Originally posted by GazimoEnthra:

Originally posted by Honorable_D:

No, they never come back.

So when you need more ore, do you just go further and further away from base?

Effectively yes. There is so much ore on a single map that you in theory should never be able to exhaust it all. That being said, I do utilize other worlds and move it between them so as to not entirely strip mine my "active" world out.