Well its not so much about the Iron as it is the combinaiton of the Iron, Rust, Soil Conditions/mineralisation, effect of the rusty iron reacting with the soil, depth, other nearby targets, atmospherics.... etc etc
I have done about 5 years of gold prospecting before this, first with an SD2000 then a SD2100 then a GPX4000.
I think it was an excellent primer for treasure because the degree of attention you have to pay to pick the minute changes in the threshold hum of a deep nugget gives you a mindset that makes you a lot more careful than many treasure hunters I have seen who havnt detected for gold with a PI machine.
The point of that ramble is this. No matter how good your detector, now matter how advanced, no matter how much discrimination you employ, your going to detect targets that are not what your looking for and the type of metal involved is only one factor in the mix. If you start convincing yourself you can identify every target without actually digging it, your in danger of walking away from potentially great finds, that at first sound like junk. Equally your always going to dig utter garbage that sounds like treasure. With experience, your going to be able to start making a call about whats below your coil, as your confidence increases you will only dig the bad sounds every now and then to just confirm you still have your "mojo". So eventually you will be walking away from bad signals with a high degree of certainty that they are in fact ok to walk away from.
One of the most important things you can do though to reach this level is STICK WITH IT! Pick a machine and learn it inside and out.
One of the best gold prospectors I know, who I have personally seen his collection of over $100,000 AUD in nuggets and speccys, still uses a GP Extreme..... why ? Because he KNOWS IT. I let him use my GPX4000 for almost a whole day, he liked it, and could see the benefits, but he didnt like the idea of totally re-learning a new machine and maintained that until he "has to" he wont swap. Being familiar with your machine and what its trying to tell you is in my opinion far more important that what machine your using.
Almost every good day I had with the GPX4000 could have been done with the SD2100 and many many gold detectorists will tell you the same thing about their current and former machines.
Having said all that.... if your looking to sell your Etrac... gimme a PM
