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BLUE PATINA

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Julian_II:
An experienced well known numismatic here in Argentina, told me an interesting thing about the blue patina. One of the few ways if there are any else, of developing this patina is when the coin was left inside the mouth of a dead body, this starts the process that will generate the blue patina.
Very interesting, isn`t it. :)

bruce61813:
The blue is Azurite. For a real heay duty explaination of this type of corrosion on coins see: http://aic.stanford.edu/jaic/articles/jaic31-03-007.html
A short form of this articles is" "Azurite indicates that the artifact corroded in the presence of elevated carbonate activity. Microbiological decomposition of organic material is one source of elevated carbonates."
 See also http://aic.stanford.edu/jaic/articles/jaic21-01-001.html
A decaying body would produce a lot of CO2, and little exposeure to water or air.

BOTMN

Robert_Brenchley:
Azurite is a copper carbonate, so this wouldn't be surprising.

Rugser:
The reported one from the Argentinian friend is a fable.

The 90%  of our coins they have stayed in mouth to the corpse ... have we the 90% of blue patina?
The truth is that the patina of the coins is the result of a strange combination.

1)Composition of the alloy.

2) Components of the contained salts in the ground (each ground has his salinity)

3) Degree of damp of the ground.

It is try the fact that terrestrial  in same  two equal coins give to the corpse they engage colour of different patina.....as tells is my experience.

ser

Julian_II:
As said before this is something a friend told me. I don`t stand in any position with so little information yet :)

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