Gpr For Crystal Pockets? in Rocks, Minerals, Gems & Geology Posted March 5 I’m a newbie and saving up to buy my 1st metal detector. Meanwhile I’m rockhounding a lot. I’m curious if folks have successfully applied portable ground penetrating radar (or other portable detecting devices) to predict likely location of crystal pockets in the hard rock, like in dolomite (for locating pockets of Herkimer Diamonds) or in granitic pegmatite (for locating pockets of gem tourmaline crystals) ? Any pointers would be appreciated.