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About the Halo
- Thread starter AK in KY
- Start date
MY POST IS PURE OPINIONS ON MY PART WITH THIS ONE. I don't think silver or gold will leach into the soil due to the stability of the metal. I have read explanations by several detector manufactures so I guess we can take this with a grain of salt.
I believe it is correct to say that the halo cannot support current flow. What makes sense to me to some extent is the halo is a condition of the soil that connects the target to minerals that are in contact with the target. The target is conductive and has different ferrous content and is bonded to iron minerals and salts in the soil. The target looks like an allow of the target and soil minerals which might be some kind of semiconductor.
Many people I have talked to or read their post say there is no Halo while others swear there is. I think there is and it is the bonding of the target to the iron minerals and salts in the soil which causes the target to appear to be an alloy.
In my opinion damp or wet metal will conduct surface current better due to salts in the soil which may account for more depth in damp soil. I have been told that if a site has a lot of iron and we are looking for relics to go after it rains and the soil is damp. On the other hand if looking for coins in a lot of iron then go when it is dry as the iron is not as conductive. I have read this a number of times by relic hunters and in a book or two somewhere. It would appear to me that dry soil is not going to "conduct" the electromagnetic field since the soil is something like a pile of rubble. I have no way to really test these ideas which is why I said at the start that these are pure opinion on my part.
I believe it is correct to say that the halo cannot support current flow. What makes sense to me to some extent is the halo is a condition of the soil that connects the target to minerals that are in contact with the target. The target is conductive and has different ferrous content and is bonded to iron minerals and salts in the soil. The target looks like an allow of the target and soil minerals which might be some kind of semiconductor.
Many people I have talked to or read their post say there is no Halo while others swear there is. I think there is and it is the bonding of the target to the iron minerals and salts in the soil which causes the target to appear to be an alloy.
In my opinion damp or wet metal will conduct surface current better due to salts in the soil which may account for more depth in damp soil. I have been told that if a site has a lot of iron and we are looking for relics to go after it rains and the soil is damp. On the other hand if looking for coins in a lot of iron then go when it is dry as the iron is not as conductive. I have read this a number of times by relic hunters and in a book or two somewhere. It would appear to me that dry soil is not going to "conduct" the electromagnetic field since the soil is something like a pile of rubble. I have no way to really test these ideas which is why I said at the start that these are pure opinion on my part.
I have heard of a little different version of the Halo effect,goes like this,foreign partical gets into the body,defence-system tries to encase it,may cause some swelling.So if a coin or non-ferrous item gets into the earth and cannot be broken down,then the minerals surrounding the foreign item it cannot eat away at, slowly tries to take on the simular characture of the non-ferrous metal which grows over the years.Think about it.HH,Rick.
Something happens that will cause a target to be detected deeper over time unless the target sinks out of detection range. I have read some pretty good explanation by engineers and wish now I knew exactly where and they say there is a halo. I think the bottom line is it helps to find coins and other traget deeper so that works for me.
Have a great day,
Have a great day,
Jim upstate NY
New member
The way I usnderstand it is, the minerals in the ground act as sort of an electrolite, which attracts the metal from the coin slowly away from it.. remember even though silver and gold are pretty stable metals, the copper they are alloyed with is not, and that copper will eventually create a halo.. it may take longer on gold and silver, but it will happen, wet ground increases the transmition on the current of the rf signals the detector sends, so yea it makes it easier to pick up bith metal and any halo that maye have foremed around it.. I think that ground comapction has a lot to do wit it too... at least for the minelabs multi frequency.. the more compact the ground the easier the rf signals travel through it
Bill_in_MA
New member
Here's some comments from the Fisher and Troy sites that may relate......
Fisher
The length of time an object is buried: Various chemicals in the soil have a corrosive action on metal. Some metals corrode faster than others. A modern zinc penny is attacked by these soil chemicals quite easily, whereas the action on copper and silver is much less, and corrosive action on gold is hardly noticeable, if at all. As these chemicals eat away at the metal, oxidation (rust) takes place, which is absorbed into the surrounding soil. This causes the soil to become more conductive, which in turn makes the metallic object appear larger than it actually is and easier to detect. This is known as the "halo effect."
