Thread: Emerald green hone?

I have been looking for a Charnley Forest as a finisher for a while but the end price is just to high for me right now with summer coming up.
Yesterday I snagged this beautiful stone of the bay pretty cheap. It was described as green slate wetstone oilstone and it seems like there is oil residue on the surface.

I know CF is not slate but on the other hand I have no idea what slate is supposed to look like. It doesn't seem to have the characteristic purple streaks that is common to CF so I don't believe it's that. So what are everyones thought about what it can be based on the pictures. Charnley Forest, Llyn Idwal, Cutler's green, unknown welsh slate or something else?

One more thing, if it is oil on the surface and the stone can't be removed from the box what would be the best way to clean it?