[georgeos]

So I have some mercury in a small glass vial. It's a tiny amount, a small ball of it, about 4 grams. And I got it yesterday. Overnight it seems to have developed a gold coating around it. I played around with it a little, not touching it in case this gold coating was toxic. Could it be mercury oxide? Is mercury known to react with the air without ignition?

[MERCK86]

Mercury (ll) oxide is orange, not gold

[vmelkon]

Take a sample and drop some HNO3 (if you have). If the solution turns blue, then it is copper.
However, I don't have much experience with mercury alloys (except for Hg+Pb) and I would not know why it would form a ring.

[ccirrocc]

Hey

I am a gold prospector.  Gold will not coat mercury.  Mercury coats gold.  Gold is attracted to mercury like a magnet, sort of, in that if mercury comes in contact with gold, the mercury will coat the gold.  If to much gold is in the mercury it will look dull, kind of like lead.  This is why prospectors throw nithing out that is in their pan.  It is common in a lot of rivers where gold is found.  In the pan it looks like a silver flake.

cc

[Borek]

Gold will not coat mercury.  Mercury coats gold.

That's how it looks, but what is really happening is that mercury dissolves gold. Exact effect and the final look depends on the ratio of both metals in the alloy. And they are not attracted to each other, but when they meet mercury wets the gold surface and that's what hold them together.

[curiouscat]

Post a photo! 

[ccirrocc]

Thanks Borek.  When it comes to gold and mercury you can not have to much info.