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preventing copper specimens from oxidizing

Posted by Gary Parisi  
preventing copper specimens from oxidizing
March 09, 2012 06:12PM
There is a member of our mineral club that has copper specimens he is trying to keep from oxidizing. I gave him the article written by Evan M. Johnson. He does not want to coat his specimens with any polymers or such. I was giving this some thought, and came up with an idea I would like to run by Mindat members. What if you placed the specimen in a glass or plastic specimen container and then filled the container with carbon dioxide. CO2, being heavier than O2 would displace it. If you then seal the container, would this not work. Are there any reactions of copper to CO2. Thanks in advance.
avatar Re: preventing copper specimens from oxidizing
March 11, 2012 07:49AM
There should be no reaction with CO2 at all. Even nitrogen would work.

Rock Currier
Crystals not pistols.
Re: preventing copper specimens from oxidizing
March 11, 2012 01:49PM
    
Packaging in an inert atmosphere is something that is often done for very sensitive specimens, i.e. refined chemical elements. However, preventing long-term (micro-)leakage is not always a trivial issue.
EMJ
Re: preventing copper specimens from oxidizing
April 25, 2012 01:00PM
Maybe a thin coat of clear shelack might do the trick and can be easily dissolved off with methylated spirits.
avatar Re: preventing copper specimens from oxidizing
May 07, 2012 01:02AM
If you can find it, there is a powder that you mix with one gallon of water called CopperBrite. It is a mixture of chromium trioxide, sodium bisulfate and sodium bifluoride and does an excellent job of preserving a nice shiny finish on native copper for many years.
avatar Re: preventing copper specimens from oxidizing
May 26, 2012 04:25AM
    
Traces of water, together with carbon dioxide present, will inevitably lead to carbonate formation in the long run (although the process may proceed rather slowly). If there's an "oxygen sink" (i.e. an oxygen consumer in a system), there will be a concentration gradient along which oxygen is still transported. It should also be noted that accumulation of carbon dioxide at the bottom of a vessel is a short-term effect. In the long run, all gases present will homogeneously mix (principle of maximum entropy).
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