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Originally Posted by J_Player
As far as a special field around buried gold, there is a lot of evidence from conventional detectorists to support this. Many detectorists talk about a "halo" around old coins and gold they find. They say they get a really strong signal on their metal detector, as if the coin is much bigger than what they actually dig up. But after digging up the coin, it then gives a normal signal, even if they bury it again.
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These are anecdotal stories, and have not been backed up either in experiments or in theory. Oxidized iron can definitely produce a larger response under certain conditions, but copper or silver oxides probably do not. I've read on other forums where a couple of people have tried to experimentally verify halos, and have failed. I suspect halos are mostly a myth.
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The explanation I heard is these coins develop oxides and other salts around them after they are in the ground for a long time. Apparently it takes a lot longer for gold because it more inert than silver, copper and other metals used in coins and jewelry. But even gold does form a very thin film of oxides and other salts after it has been in the ground long enough (most gold has a certain amount of copper or silver alloyed that will also corrode slightly at the surface and leach into the soil over time).
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Gold does not produce oxides, at all. Metals (copper, silver, etc) alloyed with gold will corrode, but not the gold.
- Carl