Halo matrix question ?

[smokedaddy]

I know that deep old coppers etc. can be pulled from great depths with the halo actually making the detector see a larger target. My question, is there any halo effect on old deep silver. I dig a lot of large coppers and brass down to 12-15" but I am slacking on the occasional silvers, unless they are large and shallow. My shallow in my area is 5-6" for silvers. I know that I am missing deeper silver targets and just want to hone the skill. (Mainly the halo question) Thanks Folks.

I use a M/L Soverign Elite and an XLT.

 

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[rcasi44]

Here is what Nasa Dan said in his article on ground moisture. Iron is a metal that can produce a very large oxidation halo. Copper coins can produce a fairly large halo, silver items a very small halo and pure gold produces no halo. Rob

 

[Charlie P. (NY)]

Some folks will tell you there's no such thing. Others swear by it. I believe there's something to it and suspect it has something to do with the galvanometric action of a coin, say, and the dissimilar metals and minerals in the soil actually causing some electric or corrosive action that puts an area around the coin that increases the coil's ability to detect the object. My version would also explain why wet soil allows deeper finds than dry (moisture increases the galvonometric effect). Also, a silver or gold coin would not "suffer" because it would be the iron, salts and lesser metals (less noble) in the adjacent soil that would. Remember from the periodic table that Sodium, Calcium and Potassium - the basis for most salts in the soil - are metals.

The "halo" is not molecules from the coin dissipating into the soil. It is the soil being effected by the presence of the coin; possibly in a purely catalytic reaction that does not change the coin at all.

And then there's whatever the heck they use at the town park. It will dissolve a post '82 cent into a mess that looks like a chewed on oatmeal cookie but the pre '82 cents are fine. Nitric acid in the fertilizer, maybe?

 

[Jim Hemmingway]

Hi Smokedaddy,

If we eliminate the word "halo" for the moment, and rephrase your question to read..." is there some phenomenon, that can cause old, deep silver coins (meaning buried in undisturbed ground for some lengthy period of time) to be more easily detected at greater depths than recently buried silver coins in (obviously) disturbed ground, the answer is yes.
The three main concepts seem to revolve around (a) leaching of the coins metallic constituents into the surrounding soil matrix, and, (b) alignment of electrical charges within the soil immediately adjacent to the coin. (c) increased eddy current formation on the target in undisturbed ground.

In undisturbed ground, electrical alignment remains unchanged, and may for that one reason alone, provide satisfactory explanation as to why we can locate silver coins deeper than in recently disturbed ground. Do we know this to be a fact in science? No, we don't.
With regard to leaching of the coins metallic constituents on a molecular level into the surrounding soil, factors including the soil type, acidity, chemical constituents (namely, corrosive fertilizers), and moisture content...can provide favourable (and frequently catalytic) environments for either oxidation or reduction reactions to occur between the soil and the coins molecular surface.
Coin hunters are well aware of the obvious copper oxides that form on the surface of copper pennies; and frequently see that same residue leached into the surrounding soil as well. Do we know this phenomenon enhances our ability to detect that type of target in scientific fact? No, we don't.

Elementary chemistry tells us that silver is a reactive substance, quite willing to change it's outer orbital electron profile to accomodate many different chemical bonds. The most common reaction is for silver to become reduced and consequently form the compound silver sulphide. In consistently wet substrates, or in anaerobic sediments in freshwater areas (I don't know about salt water environments at all), it not uncommon to retrieve older silver coins completely covered in black tarnish...silver sulphide. I have seen firsthand examples of silver coins reduced to paper thin metal due entirely to sulphide reduction reactions in anaerobic environments.

Also, keep in mind, that silver coins are normally alloyed with an even more reactive metal....copper; 10% in US silver usually (and don't forget about 10% in gold coins), and 10 to 20% in Canadian silver coins, depending on the mint date. I have seen, after digging several thousands of silver coins, some few from very dark organic soils at superb depths, that had not a patina, but rather a powdery crystalline coating of copper oxide on a part of the coins surface. I attribute both the extra depth and the copper oxide coating (blue-green) to the higher organic content soils (that contain increased amounts of organic acids)...providing even more favourable environs for chemical reactions.

The point is then, that silver coins and other various metals do react to form compounds that have no alternative but to leach into the surrounding soil. I doubt that this "halo" has anything to do with greater depths in undisturbed ground, but as you can see, it's easy to argue it's formation.

There is a third very plausible explanation for enhanced target depths and ID in undisturbed ground involving a theory wrt less of the EM field being absorbed by undisturbed vs disturbed ground, thus allowing for greater target eddy current formation and hence increased energy return to the coils receive winding. Makes more sense to me.

Whatever the reason, the "phenomenon" is substantiated by experience in the field, rather than on a scientifically measured basis, and can easily be demonstrated at any time by anybody. Dig a deep silver coin, rebury it, and try to redetect it. I consider that evidence to be unassailable. I stand to be corrected, but that's my current take on this subject.

 

[Sandman]

Great POST Jim! There is nothing I can add.

 

[Treasure_Hunter]

Very interesting read Jim, thanks...........

 

[U.K. Brian]

So you would all like a halo so you can detect a coin a little deeper ?

Doesn't matter that the coin is going to be a bit of scrap metal not worth recovering.
Doesn't matter that if you break open a lump of soil and remove say a copper coin thats left a perfect green impression no detector, even a gold machine with a small coil, will detect the "halo".
Doesn't matter that a halo can be switched on or off according to the amount of moister in the soil.
Doesn't matter that many coins produce a patina that in effect insulates the coin making detection harder.

