Colloidal Transport And Flocculation Are The Causes Of The Hyperenrichment Of Gold In Nature

[afreakofnature]

The Mystery Formation of Extremely Rich Gold Veins Might Finally Be Solved

MICHELLE STARR

24 MAY 2021

Gold, for all its wonderful uses, isn't hugely abundant in Earth's upper layers. For each ton of crust material, there's an estimated just 0.004 grams of the precious metal.

Yet somehow, there are regions that contain "bonanza" abundances - hyper-enrichment, in the scientific parlance. How these gold veins form in time spans as short as days from hydrothermal systems that only contain trace amounts of the metal has been a geological mystery.

It's one that now has an answer, from the most unlikely of clues: the separation and clumping of fat particles in soured milk.

"Scientists have long known that gold deposits form when hot water flows through rocks, dissolving minute amounts of gold and concentrating it in cracks in the Earth's crust at levels invisible to the naked eye," geoscientists Anthony Williams-Jones and Duncan McLeish of McGill University in Canada stated in a Q&A.

"In rare cases, the cracks are transformed into veins of solid gold centimetres thick. But how do fluids with such low concentrations of gold produce rare ultrahigh-grade gold deposits? Our findings solve the paradox of 'ultrahigh-grade' or 'bonanza' gold formation, which has frustrated scientists for over a century."

Milk is an aqueous solution made up of several components, one of which is microscopic globules of fat. At the pH level of fresh milk - very close to neutral - these fat particles have a negative charge, which causes them to repel each other.

The souring process involves bacteria in the milk converting lactose to lactic acid, lowering the pH level accordingly. This causes the surface charge on the fat particles to break down, and the fat particles separate from the milk serum and clump together with each other via coagulation, forming a sort-of gross decomposing milk fat jelly.

Williams-Jones, McLeish and their colleagues found a similar process when using transmission electron microscopy to study gold deposits from the Brucejack Mine in British Columbia. This is one of the spots around the world where bonanza-grade mineralization can be found, up to 41,582 grams per ton.

It's long been accepted that gold is transported by way of fluid through Earth's crust. However, in order to reach the abundances found in hyper-enrichment zones, previous studies suggested that the gold may have been dissolved in high concentrations in fluids containing chlorides or bisulfides, and transported and deposited that way.

The other possibility is a colloidal solution, with solid nanoparticles of gold dispersed throughout hydrothermal and geothermal fluids. Since the gold nanoparticles hold a charge (like milk fat), they repel each other. When the charge breaks down, the gold particles clump together in a process similar to coagulation, known as flocculation.

This has been indirectly demonstrated in the past; now, McLeish and colleagues have observed how it actually happens.

"We produced the first evidence for gold colloid formation and flocculation in nature and the first images of small veins of gold colloid particles and their flocculated aggregates at the nano-scale," Williams-Jones and McLeish said.

"These images document the process by which the cracks are filled with gold and, scaled up through the integration of millions of these small veins, reveal how bonanza veins are formed."

For this process, the concentration of gold in the geothermal fluids only has to be a few parts per billion. It flocculates to form a jelly-like substance, which gets trapped in cracks in Earth's crust to form rich gold veins.

This finding suggests that rich gold deposits may be more common than we thought, and may have occurred in several other contexts than previous estimates had allowed for. If other studies and further examination can back it up, the research could give us a new toolkit for understanding and locating gold deposits around the world.

"We suspect that the colloidal processes that operated at Brucejack and other bonanza gold systems may also have operated to form more typical gold deposits. The challenge will be to find suitable material to test this hypothesis," Williams-Jones and McLeish said.

"The next step will be to better understand the reasons why colloid formation and flocculation occurred on the scale observed and reconstruct the geological environment of these processes."

The research has been published in PNAS.

