How could I go about preparing this brachiopod?

[Misha]

Hi guys!

I am not sure if anyone has encountered such fossils before but when collecting fossils at the Salons Formation in PA this summer I found this brachiopod:

This brachiopod is nicely inflated and has great detail, one problem is that the surface of it is covered in this layer of limestone with patches of calcite. I would love to get rid of it but I am really not sure how to go about doing so.

Here is an extra picture of how it looks up close:

Any help would be appreciated,

Thank you!

[LabRatKing]

Dental tools, dissection tools, air scribe, abrasive blasting, and acids. There are pros and cons to each and varying levels of cost, time and risk to the specimen. have a go at the preparation threads...there's lots on this topic in there in great detail!

 

http://www.thefossilforum.com/index.php?/forum/170-fossil-preparation

[Tidgy's Dad]

I think I'd start with a light hammer and a nail.  

[Misha]

21 minutes ago, LabRatKing said:

Dental tools, dissection tools, air scribe, abrasive blasting, and acids. There are pros and cons to each and varying levels of cost, time and risk to the specimen. have a go at the preparation threads...there's lots on this topic in there in great detail!

 

http://www.thefossilforum.com/index.php?/forum/170-fossil-preparation

Yes, I generally use scribes and picks to clean fossils.

I have never tried to attack one in limestone like this though and the calcite layered on it adds additional complications as I have never encountered it before and am not sure about how hard it is compared to the fossil and matrix.

[Misha]

12 minutes ago, Tidgy's Dad said:

I think I'd start with a light hammer and a nail.  

That's a good idea, I haven't tried the nail technique yet.

I will get some practice on another piece of this matrix first.

[Tidgy's Dad]

1 hour ago, Misha said:

That's a good idea, I haven't tried the nail technique yet.

I will get some practice on another piece of this matrix first.

Probably wise.

[LabRatKing]

Nails can be a bit soft, but a "blued" finish nail is made from harder tool steel and works fairly well. However a set of "gasket picks" from the autoparts or hardware store will only set you back the cost of a Big Mac, and work really well.

[minnbuckeye]

22 hours ago, Misha said:

nail technique yet

Use a dry wall screw, not a nail. The difference amazes me. Maybe someone knows the physics of this! 

 

 Mike

[Kane]

Ugh. Dealing with calcite can be a real chore. If it were me, I'd gently "kiss" scribe the larger flakes of calcite to pop them off, and then go on the attack with an air abrader where the calcite is the thinnest and you are super close to the shell. With abrasion, angles are important; it is possible to be at a very low angle to aim the nozzle between the crust and the shell, which can then undercut the calcitic crust and lift it off the shell. Sometimes this only serves to make an overhanging "cliff" of calcite, which you could then use a dental pick to remove.

[FossilNerd]

On 11/17/2020 at 5:55 PM, minnbuckeye said:

Use a dry wall screw, not a nail. The difference amazes me. Maybe someone knows the physics of this! 

 

 Mike

I think this is because (wood) nails are made of softer steel. Giving them the tendency to bend, dull quickly, and the tip to deform. This is so they have good shear strength, when used for their intended purpose, and will bend instead of breaking under shear pressures. Plus they are less prone to breaking when hit incorrectly with a hammer (they tend to bend) and there is less of a chance of chipping the hammer face, which is harder steel than the nail.
 

Screws (such as drywall screws) on the other hand are made from harder metal. They don’t deform and dull as easily. That, along with their threads give them good gripping strength for holding things together. However, this causes them to be more brittle and lack the shear strength of a nail. They tend to break instead of bend.
 

I’d wager that the hardness of the screw would make them preform better when used to prep a fossil. The tip won’t dull as quickly and the screw won’t bend as easily when used on hard rock. However, their hardness makes them more brittle and prone to breaking. Light taps of the hammer (and eye protection) would be in order. 
 

A nail option that might preform like a screw would be a masonry or concrete nail. Those are hardened steel so as to be driving into hard masonry and concrete.