the chemical trade off reactions. The acetic acid digests the calcium carbonate into carbon dioxide and calcium ions. (This is also good for limestone.) The hydrogen peroxide reaction is explained best in this excerpt that I came across:

 

In the 1947 issue of :'94.-98. Jahresbericht der Naturhistorischen Gesellschaft zu Hannover fuer die Jahre i 942/43 - ! 946/4T', Wemer Wick described the use of hydrogen peroxide (H202) for the disintegration of shale and shaly rocks. This is a relatively inexpensive method and does not require special equipment or trained technicians. The method is based on the unstableness of hydrogen peroxide and its decomposition to H20 and 02. The alkali compounds in the shale act as catalysts accelerating the liberation of O2 from H202. This exothermal reaction supplies sufficient heat to speed up the decomposition without requiring outside energy. The liberation of 02 takes place with rapid successions of minute explosions. These break up the shale facilitating further penetration with H202 and decomposition until all the shale is disintegrated. Although H202 is a weak acid, it is known from experience that it will not harm calcareous microfossils. (from 'The Exploration Desk' Use Of Hydrogen Peroxide in the Disintegration of Shales published by Canadian Gulf Oil Co., Calgary, Alberta) [reprinted: Journal of the Alberta Society of Petroleum Geologists Vol. 3 (1955), No. 11. (December), Pages 206-206]

 

I use old Marie Callender microwave dinner bowls, (because they come with what is basically a strainer in them as well.) I put the matrix in the 'strainer' and submerge the rock in the solution. 

 

As soon as the matrix contacted by the solution it will start to react aggressively with the acid and bubble. (I'm affectionately calling this process 'low-pressure acid fracking', lol.)

 

For the first few hours I check it every hour or so and agitate the sample to encourage the sloughing of the dissolved material while also taking a soft toothbrush to the surface of larger samples to encourage the breakup of the the thicker layers of matrix that forms directly on the fossils (especially on brachiopods.) I also use a tweezer to remove any fossils which have already broken free and are clear of excessive matrix.

 

 Usually by morning, I will have a clear solution with a thick sediment at the bottom. I use the strainer to then rinse the remaining large material in cold water to neutralize the reaction and break up the remaining chunks with a tweezer. (There are often chunks which have not broken up where the material is more compact and has less striation. Especially getting into the dark grey shales.) Depending on what the potential is for the remaining pieces they are either discarded, worked manually or given a second bath.

 

I then spread everything out on paper towels to dry for a few hours, (ESPECIALLY the fine sediment that fell through the strainer, that's where all the weird stuff ends up.)

 

Garnish with seasonal greens and serve. Sorry, wrong post.

 

From there, it's just a question of taking a tweezer and removing the fine fossils from the sediment. Fossils I was originally concerned would be severely damaged, if not completely dissolved in the solution have been recovered with exceptional detail using this process. I do not yet have a means to photograph such tiny fossils, (but I am getting a stereo binocular microscope next week and will try to update accordingly.)

 

The most impressive fossils I've collected this way have been crinoid columnal sections up to 7mm long with diameters of less than 1mm. Something I could have never manually excavated intact.

 

I have used this process on a lot of sedimentary material from Penn Dixie so far with great results, but this is an ongoing experiment so please be careful with your own specimens, (I specifically have been collecting material for this series of tests all summer.) Here are my bullet point notes so far:

 

  • Be careful with bivalve specimens as the matrix between the valves with likely also be broken apart, sometimes catastrophically. (Sometimes you get two awesomely clean valves that can be positioned back together for nice effect. This is amazing if you're trying to study the internal details of the shell, but is against the preferred standard of leaving matrix for context or display.
  • Brachiopods are particularly sensitive to the bleaching effect of the peroxide. It makes them take the appearance of having just been found on a beach, which is highly attractive, but not authentic to the fossilization process and therefore sometimes undesirable.
  • Crinoids seem to handle it far better than most and show high levels of detail after the bath.
  • Rugose coral cleans up very nicely in the solution, but you will need to regularly brush them clean as the solution reacts heavily with the quartz crystals and other calcites that typically form inside the coral. This creates a new white/yellow mineralization on the fossils which will easily wipe off. (Just know that if you're seeing a lot of this new crystallization, it is a good idea to rinse them and stop the reaction as it's technically dissolving away and reforming material that might be desirable in the finished fossil.)
  • Another thing to be mindful of is that the peracetic acid reacts with the pyrites that are also common in the Penn Dixie rock. It will oxidize the iron pyrites, which will then need to wiped clean of oxidization after the rinse.

 

I haven't tried this solution on a trilobite yet. I've recovered trilobite plurae in the sediment and it seems to not damage the fossil, but I would imagine that the loss of the supporting matrix would be detrimental to the context, stability and overall appearance of a decent trilobite. I may run a few cephalons tonight just so that I can follow-up with a definitive answer for the group. I know @Kane had tried something similar with negative results, but I think we were using different solutions. I will give mine a try and report back. I have actually been wondering if using the solution in very small amounts on a q-tip applied the exposed surfaces couldn't be an alternative to risking the detail work by mechanical means. Have been afraid to try it on anything nice, but I recently pulled some partials that I can test with.

 

I'll try to keep updating as I refine the process.

 

Jay A. Wollin

Lead Fossil Educator - Penn Dixie Fossil Park and Nature Reserve

Hamburg, New York, USA

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6 minutes ago, DevonianDigger said:

despite common belief, intimate relationships with chemical reactions do not typically result in super powers. Don't light it on fire and DO NOT feed it after midnight.

 

 

 

 

So, are you saying that bombarding myself with gamma rays is NOT going to make me large and green? Marvel Comics are lying to me? Say it ain't so! :P

 

A beautifully detailed how-to guide, and my thanks for your posting this. My own attempt used cleaning vinegar at a concentration of 10% (it's our cheap, enviro-safe go-to all purpose cleaner in our household, particularly ideal for those who might have chemical sensitivities). As they say, the poison is in the dose, and in my case I had left them stewing in the vinegar solution for too long without checking in often enough. 

 

And so this is VERY important:

"For the first few hours I check it every hour or so and agitate the sample to encourage the sloughing of the dissolved material while also taking a soft toothbrush to the surface of larger samples to encourage the breakup of the the thicker layers of matrix that forms directly on the fossils (especially on brachiopods.) I also use a tweezer to remove any fossils which have already broken free and are clear of excessive matrix."

 

I'm going to whip up a batch and try this out on some test pieces. Given the stronger vinegar concentration I am using, I'll have to modify your formula to fit.

 

...How to Philosophize with a Hammer

 

 

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important note: it probably goes without saying for most people, but for anyone trying this out for the first time, DO NOT use this on bone material. Bones are high in calcium phosphate which the acetic acid will also dissolve.

Jay A. Wollin

Lead Fossil Educator - Penn Dixie Fossil Park and Nature Reserve

Hamburg, New York, USA

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