Here is what I did last weekend.Getting ready to make a turkey tail point out of some Texas river, and thought if it was heated it would make it easier on me. This rock is very stubborn. I'm sure many of you have done this and there are many different ways to heat treat. For those of us who can build a fire outside this is what I've done. First clean out the fire pit, dig out about two inces of dirt, no need to build a warm up fire because the ground here is very dry. Place the stones in the pit, Ive picked out several different types to see the affects, some are very hard aggate that I havent been able to do anything with. Cover them up and start the fire. I started the fire on Friday evening after work about 5:30 and kept feeding it until bed time at 11. Saturday at 5am, while on my way out to the deer stand, I piled wood on and made sure it reignited. Then kept it going until about 2pm saturday afternoon. Let the ground cool till monday after work and heres what I got. Only one piece of texas shattered but it broke into usable pieces.