Will Mercury dissolve gold? This age-old debate constantly surfaces within the circles of prospectors.

In the 1940 book titled Fire Assaying by O.C. Shepard (Associate Professor of Mining and Metallurgy) & W. F. Dietrich (Teacher of Mining and metallurgy) on page 35 it reads: “Liquid mercury dissolves about 1 mg of gold per gram of mercury,…” Thus, according to these authors there is no question, but I’ve read in newer chemistry books that mercury does not dissolve gold.

Several years ago I accidently discovered tiny anomalous spheres of gold. Upon careful study I eventually determined that these gold balls originated from a rusty gold pan. Evidently, mercury was at some time in the distant past used to collect fine, possibly flour gold during the concentration process of panning.

Apparently, over time the desert sun caused the mercury to vaporize leaving tiny spheres of gold in the shallow microscopic pits of the rusty gold pan. The point is, I know of no naturally occurring gold spheres, therefore, can it be safely assumed that mercury dissolved specks of gold, which assumed the shape as mercury metal?

Because of this gold ball discovery and prior mercury microchems I decided it is appropriate to further test and see with my eyes if Hg does dissolve Au.

Assuming that Hg does actually dissolve Au the looming question becomes—how would gold be recovered if it is molecularly intimate with/in mercury?

History indicates that retorting mercury collects gold as an amalgam. And, if a mercury and gold amalgam is heated to the melting point of gold then all the mercury should distill away from the gold, but does it? Furthermore, who has conducted a specific gravity test on ultra pure mercury, verses mercury that was amalgamated with gold and retorted or distilled 3 times? What if gold and mercury are so intimate that the micron/submicron or nano-gold particles distill with the mercury?

I have purchased so-called triple distilled Hg only to find when dissolved in HNO3 that microscopic gold crystals are present. Therefore, if the gold is actually dissolved by mercury, then how much gold was lost by the old-timers? Better yet, where is that lost gold?

If the majority of gold mined is invisible to the eye, then I begin to suspect that huge amounts of gold may have been inadvertently lost by those who became experts at retorting. But, far more likely – tremendous amounts of gold must have been lost when the chamois was used to wring-out mercury. Thus, if this hypothesis has any semblance of validity then it would seem prudent to seek out the old prospectors sites where mercury was used and if possible retrieve this mercury or pan the dirt for the gold.

This test began at 2PM – 2-19-08.and concluded at 2:30PM – 2-26-08.

10x – A fragment of gold taken from a large piece of 99.9+ pure gold bullion.
Size of Au fragment is approximately 0.095” x 0.045”

40x – A magnified view of the preceding image.

10x – The previous fragment of gold was heated with hand-held propane torch on plaster tablet gold till it melted and formed this gold prill.
Prill size = 0.025”

40x – It is apparent that some contamination in this 99.9+ fine gold is present as the thin reddish flacks seen on the surface of this prill.
Based upon prior examinations and microchems of so-called pure gold bullion I have seen this before and it appears to be Rhodium.

10x – Showing the relative size of these two spheroids that will be merged.
It took some coaxing to get these two metals to unit, but when the event happened it was instantaneous.
Hg size is approximately 0.10+”
The white and brownish specs are debris under the glass slide on the microscope stage.

The following images are the end result of the amalgamation of this mercury sphere and gold prill.

40x – Concentrated Nitric acid digested all the mercury resulting in this crystalline gold prill.
The microscope lenses are very dirty from acid splattering which has caused the blackish specks in field of view.

40x – The same gold prill as imaged previously, but with black microscope stage and different area of focus.

50x – A magnified view of the previous image better illustrating the gold prill surface.

50x – Same as previous image, but a different area of focus.

70x – A magnified view of the previous image to better illustrate some of the gold crystals.

70x – Gold crystals, originating from the gold prill, which are laying on the glass slide next to the gold prill.
These crystals cannot be seen by the unaided eye.

70x – 4 sided pyramidal gold Crystals that has dropped off the gold prill as the HNO3 acid attacked the mercury.

When dissolving mercury there is what I call a somewhat antiseptic odor, however, this time and with a little heat there was an odd, indescribable non-offensive odor.

No further study was conducted on this gold prill that had been amalgamated with mercury.

It is extremely interesting that this resultant crystalline gold prill had increased in size from 0.025” to 0.035”. This suggests that mercury has infiltrated deep within the gold. Or, perhaps has actually molecularly merged with the gold and the nitric acid cannot attack what mercury may be residing with or within the gold.

For those who have eyes and can appreciate virgin ground, but, without going into details, this little test ought to inspire an inquisitive prospector, because it appears that mercury becomes extremely intimate with gold and may well be a clue that can lead to significant discovery.

