Gold, with all its wonderful uses, is not in abundance in the upper layers of the earth. For every ton of material that flakes, there are an estimated 0.004 grams of the precious mineral.
However, somehow there are areas that contain an abundance of “richness” – over-enrichment, in scientific language. How gold veins form in such a short time as days from hydrothermal systems that contain only trace amounts of the mineral has been a geological mystery.
This is the answer that now has one of the most probable indicators – the separation and clumping of fat particles in the curd.
Scientists have long known that gold deposits form when hot water flows through the rocks, causing minute amounts of gold to dissolve and concentrate in cracks in the earth’s crust at levels invisible to the naked eye. Geologist Anthony Williams-Jones on Duncan McLeish From McGill University in Canada mentioned in Q&A.
In rare cases, the cracks turn into veins a centimeter thick of pure gold. But how do liquids with low concentrations of gold produce extremely rare deposits of gold? Gold formation, which has frustrated scientists for more than a century.
Milk is an aqueous solution consisting of several components, including microscopic fat globules. At the pH value of fresh milk – nearly neutral – these fat molecules have a negative charge, which causes them to repel each other.
The acidification process involves bacteria in the milk that convert lactose into lactic acid, which reduces the pH value accordingly. This breaks down the surface charge on the lipid particles, and the fat particles separate from the whey and agglomerate with each other by coagulation, creating a kind of coarse milk gel dissolved with water.
Williams-Jones, McLeish and colleagues discovered a similar process using transmission electron microscopy to study gold deposits from the Brucejack Mine in British Columbia. This is one of the locations around the world where richness class minerals can be found, up to 41,582 grams per ton.
It has long been accepted that gold is transported by liquids across the Earth’s crust. However, to achieve the abundance found in overly fertilized areas, Previous studies It has been suggested that gold may have been dissolved in high concentrations in liquids containing chlorides or disulfides, transported and deposited in this way.
Another possibility is A. Colloidal solutionWith solid gold nanoparticles dispersed by hydrothermal and geothermal fluids. Because gold nanoparticles carry a charge (like milk fat), they repel each other. When the charge decomposes, the gold particles group together in a process similar to coagulation, also known as coagulation surgeon.
This has been proven indirectly in the past. Now MacLeish and his colleagues note how this actually happens.
“We produced the first evidence of colloid formation and flocculation in nature and the first images of small veins from colloidal gold particles and their flux nanocomposites. Williams Jones and MacLeish said.
“These photos document the process of filling the cracks with gold, which was amplified by the inclusion of millions of these tiny veins, and illustrate how bonanza veins are formed.
For this process, the gold concentration in soil fluids should be only a few parts per billion. It cools to form a gel, which gets confined in the cracks in the earth’s crust to form rich golden veins.
This result indicates that rich gold deposits may be more common than we thought, and may have occurred in several contexts different from what previous estimates permitted. If other studies and additional research can support this, the research could provide us with a new toolkit for understanding and locating gold deposits around the world.
“We suspect that colloidal processes performed at Brucejack and other Bonanza gold systems may have also served to form the typical gold deposits. The challenge will be to find a suitable material to test this hypothesis,” Williams Jones and MacLeish said.
“The next step will be to understand the causes of colloid formation and flocculation at the observed scale and to better reconstruct the geological environment for these processes.”
The research has been published in PNAS.