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Science

How Do Gold Nuggets Form? Earthquakes May Be the Key (nationalgeographic.com) 44

Posted by msmash from the unraveling-mysteries dept.
Scientists have finally solved a long-standing mystery about the geologic process behind these large pieces of gold found in quartz rock. From a report: Gold has always been a hot commodity. But these days, finding a nugget isn't too tricky: Much of the world's gold is mined from natural veins of quartz, a glassy mineral that streaks through large chunks of Earth's squashed-up crust. But the geologic process that put gold nuggets there in the first place was a mystery. Now, a new study published today in Nature Geoscience has come up with a convincing, and surprising, answer: electricity, and earthquakes -- lots of them.

Those nuggets owe their existence to the strange electrical properties of common quartz. When squished or jiggled, the mineral generates electricity. That drags gold particles out of fluid in Earth's crust. The particles crystallize out as grains of gold -- and, over time, with enough electrical stimulation, those grains bloom into nuggets. "If you shake quartz, it makes electricity. If you make electricity, gold comes out," says Christopher Voisey, a geologist at Monash University in Australia and the lead author of the new paper. Earthquakes are the most likely natural source of that shaking, and the team's lab experiments show that earthquakes can make gold nuggets.

The idea that gold nuggets appear because of electricity instead of a more conventional geologic process is, at first, a peculiar thought. But "it makes complete sense," says Thomas Gernon, a geoscientist at the University of Southampton in England and who was not involved with the new work. Quartz veins host a disproportionate number of gold nuggets and their environments experience plenty of earthquakes.
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How Do Gold Nuggets Form? Earthquakes May Be the Key More

How Do Gold Nuggets Form? Earthquakes May Be the Key

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  • Cool. So with this discovery we now can engineer and manufacture gold just like we've done with the diamond industry while displacing all those old school economics of actually mining the shit out of the planet? This development is probably a good thing for us all over the long term, including the environment.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      >So with this discovery we now can engineer and manufacture gold just like we've done with the diamond industry while displacing all those old school economics of actually mining the shit out of the planet?
      No, elemental gold is still extremely rare, unlike carbon.

      • No, elemental gold is still extremely rare, unlike carbon.

        Thank you for taking the time and effort to explain this to me.

      • Nah. Take some cheap element, like lead, and add some protons to it. Easy gold. Tune in next week when we show how a car can run a thousand miles on a tank of ordinary tap water.

        • Re: (Score:2)

          by habig ( 12787 )

          Nah. Take some cheap element, like lead, and add some protons to it. Easy gold.

          Apparently Lawrence had to explain to the White House why doing this with his cyclotrons wouldn't destabilize the gold standard, and then how much it would actually cost to turn a useful amount of lead into gold. I don't know if that's a real story or a fairy tale us physicists like to tell each other about past giants.

    • "So with this discovery we now can engineer and manufacture gold just like we've done with the diamond industry"

      Er, no. The deal with gold is not that it comes in nuggets, but that it is gold, as opposed to diamonds, which are just fancy carbon, carbon being common as dirt. You're not going to "manufacture" gold unless you accomplish the transmutation of elements, which is extremely difficult and this doesn't help with at all.

    • Yes, I've harnessed exploding stars in my basement.

    • It's not getting shaken hard enough to fuse elements.

      • I don't have access to the full article but depending on where these aqueous gold sources are maybe this knowledge could be used to harvest from there, but whether that's easier or less damaging than mining isn't clear to me.

        • The amount of gold in seawater is tiny, so you're talking about a massive undertaking for far less reward than simply locating and digging up existing gold deposits.

          Seawater has lots of useful stuff in it, but not in useful densities.

          • I assume the quartz gold electroplating reaction is more "subterranean aquifer" type source than "open ocean" but I'm no geologist.

            • For an industrial process, the ocean has what you need and is easier to reach.

              • How much casual violence are you doing to ocean inhabitants?

              • Sea water is easy to reach but a fellow Baron_Yam said it wasn't suitable for gold extraction.

                • You seem to have missed the part about anything other than simply digging up existing deposits is economically infeasible.

                  But if you're insisting on an artificial process, it's still easier to process seawater than to replicate the conditions that generate natural concentrated gold deposits

    • Re: (Score:2)

      by pjt33 ( 739471 )

      Yes, instead of mining gold companies will now try to aggregate the tiny quantities of it in seawater by electrifying the oceans. A definite win for the environment.