Troy
......a good opportunity to explain how an open hole in the ground can effect the inductance pattern of a metal detector. By dropping the target back into the hole you just dug without covering the target with the plug and packing it down tightly, this causes a huge disruption to the search coil inductance pattern and makes it very difficult to detect the target at the bottom of the hole. Many people refer to this as disturbing the halo effect, but I have found that it is more of a case of disturbing the coil inductance pattern. If you would have covered the target with the plug or soil and NOT packed it down tightly, you would have had the same results as not covering the hole. BUT, if you had covered the hole and packed it tightly, then you would have seen completely different results. You would have been able to raise your coil much higher above the target while testing this target. This is the reason it is very important to continue to "dig" when a good signal disappears while digging. In most cases the target is still in the hole, it is just deeper than you may think it is. Many good targets are not recovered because of this reason.
Fisher
The length of time an object is buried: Various chemicals in the soil have a corrosive action on metal. Some metals corrode faster than others. A modern zinc penny is attacked by these soil chemicals quite easily, whereas the action on copper and silver is much less, and corrosive action on gold is hardly noticeable, if at all. As these chemicals eat away at the metal, oxidation (rust) takes place, which is absorbed into the surrounding soil. This causes the soil to become more conductive, which in turn makes the metallic object appear larger than it actually is and easier to detect. This is known as the "halo effect."
Troy
......a good opportunity to explain how an open hole in the ground can effect the inductance pattern of a metal detector. By dropping the target back into the hole you just dug without covering the target with the plug and packing it down tightly, this causes a huge disruption to the search coil inductance pattern and makes it very difficult to detect the target at the bottom of the hole. Many people refer to this as disturbing the halo effect, but I have found that it is more of a case of disturbing the coil inductance pattern. If you would have covered the target with the plug or soil and NOT packed it down tightly, you would have had the same results as not covering the hole. BUT, if you had covered the hole and packed it tightly, then you would have seen completely different results. You would have been able to raise your coil much higher above the target while testing this target. This is the reason it is very important to continue to "dig" when a good signal disappears while digging. In most cases the target is still in the hole, it is just deeper than you may think it is. Many good targets are not recovered because of this reason.
Bill_in_MA
New member
That copper can certainly leach from ancient gold coins has definitely been shown to do so - at least on ancient Celtic gold coins. Some of these coins consist of a Au-Ag-Cu alloy, in which the silver and copper contents can be as high as 20%. Leaching effects from the long time burial of the coins in the soil matrix can lead to a depletion of the less noble metals silver and copper from the coin surface. Thus interestingly enough the coin's surface can actually end up with a higher gold content than the original starting blank material. If it can do so on coins with this composition then likewise I'm sure given time and the right soil conditions leaching will occur.
I had read the post by Fisher and talked to Troy about a year or so ago and have great respect for his detectors. The longer a target is in the soil the deeper it can be detected is something I strongly believe. It is from over 40 years of detecting with many different machines. As they say even a blind hog will find an acorn once in a while. Somewhere in those first few years the light turned on and it seemed clear to me that a dime that had been in the soil for a hundred years could be detected and had a sound like a newer quarter at much less depth. We did not have discriminators or a VLF or the internet so it took a little while for me to realize that. I really have not paid much attention to this in the last several years with the VLF, Audio Boost, and all that technology and depth. I assume there is a halo and that is a contributing factor in depth of detection and am happy thinking it is true. I guess I will go on thinking it is true even if an engineer proved to me I am completely wrong. I want to think there is a halo and as long as I find deeper coins for that reason then why break my bubble and then I don't get as much depth knowing there is no halo. Ha ha
Bill_in_MA
New member
Far be it for me to burst your bubble - I believe in the Halo Gospel according to Cody all chapters and verses.
I don't know the answer whether there is a halo effect or not(even though I believe in it) but one point I think all can agree on is soil matrix. If you plant a coin by digging out a hole and then cover it over at the limit of detection range then one can expect his detector to at least be able to detect a like object in the field and even deeper given no other variables are introduced. When a coin is planted the ground matrix is rearranged so it is harder to detect. Thus a planted coin garden can give a general idea to how a detector responds in one's local.
Steve(MS)
Steve(MS)
migolddigger
New member
I was reading this post and I thought I would add my 2 cents worth. I believe in what Cody is saying about the halo effect. Heres why. If you ever dig up a target let's say a An old penny, say a flying eagle He- He-, And that green patina is all around it and in the soil. Try detecting that green soil. It doesn't register at all, does it? That's your Halo answer right there. I believe in the scientific approach on this. Wet ground + current = better penetration and signal reaction. Thats it. This is Just my opinion though so don't bite my head off.
Tom
Tom