Hot rocks are normally a product of to much sensitivity. So..... things to try would be IB, recovery, run in beach mode, ..... and lastly reduce sensitivity you are running.
Hey Tom, yea hot rocks are a problem on the beaches of Mass. Florida guys just don't get it. I have yet to find a detector that can handle them well. I also am about to order and try a Nox800. Let us know how you do if you beat me to it.
My Cibola liked hot rocks in New York state at that one place, but I could tell which was a hot rock and which was metal the way the machine "rang" when it went over the hot rock. Now my Deus does that same thing, in our camps we have to go very, very slowly to pick out the buttons out from between the rocks.