Ground Probe

[steve herschbach]

Hi,

People think a ground balance setting tells you something about how much ground mineralization there is. This is not quite correct.

A GB setting takes into account the TYPE of ground mineralization, not the AMOUNT. I know of only three machines that can reveal a true ground reading.

The White's GMT and Fisher F75 have this ability with a direct reading - thanks Dave.

The White's DFX can do it in a convoluted fashion that I do not remember.

There may be others I am not aware of.

The Vision has the Ground Probe -

From the DRAFT MANUAL:

Ground Probe (Ground Tracking Zoomed).

Ground Probe - From the LIVE CONTROLS, when Ground Tracking is
highlighted, pressing ZOOM accesses the standard MENU with a
Ground Probe on right side of display. Menu/Tab to Zero with search
coil held in air away from all metals and ground minerals. At this point
the search coil can be lowered to the ground, a target, or a target in
the ground, and measurements of significant data are displayed within
the Ground Probe portion of the display.

1. The Phase in a normalized VDI number format of what the search
coil senses is displayed.

2. The phase angle in degree

 

[Jason in TN]

Hi,

People think a ground balance setting tells you something about how much ground mineralization there is. This is not quite correct.

A GB setting takes into account the TYPE of ground mineralization, not the AMOUNT. I know of only three machines that can reveal a true ground reading.

The White's GMT and Fisher F75 have this ability with a direct reading - thanks Dave.

The White's DFX can do it in a convoluted fashion that I do not remember.

There may be others I am not aware of.

The Vision has the Ground Probe -

From the DRAFT MANUAL:

Ground Probe (Ground Tracking Zoomed).

Ground Probe - From the LIVE CONTROLS, when Ground Tracking is
highlighted, pressing ZOOM accesses the standard MENU with a
Ground Probe on right side of display. Menu/Tab to Zero with search
coil held in air away from all metals and ground minerals. At this point
the search coil can be lowered to the ground, a target, or a target in
the ground, and measurements of significant data are displayed within
the Ground Probe portion of the display.

1. The Phase in a normalized VDI number format of what the search
coil senses is displayed.

2. The phase angle in degree

 

[Carolina Phil]

You posted that the White's Vision, White's GMT, White's DFX and Fisher F75 are the only machines that you know of, which can give a true mineralisation reading. I will add to that list the White's MXT. I can also add the Minelab X-Terra 70, by a procedure which is not in the manual, but is described here. Their could be others also, which I am not aware of.

 

[steve herschbach]

Hi,

My MXT has a ground balance reading but no "mineral amount" reading that I am aware of. Where are you seeing it?

Steve Herschbach

 

[Larry (IL)]

I think you have to use Jeff Fosters formula from his book on the MXT to calculate the mineralization Steve.

 

[Carolina Phil]

I've never owned an MXT, so I'm certainly not an expert on it, but I have read Monte's posts in the past and from what I understand from him, the ground phase reading (GND) in the prospecting mode is a fairly accurate reading of the ground. I searched here on FindMall Forums and found a couple of those posts that Monte has made concerning this. (I hope Monte don't mind.)

http://www.findmall.com/read.php?25,396748,397267

http://www.findmall.com/read.php?31,882544,882609


Below is a section about GND from page 13 of the MXT online manual that I cut and pasted. (I hope White's don't mind.)


3. GND - Indicates the phase (measurement) of the ground. This is useful in two different environments.

A. Within a dry wash the gold will settle with the heavier materials (black sands). When searching you notice the ground phase is declining (lowering in number), generally you are working further away from the heavy black sand deposits. If you notice the ground phase is increasing, generally you are working toward (closer) to the heavier deposits. By following the more intense ground phase you increase your likelihood of finding nuggets.

B. Checking outcropping or veins, the ground phase can also be useful in a similar way by indicating the consistency or change of the veins ground phase.

Generally speaking, the ground numbers will hold fairly consistent in most open terrain areas, such as hydraulic sites and desert areas. GND readings in the high 70's and 80's are considered heavy iron mineralization. Alkali or salt areas will display much lower numbers, possibly into the 30's and 40's.

Ground phase indications are a doubled edged sword. Higher numbers simply mean predominately ferrous (iron) such as black sands / magnetite. Lower numbers simply mean less iron and/or predominately conductive nonferrous (not of iron) content, such as gold per ton of rock. So in a dry wash, outcropping, or vein, a shift in either direction (higher or lower numbers) may be of interest. For example a black sand streak may have a lot of flour gold at one end. It will indicate a high ground phase number on the end without the flour gold, and a lower ground phase on the end with the flour gold. The same applies to veins or an outcropping. It is the change that brings about the interest more so than if it is either high iron (high number) or high conductive (lower numbers). Knowing that the ground is high iron (magnetite), outlining black sand pockets, and checking veins for consistency (change), and comparing rock samples for possible assay, are the common uses of ground phase. Again, change is of the most interesting, not direction.

 

[Lowjiber]

I'm finally getting time to take my Vision out for the first time this morning and was reviewing the expert manual (draft) regarding the Ground Probe.

What does the term: "Menu/Tab to Zero" mean? I don't see a "Zero" on the screen. Is this intended to just let the detector "find it's space" before placing the coil on the ground?

(Perhaps in the field I'll realize this is a dumb question...but gotta ask.)

Thanks much,

John

 

[ak_1234]

When you zoom the tracking live control, you will get a display with options - track settings on the left, phase information on the right, and two control selections on the bottom - zero and exit. When you press the menu/tab button, you will be on the zero control. With the loop in the air, press enter (zero). You will see the phase info on the right show random phases - nothing to worry about. When you lower the loop to the ground, you will see the ground phase.

If we did an air/ground balance like on the DFX, we wouldn't need to have the zero option, but the V starts up with fast tracking enabled, so theoretically you don't need to ground balance. It has been found to work a bit better with doing the operator controlled fast track, but it is not required necessarily. But since we don't get the air reading, we have to zero in the ground probe.