Hi Jason,
It is simple. When detecting gold, all repeatable signals should be dug if at all possible. Work in the Prospecting Mode, and forget about the VDI.
That said, I will often ignore items that give a high iron reading. Or I may even detect for nuggets in Relic Mode. I'll be heading for Ganes Creek in 9 days, and will be running in Relic mode with the disc set at 2.
If you use any discrimination at all while nugget detecting you risk losing gold, plain and simple. Try burying a nugget in high mineral ground. Usually, the deeper it is, the lower the VDI numbers will go, as the machine reads more ground and less nugget the deeper it goes. At some point many nuggets will actually read as iron. The more mineralized the ground, the less reliable the discrimination.
It is all a trade between available time, and amount of trash. If time allows, dig everything. As trash levels rise and time is less available, you can rely more on discrimination. But never fool yourself... you are probably going to pass over nuggets doing this eventually. The more you rely on discrimination, the more likely you will miss gold.
At Ganes Creek I am targeting nuggets weighing 1 oz or more and there is a lot of trash to deal with. The mineralization is very low. The area to detect is vast, and I have 6 days to detect. So I'll be digging solid, clean targets and covering as much ground as possible. Digging everything is not an option as I would waste too much time doing it. And I do not care if I miss smaller nuggets. At least, that is going to be my strategy.
When in doubt, dig it out! How much discrimination you use while nugget detecting simply depends on the situation, but as long as you always remember it is not 100% reliable and that you are trading some lost nuggets for digging less trash, then you can decide for yourself whether the trade is worth it.
Steve Herschbach
