Pyrite Paraspirifer?

[Mochaccino]

Hello,

 

I'm looking at this ~5cm Ohio Silica Shale Paraspirifer bownockeri. I was wondering if such bright gold coloration indicates "enhancement" of the pyrite by harsh prep, acid treatment or brass wire brush? Or is this just the natural color of some specimens? Many pyritized Paraspirifers I see are more grey or silvery (though I have indeed seen such gold ones). Other pyritized fossils as well seem to typically be more the silver/grey color, and as far as I can tell Pyrite itself is generally paler than a vibrant gold.

 

Thanks.

 

 

[Northern Sharks]

From what I've heard, these brachs are acid etched to remove the outer gray layer revealing the natural pyrite inside.

[facehugger]

Awesome fossil!

 

Keep in mind that if you expose all the pyrite, and you live in an area with high humidity, you may be exposing the fossil to potential for pyrite rot, and you should probably seal it with something afterwards. I think there is lots of discussion on pyrite rot on the forum for further research. 

[Mochaccino]

3 hours ago, Northern Sharks said:

From what I've heard, these brachs are acid etched to remove the outer gray layer revealing the natural pyrite inside.

 

I see! So this gold is possibly due to a destructive process on the fossil. If one prefers the most natural fossils then I guess it would be a no-go.

 

3 hours ago, facehugger said:

Awesome fossil!

 

Keep in mind that if you expose all the pyrite, and you live in an area with high humidity, you may be exposing the fossil to potential for pyrite rot, and you should probably seal it with something afterwards. I think there is lots of discussion on pyrite rot on the forum for further research. 

 

It does look very nice, I just wish it wasn't overprepped through whatever method! Yes I'm also wary of pyrite rot as well. If I do get a fossil with such exposed pyrite I'll look into taking special measures.

 

Thanks

 

 

[connorp]

6 hours ago, Northern Sharks said:

From what I've heard, these brachs are acid etched to remove the outer gray layer revealing the natural pyrite inside.

Do you have a source for this? Not trying to call you out or anything, just curious. I know some people will use a strong base like potassium hydroxide to remove the shale on Silica Shale brachs, if done correctly this should not damage the fossil. Is this what you're referring to, or something different?

[Northern Sharks]

12 hours ago, connorp said:

Do you have a source for this? Not trying to call you out or anything, just curious. I know some people will use a strong base like potassium hydroxide to remove the shale on Silica Shale brachs, if done correctly this should not damage the fossil. Is this what you're referring to, or something different?

I forget who told me about using acid to expose  the pyrite, but that is very different from using potassium hydroxide/ Quaternary-O/ Rewoquot etc. I used to see ones like in the OP at shows fairly frequently but it took me a while to find one that wasn't etched.

 

[Misha]

Here's a Paraspirifer I have in my collection, definitely not acid etched or anything as you can see it still has shale on it and the epibionts which I don't think are pyritized:

You can see slight shimmers of pyrite, but definitely not as much as in some of the other pieces I've seen online

Edited March 24, 2022 by Misha

[Mochaccino]

7 hours ago, Northern Sharks said:

I forget who told me about using acid to expose  the pyrite, but that is very different from using potassium hydroxide/ Quaternary-O/ Rewoquot etc. I used to see ones like in the OP at shows fairly frequently but it took me a while to find one that wasn't etched.

 

 

6 hours ago, Misha said:

Here's a Paraspirifer I have in my collection, definitely not acid etched or anything as you can see it still has shale on it and the epibionts which I don't think are pyritized:

You can see slight shimmers of pyrite, but definitely not as much as in some of the other pieces I've seen online

I see! Yes these do seem different from the very golden ones. Consistent appearance/color as this one I have that I know is definitely not acid-treated (also has the remains of an inarticulate brachiopod epibiont):

 

 

I guess this is the more natural look of these. However I'm now wondering if the one I originally posted simply has some pyrite flakes covering it as opposed to being acid etched, as you can see underneath the flakes that same grayish color and texture of the shell...what do you think?

 

 

 

 

 

 

Edited March 24, 2022 by Mochaccino

[FossilDAWG]

I'm not sure about how these brachiopods are treated to expose the pyrite, but I do want to say that silica shale pyritized fossils are highly resistant to pyrite disease.  I have never seen one with this problem.  There are different chemical types of pyrite, and some are highly resistant and some are very susceptible to pyrite disease.  Silica shale fossils are in the first group.

 

Don

[Mochaccino]

1 hour ago, FossilDAWG said:

I'm not sure about how these brachiopods are treated to expose the pyrite, but I do want to say that silica shale pyritized fossils are highly resistant to pyrite disease.  I have never seen one with this problem.  There are different chemical types of pyrite, and some are highly resistant and some are very susceptible to pyrite disease.  Silica shale fossils are in the first group.

 

Don

Very hopeful news. Even on ones supposedly acid-etched to reveal pyrite? I guess the type of pyrite in Silica shale fossils is fundamentally different than vulnerable ones.

[FossilDAWG]

I have had some Silica Shale pyritized brachiopods that look like yours for more than 20 years exposed to Georgia (USA) humidity and warm temperatures without a sign of pyrite disease.  In the same time some French ammonites turned to dust.

 

Don

[Misha]

Yeah, I agree with Don.

Pyrite disease isn't a major concern with these, mine is from an older collection and has no signs of any of that. I've never seen any with pyrite disease.

[Coco]

I think the pyritized fossils that are resistant to the disease have a much lower sulphur (S₂ in "FeS_2") level than the other ones.

 

Coco

[Mochaccino]

7 hours ago, FossilDAWG said:

I have had some Silica Shale pyritized brachiopods that look like yours for more than 20 years exposed to Georgia (USA) humidity and warm temperatures without a sign of pyrite disease.  In the same time some French ammonites turned to dust.

 

Don

 

4 hours ago, Misha said:

Yeah, I agree with Don.

Pyrite disease isn't a major concern with these, mine is from an older collection and has no signs of any of that. I've never seen any with pyrite disease.

 

1 hour ago, Coco said:

I think the pyritized fossils that are resistant to the disease have a much lower sulphur (S₂ in "FeS_2") level than the other ones.

 

Coco

Great, so no big concern about sealing or anything. Just gotta stay away from those French pyritized ammonites I guess!

[Coco]

Hi,

 

Not necessarily. There are sources without problem. Besides, if your ammonites smell strong of sulphur, there is practically nothing to do to avoid their destruction.

 

coco