Quote Originally Posted by kelbro View Post
On this monitor, it looks like the one on the right is a slate of some sort.

Those two stones could do you well with razors. Both would probably need to be lapped flat.
Slate. I think someone said the base of my Coti was slate so I'll have to take a second look at it and see how it can be utilized.
The black stone was pretty flat on top except for the scratches, but you can actually see in the pic how convexed the left stone was. After lapping I'm not sure if there would be enough left to bother with.