Re: Just what is it highly mineralized ground and how I tell ?
Hello there Marty....
In metal detecting terms, mineralisation specifically refers to the MAGNETIC class of minerals found in the ground.
There are many other minerals.(Of no comparable consequences.)
The main one most detectorists are familiar with, is named as FERRITE; and identified by the formula / code, Fe3 O4. (Ferrous and oxygen)
It has a very strong magnetic influence, and so affects the INDUCTANCE value of your detector's search head.
The effect is detrimental to the normally balanced state of the coils, required for sensitive searching.
It reduces the penetration of the magnetic search-field'
It also 'biases' the resultant signal evaluation (VDI), produced by the detector's system.
I hope that is sufficient an answer.....too much of a detailed reply may add confusion rather than help.
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HOW to BE AWARE OF THE PRESENCE AND 'LEVEL' OF SUCH MINERALISATION...?
As implied by other replies, the best indicator is the AUTO LEVEL reading...i.e. the right-hand-side one, shown in the sensitivity panel,
and adjacent to the manual sensitivity setting chosen by you the operator.
'Average or NORMAL ground mineralisation levels produce an AUTO reading of about 16.
As Fe mineralisation INCREASES, so the AUTO reading DECREASES..falling to levels of 12 or less as the mineralisation severity increases.
Hope that brief explanation helps.....Matt.