Mortor & Pestle...

I just bought a really cool mortar and pestle on sale that is made out of volcanic rock. I'm thinking to myself how cool is this? Till I get it home and realize hey, how can I use this (it's made of volcanic rick) therefore it is very "holey" no pun intended. I though about "sealing it with paint or something but, if I'm going to be grinding this wouldn't really work unless I want to eat paint, lol. the pestle is "holey" also so I think I'm going to have a fun time figuring out a solution. any advice would be appreciated. So far I've just had to line it with wax paper surrounding the thing I'm grinding and this isn't going to work for the long haul...This is probably posted in a bad place but, I couldn't think of where to put it so if it needs to be redirected go for it.