If you have damp/acid soil it breaks down the coin, creates an electric current and the surface of the coin becomes rougher and therefore bigger to the currents passing over the surface. So it can be detected deeper. The less pure the metal the more the effect. But the coin or item is going to be in a shocking condition.
Iron breaks down rapidly and creates a large halo that creates major problems for a detectorist but P.I.'s are insensitive to this which is their major advantage as Reg has found out. Its not going to lead to parks being cleared of deeper coins though as you still suffer the effects that led to the surface blanking machines being phased out. Your not going to be finding anything below an item whether you hear that item or not.

The Compass Depth Doubler put a current through the ground and increased detection depth. Drawback was that depth was increased (and the target masking) most on iron, which was not what the average coinhunter wanted. It did however show the effect of an electric current on a buried item and thats exactly what you get as a coin breaks down. An electrical halo that won't form in neutral ground or if the soil is bone dry.

The "proof" of digging a silver coin then reburying it is more disturbed soil matrix than "halo". Bury a coin in a large plastic pipe for a few years, keep the soil damp, check the depth then allow to dry out. Where has the depth gone? The "halo" is still there.

The original problem of finding the deep silver is not due to halo or the lack of it as he's already detecting these coins. He just doesn't know it. Construct a test bed of a series of coins of the same type/date at varying depths. After several years use any of the major brand machines and all will detect a certain number of the coins depending on power of the machine, ability to be ground balanced, coil size etc but all have a depth where they will start to I.D. the coins as iron.
There's ways round this with some machines but it does mean all targets have to be heard which is hard work. On the other hand gold coins turn out to not be as had to detect as most think either so the effort is worth it.

 

[smokedaddy]

Thanks for your thoughts on this guys. If I am reading everyone correctly on this, the deep silvers may sound like iron or broken signals. When the target is out of the detectors depth range, even tone ID would be a false reading ? . To sum it up, all faint deep targets, just dig to china and hope to score.

 

[smokedaddy]

I forgot to add this on my last reply. What are you guys hearing when you get the extra deep silver signal. Is it a blip, solid ? If you are using tone ID, Are you getting the high pitch as in a shallow coin ? Sorry to be banging away here. The replies to this thread are very interesting and I thank you for the education. I am sure that there were as many silver coins lost as there were coppers, but it seems that in general,more coppers are being pulled from deep ground than silvers . Thanks Guys.

 

[ivan salis]

most machines even top notch ones have id "issues" beyond 6 to 8 inches of depth --(mainly due to the fact that they id the type of metal found by its conductivity --differant metals have differant conductive rates ---which is how the machines sort out which type of metal its "found" from the reaction of the electric feild it makes to the metal object ----minerals in the soil and overall depth of the soil (the machines feild gets weaker the farther is is from the machine) can throw this process off the deeper the object the less accurate the id will be a a general rule esp for coin sized objects and thus give false id's --deep silver often false id's or sounds like iron -- that why lots of old time detector folks are in the dig all deep signals camp --

and the reason for more copper coins being found than silver coins being found is two fold --one coppers easier to pick up on a metal basis (copper is an excellent conductor thus ir rings up easily to the detector) and two just like today there is more $1 bills out there than $20's out there --the copper coin was the dollar of old the silver the $20 -- thus in sheer numbers the coppers were more common --thus more likely to be lost than the silvers were. ---makes common sense huh?--- Ivan

 

[TORRERO]

My personal opinion is that Iron can have a "Halo" affect because it break down and rusts and eventually
would disintegrate all together if left long enough, and can leach into the soil.
But for the most part Silver and Copper does not. Copper might slightly over hundreds of years as we have all seen the green patina that forms...
That said, I have dug Hundreds of silver coins, from Roman Silver Denarius, to modern day silver
Roosevelt's, and all the silver I've have found normally comes out looking like the day it was dropped.
Even the Roman Silver.
Some Silver has come out with discoloration on the metal, but I believe its because of its location relative
to a piece of Iron or other item that stains the silver while buried.
In more than 20 years of hunting, no amount of talking will convince me differently.
Gold does not at all, like the man said.
You may get more depth when the soil is wet, but I think its due to the moisture in the ground.
My two cents...

 

[Fast Randy]

The gold nugget hunters i have talked to would mostly agree that nuggets also have "halo". I just found my first last Friday but the thought of burying it over at 16" never crossed my mind. Maybe next time.

 

[Ricardo_NY1]

There is no doubt beyond doubt in my mind, I will not even give it a name, halo, etc, etc,etc........that an undisturbed silver coin's signal is stronger and better in its undisturbed state. Once you remove a few inches of dirt that disturb the coin and soil below, the signal faints out or doesn't even sound like a silver coin anymore, as is the case with my machine. Perfect example this past Saturday......I get a nice and deep silver sound at at least 7 inches......probably closer to 8..........although faint, I could hear the silver sound..........once I dug that 5-6" plug.......you'd think there was a regular penny down there. And this happens ALL the time.
I'm talking about the Explorer. Back in the days when I used my ACE..........I could re-bury a freshly recovered silver dime down 3 inches and not a peep from the machine......which of course originally found the dime minutes ago deeper then that. I again will not attempt to label or explain the phenomenon, I just know that it exists and detect accordingly. I know that just because a signal is gone does not mean anything........I keep digging in the last place I remember pin-pointing it good or go into pin pointing modes to try to hear it there. I actually like it when I hear a good and deeper silver sound and loose it. This is the first indication that it's a silver dime deeper than normal and almost always works out that way.

 

[liquid1]

Great info folks..