Quote:
Originally Posted by J_Player
Hi Esteban,
Sam asked several questions. He started by describing a phenomenon which most metal detectorists call "halo" effect that happens on rare occasions when they find old buried coins or other metals. Then he stated he understood how most common metals could corrode to produce some chemical action in the soil over a period of time. He was asking if anyone had verifiable information on how noble metals like gold could produce a similar effect when he asked a number of questions.
Here is his quote that explains his questions:
I have detailed all the answers to Sam's questions in many previous post I made showing how scientists observed even nobel metals corroding and metal ions migrating upward to the surface of the soil. I made many posts explaining how soil conductivity is influenced by the presence of the metal ions and other chemical activity, as well as how the soil moisture plays a part in drawing the metal ions up through capillary action caused by the rain cycles.
But I never did post anything about the influence of the sun. The sun's influence is seen mostly at the surface of the soil and maybe up to 30 cm deep. This is where the migrating metal ions see a thermal anomaly that is not seen at lower depths. If you recall, the scientists who measured the migration of the metal ions also observed that these ions were no longer ions when they arrived at a depth between 10 to 30 cm below the surface. The metal ions become bound with other constituents of the soil at this depth, to become salts or other compounds that are not ions. After the metal ions are bound as compounds, they may eventually be moved laterally by mechanical forces such as erosion or other means.
But what part does the sun play in this? I cannot give a scientifically proven answer, but, from what we know about the sun, it produces heat in the top layers of the soil, and it puts UV rays on the surface which are capable of making molecular changes to substances that it strikes. My thinking is the UV modified molecules on the surface are carried down during rain cycles maybe 10-30cm below the surface where they combine with some of the ions which have been drawn up during the soil-drying process.
For most non-noble metals, there are soil constituents that can combine to form salts. But for gold, the known chemicals that dissolved it are cyanide and sulfur complexes from organic acids that were produced by bacteria. The gold ions are suspended in these sulfur complexes until they reach close to the surface, where I would speculate that the sulfur complex breaks down and combines with other organic materials that have had their molecules re-arranged by solar UV, and leached into the soil. As these sulfur complexes are broken down and re-combined as salts near the surface, the gold ions are released as free ions, which will combine most readily with other gold ions, to form a gold lattice, or a tiny grain of micro-gold. This tiny micro-gold grain may eventually combine with other gold ions to become a tiny visible gold particle or not. But once it is stable, it is no longer an ion, and may mix into the soil where it stays, or where it may be eroded away.
This mechanism is only my guess. I have not found time to research scientific backing for this. But if it happens to be correct, then it also implies that there is an anomaly near the surface where the sun is active, and is indirectly causing the metal ions to become salts or other molecules. The anomaly I am talking about is the process of metal ions combining with other ions to form a compound. This anomaly happens at the top of the column of migrating metal ions when they become molecules, not to the sides of the column. The action of an ion joining another ion to become a molecule involves a microscopic transfer of energy. Don't know what this means, but it is a fact observed in basic chemistry classes.
Best wishes,
J_P
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Sometimes I found coins and other objects over the sand, but in hot climate. These metal are "cooking" in the surface, so appears a kind of "emission" because detection is very easy. These metal in the surface present the "phenomenon" or other "phenomenon" unexplained. But pistol detect very well it, sometimes better than other buried for long time.
Now regarding metals buried for long time, the via in wich the Sun helps is similar to the IR beam, I think. The "phenomenon" appears use the infinite rays of Sun as a "way" in wich "travel" the phenomenon, is a "bridge". This I think and I'm almost sure about it.
I built a spiral coil exposed, this is isn't enclosure. Well, with good light of Sun, directly over me and pistol I obtain many times extremely consistent and good signals, no intermitent, in sites with good conductive metals. Now, for the science, how a nude coil can be more sensitive when Sun light is present? The continuous detection only occurs in a critic point 1.40-1.50 m. If you move back or forward beeps are intermitent, but in critic point (not very) has continuity. Appears as a "resonance" point.
OK, during these experiment (I and a friend who saw it) dissapears the detection. What happens? A cloud passed for the place and concealed the Sun. When returned the direct beams of the Sun the detection continued! Other cloud. Detection stops. And when direct beams returned, detection continued.
Regards