This is one of my first posts here, and I wasn't sure the appropriate forum in which to post my question. We are in the process of a complete home remodel and are trying to go as "green" as possible. We found a salvage store that has some pieces of slate we are considering using for our fireplace hearth and surround. The pieces are large, however they have some graffiti on them. We actually haven't seen them in person, only in photos so before making the trip to the salvage store I was hoping to get some information as to whether or not it is possible to remove old graffiti from slate. And if so, could someone give me some tips on how to go about it?

Also, would we want to put any sort of finish on the slate if it will be used as a fireplace hearth?

Thanks in advance!