Fully agree with you Paul..
While on the subject, let's think out-the-box a bit...
Military and counter terrorism have for years used "bio-detectors".
Rats have been extremely successful in Cambodia in sniffing-out mines that detectors cannot find (low/non-metalic mines).
CT forces have demonstrated that honey bees are 100's if not 1000's of times more sensitive in detecting explosives and also way quicker than traditional ion-scan methods...they can do a complete warehouse in couple of minutes...
myself have seen a dog on the beach that only digs-out rusted iron bits, sometimes at depth 200 - 300mm...now...
My question to you Sirs: Why would it not be possible to train a rat or dog to sniff-out certain metals???
Makes you think.......