How to deal with Cold or Negative rocks

Cold or negative rocks are those that give a loud boing and register 00 on the AT Gold.. They GB at 70+ They are magnetite I believe.........as against hot rocks that register like a nail etc....
How does everyone deal with the cold rocks... I have done things like up the GB a few points and increase the GB window but am interested in any other suggestions. I can invariably identify them as NOT a target due to the sound and they way the signal rapidly dissipates when the coild is lifted but more information would be great....The fact is though the boing noise is a pain in the butt!!

Dave

You cannot escape the Auto Threshold retune boing when you hit a  negative hot rock. That is the result of the retune overshooting the set threshold level as the coil passes away from the rock. The boing does  not occure with Manual retune detectors. With these you will either get a positive going threshold or a negative going threshold, depending on the type of hot rock and the GB setting.
If you can GB the rock then it may or may not contain gold. some very small gold can be GBd out or masked by the GB setting or hot rock signal.
The fact that the rock causes a boing sound tells you it is a negative hot rock.
If you select DISC 1 and rescan the rock and the rock still gives an imediate  positive signal then it would be wise to check it out. If the threshold remains the same or goes quiet then the rock has the same or less metal in it than the zero disc setting of DISC 1 can recognise as metal.

Not sure if that makes any sense to you I thunk ov ut an wrote ut an I avent got a clue wot ut means

Hey what you say makes sense......it all helps...thanks