Howdy Smudge... Actually it is a refinement of an old trick that gold prospectors have used
beginning with the BFO's and now with the VLF's. Bar graphs display the amount of magnetic
susceptibility in the soil under the search coil regardless of the soil type... The target ID also is
the Phase reading that indicate the type of ground that could be associated with higher
concentrations of magnetic black sand...
In theory it assumes placer gold may be associated with black sand (magnetite) due to specific
gravity. It depends upon the metallogenetic area as not all black sand can carry any associated placer
if the detectorist is working a barren non-metallogenetic area.
This 'trick' can work out in the Californian mother lode alluvial 'wet-placers' but it works better in the
eluvial 'desert-dry-placers' especially eolian-type where strong winds blow away the
fines leaving a higher concentration of the heavier metals and non-magnetic black sand... incidentally
over the past years, 'electronic gold' prospectors have taken time to rake the surface 'desert
pavement' resulting from wind-erosion over the eons of time. They rake the desert pavement into
windrows and detect the spaces between.
As a well-known example, If you are ever in the Middle-Camp area south of the Dome Rock exit
(mile post "10) west of Quartzsite you will see large mosaics dating back to the 1980's as mostly done
by 'the mad raker' as he was then known.
If you happen to be detecting in a dryplacer area for detectable gold and using the Gold Bug Pro and
pumping the ground as in ground balancing each pump will give you a 'snapshot' of the soil as found
to the depth of your searchcoil. The more bars displayed and a phase reading of about 75+- range could
be a good area to condentrate in, if'n you are in a placer gold area... There exists a mid-range area of
"bread and butter" nuggets that can be found by concentating (cherry-picking) such areas.
Just my thoughts due to past experiences over the years....
