Pearly-white, flaky mica like material ?

[Rocky Stoner]

Greetings friends.

Of the many, many fossils I've exposed here, this is the first I've seen any material like this.

I hope the pics can capture it, it is actually near snow white.

Its pearly white, has an apparent directional grain to it, is loosely layered and is very fragile.

It can be scratched/scraped,dug up with a tooth pick.

Is there a common name or process associated with this material ?

This has filled the void left by a shell.

Very cool. Puts you in mind of an actual deteriorated shell.

Thanks.

[izak_]

I think its a shell.

@ynot

[Miocene_Mason]

Probably calcite replaced

One way to test this is take a piece and place it in vinegar, see if it fizzes.

[Miocene_Mason]

Diagenesis is replacement with a different mineral.

[Rocky Stoner]

7 minutes ago, Foozil said:

I think its a shell.

@ynot

 

12 minutes ago, WhodamanHD said:

Probably calcite replaced

From wiki :  Calcite is often the primary constituent of the shells of marine organisms .................

 

Could this be the remnants of the calcite from the original shell ?

[Miocene_Mason]

Just now, Rocky Stoner said:

 

From wiki :  Calcite is often the primary constituent of the shells of marine organisms .................

 

Could this be the remnants of the calcite from the original shell ?

It is possible but unlikely, calcium rich water seeps through the ground all of the time, being from shells, bones, preexisting deposits, etc.

[Miocene_Mason]

Calcium carbonate makes up bones, shells, and mineral. It is one of the main components of life. The Permian extinction is to be in part due to carbon dioxide dissolving in the oceans (to create carbonic acid) and neutralizing the water, turning the calcium carbonate to a hydrated version that cannot be used by plankton or any othered shelled living things, the basis es of the food chain.

[Rocky Stoner]

Thanks.

Just strange, this is the only one of literally thousands of fossils exposed right here in the same strata that contain this material.

Very strange.

[Rocky Stoner]

55 minutes ago, WhodamanHD said:

Probably calcite replaced

One way to test this is take a piece and place it in vinegar, see if it fizzes.

Yup, it does fizz in vinegar.

Thanks again,

[ynot]

1 hour ago, Rocky Stoner said:

. Puts you in mind of an actual deteriorated shell.

That is because that is what it is.

It is not uncommon for the original shell to survive for a long time (fox hills, South Dakota.).

When a mollusc grows it lays down thin layers to its shell. As it decomposes the bond between layers will breakdown and allow the layers to separate (like mica). 

When a shell is replaced (even by calcite) it losses the layering and becomes a solid mineral  (single layer).

Most of the pieces that You have posted are the print of the shell. And the shell has leached away and some oxidized iron has been left in the void, but for some geologic reason this one shell managed to avoid the processes that removed the other shells.

[Rocky Stoner]

That is exactly as I was imagining, (having shucked several bushels of oysters in my time) thanks for chiming in !

A sole survivor ..... so far.

Great info from all !

[Herb]

looks like the original shell material survived