Mercury coated gold

Bonaro

Hero Member
Aug 9, 2004
977
2,213
Olympia WA
Detector(s) used
Minelab Xterra 70, Minelab SD 2200d, 2.5", 3", 4"and several Keene 5" production dredges, Knelson Centrifuge, Gold screw automatic panner
Primary Interest:
Prospecting
The area where I dredge has a LOT of mercury. Almost all the gold is coated and it's not uncommon to find puddles of HG in the sluice. To remove the HG from the gold I use a nitric acid bath to dissolve it. This works well but the gold left behind is always dull and low lustre.

Nitric alone should not etch the gold. I have a theory that the mercury, after being in contact with the gold for many many years, actually begins to soak into the surface of the gold. Then when its removed, the surface of the gold is left rough and dull.

Regardless of why it happens, the gold is dull and unattractive after removing the HG. Soaking in vinegar and salt doesn't seem to help and the only way I have found to brighten and shine to gold is to tumble it with mild abrasive....time consuming

What is going on and how do I fix it? :icon_scratch:

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KevinInColorado

Gold Member
Jan 9, 2012
7,037
11,370
Summit County, Colorado
Detector(s) used
Grizzly Goldtrap Explorer & Motherlode, Gold Cube with trommel or Banker on top, Angus Mackirk Expedition, Gold-n-Sand Xtream Hand pump
Primary Interest:
Prospecting
Museum quality gold sponge!
 

calnatv

Full Member
Mar 19, 2011
143
215
Ammonia. Either in a rock tumbler like HJ said or in a plastic jar\vial and give it a shake every now and then
 

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