Is this a fossilized egg in basalt?

[AndreaHiker]

This looks like a fossilized egg in basalt or other rock but the pics I've seen of fossil eggs look brown. This is white and rock hard. I found it near the eastern end of the Mogollon rim in Arizona. Can anyone ID it?

[Fossildude19]

Hello, and welcome to the Forum.  

 

I don't think it's an egg - wouldn't survive immersion in the magma that turns into basalt.

Not sure that is basalt, though. Looks more like a sandstone conglomerate - so the "egg-Like" item may just be a cobble, or concretion.

You can see the indents where the other rocks fell out. 

 

I also don't see any eggshell texture.  

Let's see what the others say. 

Regards,

[ynot]

Agate nodule in a volcanic rock. May be basalt or rhyolitic lava.

Look for geodes (hollow agate nodules) in the area.

Tony

[DNF]

13 minutes ago, ynot said:

Agate nodule in a volcanic rock.

 

Very interesting. The rhyolites I encountered in New England had tiny voids (or vugs, as I now know they are called) with nothing in them.

 

I didn't realize that agates and other gemstones could form in the vugs.

 

http://geology.com/rocks/rhyolite.shtml