Level of mineralisation

[wal.ellison]

Hi all,
Just a technical query about the X-terra 705. I've been in the game for more than 30 years but this is my new detector and I'm just getting to know it. I may be getting it the wrong way around, but several things I've read seem to suggest that the LOWER ground balance numbers on the machine indicate a HIGHER level of mineralisation. Machines I've used in the past have read the other way, with a higher number indicating higher mineralisation. Obviously, it makes no difference which way a particular system shows the higher mineralisation, just so long as I know what I'm looking at ! HaHa. I'd be glad if Randy or some other 705 guru could set me straight on this. Being able to actively check the mineral level of the dirt is a valuable tool in prospecting. Based on all those past years and different machines I can honestly say this 705 with both conc and DD coils is the best hybrid I've ever swung. Many thanks in advance for all advice.
All the best
Wal

 

[Digger]

As Randy the detectorist, I'd tell you to consider the numbers "backward" of what you may be use to on other machines because they do not represent actual levels of mineralization. Instead, generically speaking, they represent "compensation" for what we typcially refer to as mineralization.

As Randy impersonating a "guru", I'd again say that what we commonly referred to as the Ground Balance numbers on the X-TERRA are not the actual levels of mineralization. Instead, these numbers represent the phase angle of the ground. Phase angle is a time measurement between eddy currents generated at the transmit windings of the coil and the resulting secondary electromagnetic effect on the windings of the receive portion of the coil. When we set the ground balance, we are doing so to compensate for the time measurement beween the transmitted current and the corresponding receive current. And we want that time measurement to only be relative to the conductivity of the soil. This is why folks should make sure there are no metal objects under the coil when performing a ground balance procedure. Reason being, just as the proper ground balance setting is dependent on the phase angle of the ground, the Target ID is dependent on phase angle of the conductivity of a target in the C/T mode. Having a target under the coil when doing a ground balance could distort the phase angle of the soil by providing the phase angle of the target instead. But let me go on......the phase angle of the ground does not represent how "strong" the mineralization is. But it does tell us if the soil is more magnetic or less magnetic by providing us with numbers corresponding to the ground phase. For example, a small phase angle would be representative of highly magnetic soil, providing us with a low "ground phase" number. A larger phase angle would be representative of the less magnetic soil, providing us with a higher "ground phase" number. So in answer to your question, by lowering the number of the ground phase adjustment,(setting the Ground Balance) you are setting your detector to compensate for more "mineralization" (more magnetic ground conditions that produce a smaller phase angle). And by raising the number of your ground phase adjustment, you are setting your detector to compensate for less "mineralization" (less magnetic ground conditions that produce a larger phase angle).

With all that in mind, and since you brought it up, Barnacle Bill posted instructions on how you can use to determine the actual mineralization of your soil. It is a very useful tool for those interested in analyzing the mineralization of their ground. Here is the link to that post:

http://www.findmall.com/read.php?55,574329,574329#msg-574329

HH Randy

 

[wal.ellison]

Hi Randy
Perfect answer to my query, and explained in a way that's easy to understand. I'll check out Barnacle Bills post re; mineralisation as you suggest. Many thanks Randy
Wal

 

[David]

Excellent reply by Randy and problem solved for you. But I have an input about the X-Terra 70 if we are on the subect of mineralization. I have found 2 areas around here my XT-70 has real trouble and does not work at all with good numbers being false signals due to clay-high mineralization. If you hunt in low mineralization on black dirt and some types of sand-gravel-rocks then you are fine with the XT-70(5). But in much higher mineralization a T2 Ltd may be necessary to use instead.

 

[teviotlad]

m xterra 305 has a gb range to adjust manually, from 0 to 20. does this mean wet sand would be near 0 or nearer 20 or in the middle?. it doesnt have tracking so if you had to set it , what value would best on wet sand, 0 or 20 ?

 

[Joe Z]

If you hunt in low mineralization on black dirt and some types of sand-gravel-rocks then you are fine with the XT-70(5). But in much higher mineralization a T2 Ltd may be necessary to use instead.

Being new to all of this...... What is a "T2" as my mineralization is very high here in Arizona. My ground balance is constantly between 13-15 on auto adjust and using the stock 9" consentric MF coil I may need to go to either a 10" DD MF or the 10 X 5 DD HF Elliptical ...... can anybody make a recommendation for me which would be better? I hunt mostly trailheads where people walk out here... a few parks but mostly try to find old buildings out in the desert for whatever i can find.
Thanks,
Joe