Hi FrancoItaly,
The phenomenon has never been defined.
We have heard many stories of how long time buried metal things can have a halo from people who use metal detectors. Then after digging the metal things, the halo is gone.
Is the halo a phenomenon? I think so. If it is not a phenomenon, then hundreds of metal detectorists are all wrong when they report they got a really strong signal from a simple coin, and the strong signal became normal after digging it. Even I have seen this halo effect on non-ferrous metal objects on a few occasions.
But halo seen when using a metal detector to find a coin is only one property of "phenomenon".
We also hear many other reports of different "phenomenon" properties.
For example I have read these explanations of what happens to long time buried metal
...
Some descriptions of the long time buried metal phenomenon told in the Geotech forums:
1. The buried metal releases ions into the ground
2. The buried metal releases ions into the air that can be measured with ion detectors
3. The buried metal becomes a ground battery that can be detected with resistivity or current sensing ground probes.
4. The buried metal vibrates mechanically and can be detected with acoustic equipment.
5. The buried metal sends out EM waves that can be detected with a receiver.
6. The buried metal will vibrate if an oscillator is set to send the correct AF or ELF frequency for the kind of metal that is buried. This vibration can be detected in a receiver.
7. The buried metal will show its location if you shine an IR LED on the ground above it with a chopper circuit. The location can be determined by watching for a change in the chopper circuit sending the LED power.
8. The buried metal will cause a change in the electrostatic properties of the air above where it is buried that can be detected with an electrostatic detector.
9. The buried metal will send out signal lines that can be picked up by any equipment capable of detecting signal lines.
10. The buried metal will wait for a carrier signal line to be shot to it, then the metal will return the carrier signal line where it can be detected by the LRL user.
11. The buried metal will make its location known biologically to all conscious animals in the area (in a radionic kind of way). For those not in tune to their inner selves, they may not be able to sense the location. But others will be able to sense the location from long distance, using only a map and a thread and needle.
There are more descriptions of what the "phenomenon" is, but nobody has defined it as a single consistent phenomenon that can be explained in a way that is understandable, and which has not been proven to be impossible. We get conflicting descriptions from people who believe the "phenomenon" exists. And we also get conflicting information from people who believe it does not exist.... ie: Metal detectorists such as Max who say LRLs and "phenomenon" are BS, also say they are sure halo is real. Isn't halo also an unexplained "phenomenon" we see from long time buried metal?
If "phenomenon" simply means unusual phenomenon that happens when metal is buried a long time, then halo is "the phenomenon" same as buried metals releasing ions is "the phenomenon". In fact any thing a person wanted to make up could be "the phenomenon", such as "a cloud of gold ions floats in the air above buried gold"... whether it is true or not. In order to determine what the "phenomenon" is, we must first consider which of the "phenomenon" descriptions we have been reading about are true, and which are false, tricks of the mind, or made up theories. If the phenomenon described is real, then it can be reliably detected repeatably by different people in different places in the world, not only in the Mineoro demonstration yard and by friends of people who work at the Mineoro factory.
Best wishes,
J_P