Found in the wild

[Hair apparent]

Went into a country antique store, nosing around, asked if they had any sharpening stones. Needs to be lapped, but was excited to find a honking big rock I believe to be a coti. Am I right, and any idea what kind it might be? Haven't measured it, but appears to be around 60mm x 200mm.

 

[Wid]

I'd say you're right on your guess. Other than saying it's a natural combo there's no way to identify a vintage coti. Good find, congrats.

 

[Gamma]

Nice score - does look like a natural combo to me also.
Very cool looking top. I never see stones like that in the wild. Excellent find.