Actually, I don't have a fire pit. What I have is what I call a fire hill. It is composed of 5 slate rocks about 10 in. thick raised 16 inches above ground level. Its about 5ft. by 10 ft. No problems with exploding slate so far and there have been some real nice fires. Used the tractor loader to bring in the wood. The setup doesn't allow the the base to get all that hot and allows lots of air for a good fire. It's also a good place to dry wet boots and warm the feet on a cool evening.
Egon