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Mercury Colouring
Posted By: Mike Allen
Posted Date: Feb 04, 2009 (01:49 AM)
Message
Mercury staining is another bit of folk lore in the jade collecting world.
So called mercury staining on a piece of jade is not mercury unless you are looking at the bright red stuff known as cinnabar, which is mercury sulphide.
Dealers in the markets love to use this term to offer credibility to a piece, as we all know the ancients scattered mercury or its salts all over the grave.So mercury staining is a good sign of indirect provenance, isn't it? Mmmmmmmm!
Most of the dark brown, purpley brown colouring blamed on mercury is actually iron staining, or alteration of the iron in the nephrite (actinolite/tremolite).May be if mercury was ever in the vicinity of the buried object, it is such a biocide, that it stopped the normal oxidative process of decay and changed it to an anaerobic environment.This may have affected the type of iron salts present, giving the darker colouring.
Cinnabar is red, if it is cinnabar and not poster paint or similar.Cinnabar is relatively inert so will not dissolve in water, or acetone like poster paint or acrylic paint.(A good reason to wash your jade pieces, you get to see all the details the faker was trying to disguise with dirt!)
Cinnabar will only change to the darker purple brown coloured metacinnabar at 345 degrees celsius.So if any one disputes the colour of your jade piece, and says it is not iron but metacinnabar, ask them to hold it. If it is metacinnabar, they should burn their hand.
So claims about mercury staining and it is not bright red, then the likely hood is that it is only iron staining of one form or another.
Mercury staining can be confined to the same cupboard as,"It is the only piece found like this" and "Its been in the family generations" or similar.
Happy hunting
Mike






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