Inside the sixties, the first industrial metallic detectors had been produced, and they ended up extensively employed for mineral prospecting together with other industrial applications.????? ???? ????? ??? ??????? ??? ????? ?????? ??? ????? ??? ??????? ?????? ??????? ??? ??????? ????? ?? ???????.???? ???? ??? ????? ???????? ?? ???? ????? ?????? ??