Identification of Hot Rocks

If you ground balance your metal detector the right way in order to compensate for high mineral background it will cause it to give a metal response to hot rocks. This takes place because hot rocks are basically isolated minerals for which the detector will not be ground balanced for. Thankfully the modern metal detectors are very effective at identifying them now as long as they are accurately adjusted. 

Remember the importance of having the right design and accurate calibration by its manufacturer for universal use, as well as prospecting. Not all metal detectors are appropriate for prospecting.

The method for identifying mineral hot rocks is not as difficult as it was in the past, but it does require practice. In order to check to see if the response is a metal or mineral one you will need to spot your target with the detector in the all-metal mode. Then move the search coil to one side, then lower it a little bit and switch it over to the discriminate mode. The discrimination controls should be set to the level that the manufacturer specifies as the calibrated level for sampling ore. Audio retune the detector if you need to according to the instructions of the manufacturer. Now that you have a consistent sound coming from the detector, pass the search coil over the target. Make sure the search coil is at the same distance from the ground as we previously mentioned. Keeping the search coil at a same height might require a little bit of practice at first but it can be done. If the level of the sound goes down or silent, it means the target is oxides or magnetic iron ore. Keep in mind that these will be the only types of substances that will cause the signal to stop completely. When this occurs, just move on and switch back to the all-metal mode and continue on with your search. It means you have just identified a hot rock.

If however, the signal on the detector increases or stays steady, the target is worth being checked out. Increase the changeable discrimination control to establish the amount of conductivity in this target. This method shows you why it is important not to prospect with a metal detector that has a fixed discrimination control. If you have already practiced using varying discrimination, you will already be aware of the approximate point on the control where insignificant pyrite will be discarded. If you keep on receiving positive response after you have passed the setting, then it is very likely you have found a non ferrous pocket or vein of conductive ore and you may have just found what you intended to find, gold.