There are a few ways you can go to be rid of this pest. You can inject it with kalk paste. You can inject it with boiling water. You can get some Joe's Juice from your LFS. You can boil the rock which is kinda radical if you only have one. Or, you can get out the blow torch and be done with it. I'm sure there are a few other options like putting the rock in the garbage but I like the blow torch best.....
No matter which method you chose, chose one. This is a pest that takes the fun out of the hobby for a lot of people.
Scott