Mineralzation

[archer]

At what point do you consider soil to be highly mineralized?

 

[B.T]

Tough one to answer sort of. Some areas have high mineralisation but it is of a "blanket" type where its say high in iron type minerals but is like that in every direction you walk in and after you balance in you may not need to for most of that area for some time. And even though its highly concentrated in those minerals it doesnt present a problem.
Then others have the type that changes from positive to negative in just a few steps and in extreme cases, like where I live, within inches. Here you need to rebalance and stay on top of it constantly to be in the game.
Here in Oz we call an area highly mineralised where we are in need of that constant rebalance, where it goes from positive to negative every step you take. Others would say its so when the mineralisation causes you to ground balance from one extreme to the other when they go from one area to another with a high variation on the scale from the last place they detected.
Clear as mud

 

[Digger]

The GB numbers on the X-Terra do not represent the mineralization of a site. They are called Ground Phase numbers and represent how conductive or magnetic (or both) your ground is. Although they do not represent the amount of mineralization in your ground, you will find that ground balancing at sites with higher mineralization will provide lower Ground Phase numbers. The lowest number I've heard of was a 4. I would consider that to be VERY highly mineralized. By the way, this was from a guy hunting in a mix of red clay and iron ore. I consider my soil to be moderately mineralized with Ground Phase numbers generally in the upper 20's to low 40's. Apparently White's considers my ground to be moderate as well. According to the VDI on my old MXT, my reading of 55 is moderate. (the MXT has a feature that allows the user to easily read the ground phase in the Prospecting mode. If your number is 30 to 50, you have low mineralization. Readings of 50 to 69 are found in moderately mineralized soil. A reading of 70 or over is highly mineralized soil.)

BarnacleBill made a very interesting post several months ago, explaining how to obtain a fairly accurage assesment of ground conditions by using an X-Terra 70. I am unable to find that post, to provide a link. But I had copied it and saved it in my notebook. Here is BarnacleBills report:

One of the ongoing common misconceptions is that the Ground Phase Number(Ground Balance)represents how much mineralization a particular soil matrix contains. The mineralization of course referring to minerals that cause poorer performance of a metal detector, and not a particular quantity of an inert material.

The Minelab X-Terra X-70 has a hidden feature which allows you to make a reasonably accurate assessment of your ground conditions including the iron(Fe3O4, black sand) and/or the conductivity(salinity) of your soil. To clarify, you can quickly measure in relative terms how magnetic or conductive your ground is. You can then jot those numbers down and compare them to any other X70 users in the world.

As a matter of fact a database or registry could be set up to compare your conditions to that of others. Therefore when an X70 user states that they have "high mineralization" which is hampering operation, it can easily be verified whether such is the case.

The procedure is really just an extension of Auto-GBing the X70. So don't become overly concerned that it is terribly complicated, it isn't.

Procedure in Normal GB mode with GB Tracking "OFF" and Sens=20:

A. Auto-noise cancel in the area you will hunting with the coil held 3 feet above the ground and parallel to it.

B. Locate a target free area of soil.

C. Engage Normal GB & remain in the GB screen.

D. Place coil on the soil. Do not press the coil against the ground! This will distort the coil shape and give an inaccurate result. Simply allow the weight of the machine to lightly keep it against the ground.

E. Press the Auto GB button and raise coil about two feet above the ground before Auto GB has completed. If by the time you reach the apex of pulling the coil up to two feet it doesn't complete, then pump up and down from just above the ground to two feet high as accurately as possible. Recall that Auto GB signals with a tone when completed.

F. While still in GB mode press and hold Patterns button to get the numbers. The numbers are six digits in length but read out in three groups of two that will repeat if the Patterns button is held down. Therefore 99 99 99(almost a million) is the largest number possible and 0(00 00 00) is the smallest. Forty-six thousand would appear as the following sequence, 04--60--00. Make a note of the numbers which we will call the "IRON NUMBER"(Magnetite...Black-Sand).

G. As a reference, numbers in the thousands are mild ground, medium grounds tens of thousands , and hot hundreds of thousands. For clarity:

1. 0(zero) >> 10K mild ground.
2. 10K >> 100K medium ground.
3. 100K >> 1M hot to scorching.

Procedure in Beach GB mode with GB Tracking "OFF":

The same as above in normal GB except that your are measuring conductivity. Great for Ocean beaches, salt flats, & dried up lake beds etc. I would also take three samples in the exact same spot and average them to get an average number, using either of the above procedures.

If their is enough interest, then a registry could be started to compare the various ground reports with how stable the detector runs, and effect on depth, correct ID etc. The nine inch default concentric MF should be the only coil used to take the measurements to create a standard. Keep in mind that the X70 may be able to show you why other detectors you own behave in a certain manner based on soil mineralization. It may also provide pertinent information about what equipment you should consider for future purchases.


Thanks for letting me share your post again Bill! HH Randy