Posted by Sean on 3/21/2008, 5:00 pm, in reply to "PI - iron mask and "orphan" silver"
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Hi Lytle. You mentioned: a "very substantial numbers of “orphan” silver coins masked by iron - and masked in such a way that even "beep - dig" techniques didn't detect them??"
Short answer, no. but.. there are a few factors you have combined in your post. If one were to throughly grid off an area and, "clean it out" with a good quality vlf in "True All Metal" or "Pin point mode" then the main reason a PI would get any deeper is because the ground is mineralized and the PI is not affected by mineralization. (This is assuming they have same coil size and are similar quality machines.)
This concept can be a little missleading because, on some machines, there is an "all metal" mode that is not completely true all metal. Even at its lowest discrimination setting it still discriminates some small iron. Some of the Tesoro's where made this way. As a result any where there is ANY amount of discrimination there is some masking.
A good quality, true all metal ground balanced, "beep dig" technique does not suffer from masking.
This brings you to the 100Khz machines that because of the high frequency could not generate enough "eddy current" on smaller iron to mask or override the "eddy current" singnal from a silver piece next to the iron, unless it was of considerable size compared to the silver but, the same high 100khz frequency cannot penetrate deeply through the iron minerals in the soil. The electromagnetic flux is reflected off to the sides and back towards the surface.
Summary:
PI is the complete opposite of 100Khz TR
PI completely ingores the iron mineraliztion, penetrates deep and, can't easily or acurately distinquish or discriminate small iron to any real depth.
100khz TRs in all metal will naturally ingore small iron but naturally can't get through the iron mineralization.
Common Vlfs are in the middle.
That's why the biggest break through will be a PI with VLF quality disc.
I agree with the notion that these machines are going to be to deep for most modern use parks.
If you've ever dug a silver quarter at even a true measured 9 inches with the average hand tool!!..that seems preety darn deep already!
Then again, in some areas with such high mineralization no VLF machine has reached down into yet.. That may be a Gold mine.. for Silver...
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