Crystallized oyster shell?

[Nicole-johnny]

Shell right side of picture .. Can someone explain if this is common to find this fossil crystallized inside the shell where the meat was exposed? 

Nothern california , along eel river scotia bluffs area. Thanks

 

[Brett Breakin' Rocks]

Hi there ..... calcite filled clams are fairly common in certain locations.  The calcite grows inside of the cavity left vacant by its former occupant. It might be more uncommon in your area, just depends on the geology and how the bivalves were fossilized. Rucks Pit in Florida is well known for calcite filled bivalves like yours and they are beautiful. 

 

I picked up one of these in Tuscon many years ago. The two guys selling them were getting them from the gravel quarry.  I wonder if the guy I met was Eddie Rucks (Hunh ?) Anyhoo, they told us when buying at the time that they hopped down into the quarry and rescued as many of these as they could on the weekend and off hours.

 

Normally everything was broken down and used as infill and road bed if I'm not mistaken. This is an example.

Image Credit: https://picclick.com/CALCITE-crystals-in-a-Fossil-Clam-shell-142633689603.html

[Nicole-johnny]

Thanks so much!! Great information !

[ynot]

Welcome to TFF!

These clam geodes are not rare along the california coastal mountains and shore line exposures. Though they are seldom as showy as the ones from Florida.

Yours are pretty nice.

[abyssunder]

I think, the determination is right.
You have the botryoidal variant vs. "dog tooth".