Sounds like you are on the right track. Many LRL's will pickup signals form precious metals, and too often other metals as well. More often than not, the distinguishing features that separate the top ones from the others are their discrimination abilities. When perfected(real world), they should only detect a significant amount of whichever metal is programmed or witnessed, although some have the capability of detecting more than one metal/mineral art a time. Good luck with your project and hopefully you can succeed in your quest for the holy grail of LRL's. rockhound