# Reverse oxidation



## MH36 (Nov 5, 2021)

I am looking for advice on how to reverse the oxidation processes that silver (and possibly gold) may endure if say they're exposed for a prolonged and unknown amount of time to flowing water source where known sulfur well are abundant therefore the probability of higher sulfer levels in the creek is very likely...any other processes other than boiling water+baking soda+salt+aluminum foil method?


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## Lino1406 (Nov 6, 2021)

Cancelled


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## Lino1406 (Nov 6, 2021)

Al method is after action. A preventive method could be copper or lead presence, worth trying


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## Geo (Dec 24, 2021)

Silver and gold weathers very well in water. Abrasion by sand and grit breaks the metal down but there shouldn't be enough oxidative effects of ground water to dissolve either metal at normal atmospheric pressure and temperature range.


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## MH36 (Dec 24, 2021)

Geo said:


> Silver and gold weathers very well in water. Abrasion by sand and grit breaks the metal down but there shouldn't be enough oxidative effects of ground water to dissolve either metal at normal atmospheric pressure and temperature range.


Wouldn't the levels of sulfur in the ground and the water surrounding location have an impact on the speed of oxidation or what ever that silver goes through when exposed to higher levels of elements that oxidize it? Isnt sulfur like the biggest "enemy" (oxidizer) of silver? With sulfur and water combined wouldn't that hit silver with a stronger oxidizing effect? I apologize for the many questions in a row, my mind works very rapidly and it bothers people sometimes... i am just so curious about things that interest me and i want to learn what i can to satisfy this curiosity I've found with this situation! Thank you in advance!


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## MH36 (Dec 24, 2021)

A


MH36 said:


> Wouldn't the levels of sulfur in the ground and the water surrounding location have an impact on the speed of oxidation or what ever that silver goes through when exposed to higher levels of elements that oxidize it? Isnt sulfur like the biggest "enemy" (oxidizer) of silver? With sulfur and water combined wouldn't that hit silver with a stronger oxidizing effect? I apologize for the many questions in a row, my mind works very rapidly and it bothers people sometimes... i am just so curious about things that interest me and i want to learn what i can to satisfy this curiosity I've found with this situation! Thank you in advance!


Also what would the effects be if there were carbonaceous black shale that formed atop of the precious metals? Would that have any effect? What would be able to remove the brittle shale without harming the precious metals? I am determined to find answers to my many questions about my specimen....


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## Jado (Dec 24, 2021)

Silver can be de-tarnished by oxidation of either Hydrogen or Carbon. Neither process has too many limitations. I’m honestly not sure about gold, I’ve only ever heard of oxidation of gold in vague archeological articles.


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## Yggdrasil (Dec 24, 2021)

That is fine, but will that restore the item to its former glory.
I'm afraid that if oxidation has gone too far there will still be significant damage. If the techniques described above will restitute the silver in situ it may cause more damage then gently removing it.
I would contact an archeological institute and ask their advice prior to doing something that may cause more damage.
Since it has years in water, a few months/weeks in deionized water and darkness will not cause additional damage.

Regards Per-Ove


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## goldshark (Dec 25, 2021)

Silver does not oxidize, it sulphidises. Silver has an inherent ability to want to turn back to a silver sulphide, where it is most stable. In certain geological conditions, namely the presence of shale carbon layers, it is then precipitated back to native Silver. We believe this is what happened in the Molly Gibson Mine in Aspen, Co., which has produced the largest nugget of Silver to date, in the world. A little over 2000 lbs. Troy. Supergene Gold can be dissolved in leaching pyritic veins with the presence of Manganese dioxide. This produces a weak chlorine solution which is enough to dissolve fine gold included in the oxidizing pyrites. It is then precipitated out as either a coating on pyrite, or can also be precipitated on a fine piece of Fe. This usually occurs in the vadose zone.