The amalgamation of Gold and Mercury

40x – A fragment of 99.9% bullion gold that was submerged in concentrated HNO3 to clean away any extraneous microscopic debris.
Size of Au fragment = 0.04” x 0.04” at maximum length and width,

40x – The gold fragment and a 0.05”sphere of Mercury in 1 drop of distilled H2O on a glass slide.
The Hg was pre-cleaned in 1 drop of HNO3 and 1 drop of H2O to eliminate microscopic particles that notoriously cling to mercury.

40x – The Mercury is attached to the gold and is slowly beginning to encapsulate the gold fragment.

Strangely, when I tried to unit these 2 metals the gold fragment seemed to be replled from the mercury. But, soon the mercury seemed to be attracted to the gold fragment.

The greenish-gray color on the gold is due to the shadow from the mercury.

40x – The mercury is slowly engulfing the gold.

40x – The Hg continues to encapsulate the gold.

The microscope lens is being reflected on the mercury surface.

40x – After 40 minutes the mercury has completely encapsulated the gold fragment.
There are 3 gold points protruding from the mercury, which corresponds well with the shape of the gold fragment.

40x – after 1 hr there are only 2 gold pointed tips protruding from the mercury surface, which has a fractured appearance.

40x –  The gold-mercury amalgam is subjected to 1 drop HNO3 in a fresh drop of H2O, because after an hour the original 1 drop of water had almost dried.

40x – Because the single drop of HNO3 did not want to dissolved the amalgam after a few minutes another 2 drops HNO3 + 1 drop H2O was added, causing this vigerous reaction.

40x – After several minutes the gold-mercury amalgam has shrunk in over-all size and is exhibiting a shape that apparently contours the shape of the gold fragment.

40x – The Hg finished dissolving in nitric acid and left this pitted appearing gold fragment.

50x – A magnified view of the preceding image.

70x –A magnified view of the preceding image.
The ccd microscope camera is not capable of 3D images, so only a portion of the non-flat surface is in focus.
What appears to be pits is actually raised cubic and rectangular shapes, leaving deep spaces between each gold crystal.

When examining this fundamental question of Hg dissolving Au another question comes to mind—is the Mercury and nitric acid creating some kind of dissolving action on the gold that HNO3 cannot do? Or, did the Mercury actually penetrate into the surface of the gold and when the nitric acid dissolved the Mercury this anomalous gold surface remained?

Flattened a piece of 999 gold
Cleaned with concentrated HNO3 to eliminate any iron that may have inadvertently adhered to the gold as it was being hammered flat

Overall size of this piece of gold:
Length = 0.15”  max
Width = 0.095” max
Thickness (min) =  0.0013”

20x -- hemostat clamp made the grooves (ridges & valleys).

40x – A magnified view of the preceding image.

20x – The thin piece of flattened gold being held in the jaws of a hemostat  so I can make a measurement of the thickness of the gold.

40x – A magnified view of the preceding image.

10x – A view of the flattened gold and mercury on glass slide in a drop of water.
Size of the Hg sphere = aproximately1/8th inch

10x – The Hg sucked-up the Au quickly and I only was able to capture this image barely before the mercury engulfed all the gold.

Placed the Hg + Au in plastic vial with a little water at 5PM, 3-4-08 at a room temperature of 70 degrees F till 11AM 4-5-08.

The following images show the results of what happened to the gold when the mercury was dissolved away from the gold.

32x – The Hg is almost completely dissolved and in a porcelain evaporating dish that was used to dissolve the mercury.

40x – A magnified view of the preceding image and still in the porcelain dish.
Note the gold crystal formations residing on-top of this flat gold surface.

50x – A magnified view of the same gold, but focused upon one group of gold crystals, which I cannot determine if this is a growth or deposition.

70x – A magnified view of the preceding image and attempting to focus on the mass of gold crystals.

50x – The gold has been transferred to a glass slide, which now shows the crimp of the hemostat.

70x – A magnified view of the preceding image. I cannot get better resolution of the irregular surface to clarify the tiny crystals of gold.
When I view deep into the cracks my eye can see that the same crystalline appearance appears suggesting that the Hg had permeated deep inside the gold.

50x – Another view of the gold attempting to illustrate the crimp and larger Au crystals.

40x – Another view of the overall flattened gold fragment.

10x – Notice that there are now only 2 crimp marks (valleys & ridges), whereas originally there were three.

Max length = 0.12”
Max width = 0.93”
Max thickness =  0.001”

There remains no doubt in my mind that mercury can dissolve gold.
I can only begin to wonder what the effects of mercury and gold would be in a desert climate at 100+ degrees, or if I had used more mercury.