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Raw Gold, with Mercury?


#1

My cousin in Alaska has a sterling ring with raw chunks of
green gold soldered into it. Will this gold have mercury in
it? Is all gold mined with mercury? Do I need to ask the
miners. I don’t want to melt it down to use it, I want to use
the chunks pretty much as is. What do I need to know to
do this safely?

Good questions. To my knowledge:

  1. Not all good is retrieved with mercury. As a matter of fact, I think
    mercury “leaching” is illegal and rarely done anymore. It is an
    interesting process, though, whereby gold is recovered by pouring mercury
    over it, often in river beds. The gold “melts” into the mercury which then
    carries it further downhill. Then the gold-bearing mix is heated to
    evaporate the mercury, leaving the gold behind.

  2. Gold and Mercury do not form alloys. They form an amalgum at room
    temperature, or if heated in the proper proportions they form a very pretty and
    incredibly hard purple “rock” which is an intermetallic compound.

  3. Don’t bother to ask miners. I think it was Mark Twain who defined a
    gold miner as, “A liar standing over a hole in the ground.”

  4. Green gold is the color of gold alloys that have mostly silver
    and little or no copper in the mix. Each region on Earth has its own
    particular alloy of native gold (gold found in nature), with its own individual
    color, contents and other characteristics. An expert can identify the
    source by visual examination of native gold.

  5. Treat the green gold nuggets as you would any other gold alloy. I do not
    believe there could possibly be any hazard to using it or even melting it.
    However, there is no harm in wearing the proper type of respirator, rated
    for such use. And if you are concerned about toxicity, set up a fan behind
    you, blowing gently toward an open window in front of you, before heating.

I welcome comments on this explanation from anyone who can add anything.
Alan Revere


#2

I agree with Alan, treat them as normal. I have been a jeweler for 23
yrs. Over the years I periodically run across a ring that has been
exposed to mercury. Usually a nurse that broke a thermometer or a dental
assistant that was careless. The mercury adheres to the gold giving it a
white color almost like rhodium plating a yellow gold ring. The method I
was taught to remove it was to take my torch and gently brush the flame
across the ring. The mercury will disappear. I recommend you wear the
appropriate respirator if you try this technique or do in a ventilated
area. My best guess if the gold had a greenish cast was that was a
certain level of silver in it. Robert Benham @Robert_Benham


#3
  1. Not all good is retrieved with mercury. As a matter of fact, I think
    mercury “leaching” is illegal and rarely done anymore. It is an
    interesting process, though, whereby gold is recovered by pouring
    mercury over it, often in river beds. The gold “melts” into the mercury
    which then carries it further downhill. Then the gold-bearing mix is
    heated to evaporate the mercury, leaving the gold behind.

G’day; here’s another penn’orth:- In some of the creeks of New Zealand,
and in some ancient sand dunes on the West Coast of the South Island the
gold is so fine that it is hard to see. (there’s a very old ballad
called, “There’s Gold, Bright Fine Gold In The Mataura”)The miners crushed
the consolidated sandy rock and washed it down a wooden slope with bits of
wood nailed across it, (called a riffle box) which caught the larger bits.
Next came a piece of sheepskin fleece (Jason’s Golden Fleece?) which
caught the finer stuff, though in the later years carpet seemed to work
better . Finally came copper sheets, coated with plenty of mercury, and
this caught the very finest gold, amalgamating with it. The amalgam was
scraped off as a thick yellowish paste and placed in a retort made of iron
pipe, and the main vessel was heated in a fire (usually the camp fire).
The mercury was thus recovered, and the spongy gold was melted and poured
into a bucket of water, then they waited for the itinerant gold buyer to
come around to the goldfield.

The very early prospectors, with the very finest gold in their pan used to
amalgamate it with mercury. Then they’d get the biggest potato they could
find, hollow it out and leave a sort of gallery. They would then put the
putty-like gold amalgam on their shovel, put the spud over it and heat it
on the fire. The mercury distilled off, collecting in the gallery, from
whence it could be poured out to be reused, and the gold sponge would
remain on the shovel. An early example of Kiwi ingenuity, and I’ve
actually seen it done.
I hope not too many ate the well cooked spud afterwards.

I really can’t imagine the prospectors - who were all extremely poor -
wasting expensive mercury by pouring it in the creek in the hope they’d
get it back further down.

These days they treat the crushings with dilute sodium cyanide solution
and bubble air through the liquid, which dissolves the gold then plate out
the gold electrically, which leaves a far more pure gold than the mercury
method.

A lot cheaper too.
Cheers,

       / \
     /  /
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 /  /__| \      @John_Burgess2
(______ )       

At sunny Nelson NZ (in winter)