Thread: What hone is this?

Couple questions about a hone I have. It was my grandfathers then my fathers. Different grit on each side coarse/fine. They used it with oil for knives and such. The fine side has a bad concave to it so I'd like to lap it (if possible).

1. What is it?
2. Is it worth lapping?
3. Will lapping it with a norton 320 render the 320 useless since the hone has been used with oil primarily?

Thanks!