Can i make a pipe out of fossil-bearing siltstone?

I have a piece or rock and i am pretty sure it is siltstone, it seems easy enough to carve because i already have the bowl carved and only need to drill the actual pipe part and the carb. would this be safe to use? is there any way that i should treat it before i use it?

Edit: do i have to seal it with oil or wax or anything like that?

Edit2: Done http://imgur.com/a/YInmE