How can I clean these marine shell fossils?

[Chrysalyst]

I'm assuming these are truly fossils....Are they covered in calcification? Is there something that can help remove this? Anyone know how old these may be? I have a few (not pictured) that still have both sides attached and are not broken...

 

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[old digger]

Try using hydrochloric acid diluted with water (at least 50 %). Dip the items in the solution for a shot while and then rinse it in the water and wipe clean with a paper towel. Repeat until you get the desired appearance. This might help, but use some rubber gloves and be cautious of the fumes.

 

[smokeythecat]

I don't think I'd clean them. How old they are depends on the context they were found in. There are a lot of Miocene era and Pleistocene era shells like this.

 

[Madmox]

Citric acid or Acetic Acid will work too. A lot is dependent on the sedimentary binder of the strata. Some of those most common ones are silica and calcite. Both of those should work on calcite binders and aren’t too harsh. I imagine it will work on silica binders also, I’m just not too sure how fast.

 

[Megalodon]

We find these with fossil shark teeth in Miocene strata of Calvert Cliffs. Nobody here cleans them.

 

[Chrysalyst]

Thanks! I will try that. I've chipped most of the calcification off and the shell itself is invincible!

 

[Chrysalyst]

Where exactly is that? And how old are these, if you'd happen to know?

 

[Chrysalyst]

Thanks!

 

[Chrysalyst]

They happened to be dredged up when more sand was added to the beachfront on Isle of Palms.

 

[Megalodon]

Calvert Cliffs have some of the best fossil grounds for marine fossils in the US. They are along the Chesapeake Bay and some of the rivers, such as the Patuxent and Potomac. The Cliffs along the Bay are a short walk from my house.

These shells are found in the lower part of the formations (locally the Calvert, Choptank and St. Mary's formations) just a bit older than the shark teeth. So, mid-Miocene for the shells 13.6 - 11.6 Million years ago, just a very little older than most, but not all, of the fossil shark teeth.

The fossil shells like you have found are sometimes dredged and dumped in the Bay and rivers, used as substrate for oyster larvae to attach.

https://en.wikipedia.org/wiki/Miocene