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## orvi (Dec 25, 2021)

goldshark said:


> Silver does not oxidize, it sulphidises. Silver has an inherent ability to want to turn back to a silver sulphide, where it is most stable. In certain geological conditions, namely the presence of shale carbon layers, it is then precipitated back to native Silver. We believe this is what happened in the Molly Gibson Mine in Aspen, Co., which has produced the largest nugget of Silver to date, in the world. A little over 2000 lbs. Troy. Supergene Gold can be dissolved in leaching pyritic veins with the presence of Manganese dioxide. This produces a weak chlorine solution which is enough to dissolve fine gold included in the oxidizing pyrites. It is then precipitated out as either a coating on pyrite, or can also be precipitated on a fine piece of Fe. This usually occurs in the vadose zone.


Yes, it needs to be special enviroment and thousands of years of time to do something with it. But yes, silver is washed out more easily. Happen in many situations with placer gold - from the surface of gold, silver is leached by sulfurous stuff (many kinds of anions), leaving the more fine gold surface. Supergene gold is a good example, very specific, less known... Like one of the biggest pieces of gold I ever panned was from supergene deposit 
PS: sulphidization is also an oxidation reaction


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## orvi (Dec 25, 2021)

MH36 said:


> I am looking for advice on how to reverse the oxidation processes that silver (and possibly gold) may endure if say they're exposed for a prolonged and unknown amount of time to flowing water source where known sulfur well are abundant therefore the probability of higher sulfer levels in the creek is very likely...any other processes other than boiling water+baking soda+salt+aluminum foil method?


I dont think that anything major happened to the gold. Silver could be easily tarnished. Expert advice is needed if the thing is of great value to you. I will try just thiourea based silver cleaner - bought in store.


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## Geo (Dec 25, 2021)

If it is an object, there are redox methods used when recovering and preserving artifacts that were dug up or recovered from the ocean. Not just precious metals but objects made of other metals, like iron. These objects can be hundreds or thousands of years old and have been exposed to gasses in the atmosphere or the corrosiveness of sea water. 
Objects found in fresh water, like a river, are not exposed to the elements and it's corrosive effects. In rivers, the most major cause of tarnish is organics that are washed into the river. Of these, the one that I have studied about the most that effects all precious metal in native form is sap from trees. Sap is expelled from the leaves and needles of trees close to the river. The sap adheres to the precious metal, even tiny flakes, and makes recovery by standard gravity separation harder. Certain chemicals used to improve recovery actually hinders the process. Surfactants tends to make small gold particles float. Gold is hydrophobic itself and will tend to float if it is clean and breaks the surface of the water. The collective organics load (sap) makes the effect even worse. Roasting concentrates was a trick the old timers would use to clean the gold so that it would only float if it was exposed to the air during separation. Native gold that we find in the river may have been deposited into the river millions of years ago. 
Silver will tarnish in the atmosphere due to hydrogen sulfide gas in the atmosphere but it's only a few atoms deep due to passivation. It does not effect gold to any appreciable amount.


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## Jado (Dec 25, 2021)

goldshark said:


> Silver does not oxidize, it sulphidises. Silver has an inherent ability to want to turn back to a silver sulphide, where it is most stable. In certain geological conditions, namely the presence of shale carbon layers, it is then precipitated back to native Silver. We believe this is what happened in the Molly Gibson Mine in Aspen, Co., which has produced the largest nugget of Silver to date, in the world. A little over 2000 lbs. Troy. Supergene Gold can be dissolved in leaching pyritic veins with the presence of Manganese dioxide. This produces a weak chlorine solution which is enough to dissolve fine gold included in the oxidizing pyrites. It is then precipitated out as either a coating on pyrite, or can also be precipitated on a fine piece of Fe. This usually occurs in the vadose zone.


Silver does oxidize, it’s only incompatible with B, C, H, L, & Be. It’s not common due to a weak affinity, but it was the OP question & can form in high pH mid temp situations or when excessive aromatics are present (solvent scrubbers).


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## Geo (Dec 27, 2021)

Old silver smells. Bad. Try it yourself or look up the term "does old silver have a smell?". When silver tarnishes over time and turns black from exposure to the air, it is absorbing hydrogen sulfide and will smell like a sulfide.


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