Re: White's TDI Pro in Silver Country [including Infinium Comparison]
Howdy Jim…thanks a million for those kindly comments. You can bet your bank balance I appreciate it. As I look back in time, it is hard to imagine that I very nearly did not post this article. I felt it was too technical and lengthy…but it seems to have worked out OK.
The magnetics resulting from various iron minerals are interesting…and seriously impact what can be achieved. A result is that over the years I’ve paid particular attention to them. So, its gratifying to see that write-up attracted your interest as well. A few friends, Ty Brook and our good buddy DJ in El Paso have been quite helpful as mentors on this subject in recent years, and certainly deserve recognition here for their roles in helping me gain an understanding on the subject. These two fine individuals have given freely of their time and knowledge for which I’m very grateful.
As to undisturbed vs disturbed ground magnetic measurements Jim… frankly I have not looked further into the matter. I’ve been content to understand the differences between these soil conditions with respect to target depth and ID and apply the knowledge accordingly when in the field. I believe it has made the difference to digging good targets many times over.
I’d rather not enter the long-standing debate about what exactly is responsible for the improved depth and target ID / discrimination experienced over “undisturbed” natural ground. I don’t have a definitive answer and neither does anyone else, but I’ll make a few comments…
Many hobbyists suggest a “halo” effect as the primary reason for improved performance in undisturbed ground. Other than iron oxidation, which is essentially maghemite, I don’t subscribe to the halo theory with conductive metals. Yes, other than perhaps very pure gold, precious metals and/or alloyed constituents may very well react with chemical substances in the soil resulting in molecular leaching / deposition into the soil. However, my view is that the amount involved cannot possibly sustain electromagnetic energy in the form of eddy currents sufficient to return a measurable signal. Its tough enough for a sensitive metal detector to give a useful response to disseminated precious metals in small rocks, and certainly detectors will not respond to non-ferrous chemical residues at a molecular level IMO. But heck, I’m prepared to stand corrected by anyone at any time.
I am more inclined to a view that metal detector performance over disturbed ground struggles either from the loss of electrical alignment / continuity within the disturbed soil, perhaps further aggravated by the disruption of the magnetic fraction of a soil’s composition. That’s just guesswork. What does matter is that we can identify the effect of disturbed ground on metal detectors vs undisturbed natural ground and this phenomenon is readily acknowledged by the manufacturers as well.
Hope the weather down your way has allowed you to get out and about in the goldfields. All the very best…
Jim.
I haven't been following most of the posts too much now that summer is in full swing here in the Great Lakes area, but I seem to recall a short while back you had left for the outback in your RV. 