[Cascade Steven]

Thanks for sharing this article.   In my own research on gold deposit formation and gold nugget formation I have found a variety of hypothesis for gold deposition starting with the work of Lindgren in 1901.  These hypothesis can be organized into groups of hypothesis by deposit model depending upon whether one is considering vein deposits, disseminated deposits, replacement deposits, skarn deposits, greenstone gold deposits or other models.  And there seems to be some overlap between hypothesis within given groups and between groups. As implied in the article, there may more than one process involved and gold vein formation may differ from some aspects of gold nugget formation.   However, it is interesting to consider that there may be an overlap in the two processes (vein formation and nugget formation).  And as mentioned (or implied) in the article, this new insight and understanding may present new opportunities for exploration and nugget patch location.  The original academic paper contains some interesting images and accompanying descriptions.  This research poses an interesting question:  is this process an over-arching or umbrella type of process that is active in the formation of many of the various types of deposits (i.e. deposit models)?  Only further research will provide the answer.  However, the more we understand about the geology of gold formation and deposition the greater the probability of success, and this research has certainly added to both our understanding and our arsenal of exploration tools.

[GotAU?]

I like the part that says that deposition of bonanza type deposits may be more common than thought.

[Sheppo]

1 hour ago, GotAU? said:

I like the part that says that deposition of bonanza type deposits may be more common than thought.

Yep, try finding it with your metal detector or shovel and pans though. Much of it will be extremely deep in the ground, or in countries we can’t access.

[afreakofnature]

3 hours ago, Cascade Steven said:

Thanks for sharing this article.   In my own research on gold deposit formation and gold nugget formation I have found a variety of hypothesis for gold deposition starting with the work of Lindgren in 1901.  These hypothesis can be organized into groups of hypothesis by deposit model depending upon whether one is considering vein deposits, disseminated deposits, replacement deposits, skarn deposits, greenstone gold deposits or other models.  And there seems to be some overlap between hypothesis within given groups and between groups. As implied in the article, there may more than one process involved and gold vein formation may differ from some aspects of gold nugget formation.   However, it is interesting to consider that there may be an overlap in the two processes (vein formation and nugget formation).  And as mentioned (or implied) in the article, this new insight and understanding may present new opportunities for exploration and nugget patch location.  The original academic paper contains some interesting images and accompanying descriptions.  This research poses an interesting question:  is this process an over-arching or umbrella type of process that is active in the formation of many of the various types of deposits (i.e. deposit models)?  Only further research will provide the answer.  However, the more we understand about the geology of gold formation and deposition the greater the probability of success, and this research has certainly added to both our understanding and our arsenal of exploration tools.

No worries, I am always on the lookout for how nuggets form which could lead to new areas to detect.  Not sure if you have this article but this one is interesting as well from 2007.

2007 - Gold Nuggets Supergene or Hypogene - Hough et al.pdf

[Cascade Steven]

af:  thanks for the link.

[Valens Legacy]

Thanks again for sharing this information, I as a newbie can use all the help I can get to use.

Good luck on your next outing and let us know if you find that great big 100kg nugget!

[Gold Hound]

Very interesting, thank you for the info.

I have my own theory that gold and other elements are formed by transmutation by way of a combination of heat, pressure, catalist minerals and sound frequency.

They have demonstrated transmutation in nuclear reactors and post nuclear explosion.

But I belive that this can occur in with way less of an energy relese and at lower temp with the aid of naturally occuring feromagnetic catalist fluxes and sound freequency.

[GotAU?]

2 hours ago, Gold Hound said:

Very interesting, thank you for the info.

I have my own theory that gold and other elements are formed by transmutation by way of a combination of heat, pressure, catalist minerals and sound frequency.

They have demonstrated transmutation in nuclear reactors and post nuclear explosion.

But I belive that this can occur in with way less of an energy relese and at lower temp with the aid of naturally occuring feromagnetic catalist fluxes and sound freequency.

Is that about nuclear fusion where two or more lighter atomic nuclei are combined to for a new heavier element? That does occur in stars forming the lighter elements, but there's only one [natural] way to make gold and the heavier elements from other lighter elements, and it isn't in Earth or from our Sun (luckily!). The latest and most accepted theory with direct evidence is from colliding neutron stars, the ones that death spin into each other.

Radioactive decay in the Earth formed Argon, lead and other elements from heavier ones, but it always forms lighter, more stable nuclei as an end product.