Again on ground mineralization, VDI (GND) number..etc.

[akille68]

Jeff Foster in his "The MXT edge" states that ground -GND VDI- readings in Prospecting program do not show the strenght of the ground mineralization but the ratio of magnetic ferrous material vs conductive material (salt).
From this principle He concluded (in a 3d on White's official forum) that is not right to connect "hot soil" to high GND VDI numbers. (Usually users considered readings of GND from 50 to 60 gentle mineralized ground; 60's-70's mild; 77-80's hot.).
But...In his book (pag 71), he writes " In mineralization where iron-based mineralization is dominant, the GND number will be high..." and again "In many instances where the ground mineralization is strong, often it is due predominately to iron- based mineralization..."
So..what?

 

[Horsesoldier]

Not to dispute Jeff Foster but I know for a fact that the ground phase does in fact reflect how "Hot" the ground is. Here in SC it averages 55-68. In Virginia its 75-85+ in some areas which is consiedered highly mineralized soil. I'm sure others here will concur. However, just like with the targets in the ground, the VDI is nothing more than a reference. The only thing it effects is tracking and ground balance (and with the MXT if your tracking then it is ground balanced). The only relevence I have found in relation to the MXT is to track or not to track. If you are seeing rapid changes in mineralization then you should probably track. Otherwise you may notice the machine will start falsing or become unstable. If the mineralization is consistent then there's really no need to track. This can also effect target masking through mineralized soil. One way that I have found to help this is to set the coil on the ground next to the target, allow the machine to track, lock tracking, and then sweep the target again. It should ring in loud and clear. Just my humble opinion of course.

 

[Rob (IL)]

This could be in Jeff's book but that is not where I got it. It's in my MXT stuff from e mails Jeff sent me.
(1) Mineralized soil is soil that contains stuff to which a metal detector

 

[arizonaames]

From practical experience at finding nuggets in the field, I can say that all of the gold nuggets showed 10% iron. It did not make a difference whether there was a lot of mineralization or not. The SAT and auto ground balancing will smooth out the tone. I found 4 nuggets in NV. One was 3/4 oz, 2 were the size of my little fingernail and the last was a wee picker that was probably 1/4 grain. I had the SAT turned all the way up on Super SAT and the gain above preset. I found that the 6x10 dd coil was best. Remember that the pinpointing fuction does not work in prospecting mode. Pass over your target at 90 degree angles to pinpoint your target. Use a plastic scoop or a plastic cup to find the target. Happy Hunting......jim

 

[akille68]

This could be in Jeff's book but that is not where I got it. It's in my MXT stuff from e mails Jeff sent me.
(1) Mineralized soil is soil that contains stuff to which a metal detector

 

[Rob (IL)]

Both examples are 50 lbs. It wouldn't matter if it was 500lbs. The VDI is only giving a ratio. Jeff has a way (procedure) to figure out the real mineralization for the ground with both an MXT and DFX. It works and doesn't use VDI numbers. It is not just theory. I used it all the time with the MXT to decide whether to switch between a concentric to DD coil.

But then like Bob Canaday (rcsnake@whites) says, "What do I know".

Rob