      • When the topic of gold in seawater comes up, people often don't realize the impact that *orders of magnitude* have regarding the expense of extraction. There are lots of videos, charts, lessons, etc. explaining it but I like to point to the salt flats. The first step in getting the gold out might be removing the water, right? That's expensive; but there are plenty of primordial seas that dried up and left salt flats. That work is done. These places are mined in fact--for salt. Nobody even considers ge

        • "If those nuggets formed in quartz veins because of the continuous percolation of gold-bearing water at similar concentrations, the input of time and/or energy is beyond any reasonable human scale."

          What if some energy pulse from a star exploding caused currents to flow through the earth in quartz like wires? What if the earth, or parts thereof, became like a battery?

          Why do mining companies call manganese nodules a "battery in a rock"? If all the chemicals needed to make a battery are in the rock already, an

        • This. There is gold in lots of places where it isnâ(TM)t worth the cost to extract it. Live in the Pacific Northwest? You can find gold in the sand sold at most hardware stores. Just not enough to pay for the sand much less the effort and equipment it would take you to extract it.

    • Maybe you could do something with sea water and use the wave energy to squeeze the quartz.

      It would probably take too long to be profitable for humans, though.

    • This doesn't create gold from nothing. It causes the gold already present in the hot molten soup of the earth in the cracks between quartz crystals. Without that hot molten gold-infused soup, this process is useless to us for obtaining gold.

  • Duh (Score:1, Offtopic)

    by BigEddieD ( 9191421 )
    Everyone knows nuggets come from electricity. Like when you grow weed, you need electricity, to power the lights, which grows dank nuggets. This is first grade shit guys, come on!

  • An exceptionally well-written abstract (Score:5, Informative)

    by davide marney ( 231845 ) on Tuesday September 03, 2024 @11:16AM (#64759026) Journal

    From the study [nature.com]:

    Gold nuggets occur predominantly in quartz veins, and the current paradigm posits that gold precipitates from dilute, hot, water±carbon dioxide-rich fluids owing to changes in temperature, pressure and/or fluid chemistry. However, the widespread occurrence of large gold nuggets is at odds with the dilute nature of these fluids and the chemical inertness of quartz. Quartz is the only abundant piezoelectric mineral on Earth, and the cyclical nature of earthquake activity that drives orogenic gold deposit formation means that quartz crystals in veins will experience thousands of episodes of deviatoric stress. Here we use quartz deformation experiments and piezoelectric modelling to investigate whether piezoelectric discharge from quartz can explain the ubiquitous gold–quartz association and the formation of gold nuggets. We find that stress on quartz crystals can generate enough voltage to electrochemically deposit aqueous gold from solution as well as accumulate gold nanoparticles. Nucleation of gold via piezo-driven reactions is rate-limiting because quartz is an insulator; however, since gold is a conductor, our results show that existing gold grains are the focus of ongoing growth. We suggest this mechanism can help explain the creation of large nuggets and the commonly observed highly interconnected gold networks within quartz vein fractures.

    There are a couple of somewhat unusual terms: "orogenic formation" meaning "mountain-forming", e.g., earthquakes, and "deviatoric stress" meaning "shape changing".

    Note that the gold is in solution in the surrounding rock. It's not that the piezo-driven reactions "create" gold, rather they just precipitate it from solution to the quartz surface, where it can crystallize. There is a huge amount of gold out there, it's just so very hard to get at it.

    • I'm sure that won't stop talking heads selling "in-situ, dispersed gold" in cubic yards of the rockies on their radio shows as if they were the investment of the century.
  • Comment removed based on user account deletion

    • Wrong.

      https://www.usgs.gov/faqs/how-... [usgs.gov].

      About 244,000 metric tons of gold has been discovered to date (187,000 metric tons historically produced plus current underground reserves of 57,000 metric tons). Most of that gold has come from just three countries: China, Australia, and South Africa. The United States ranked fourth in gold production in 2016.
      All of the gold discovered thus far would fit in a cube that is 23 meters wide on every side.

    • Re: (Score:2)

      by tragedy ( 27079 )

      Eighteen cubic yards of gold is about 262 tons of it. That's not even close to all the gold on Earth. Russia alone, for example, has 1000 tons of gold reserves in a vault at a central bank in Moscow and another 500 tons at a second vault in St. Petersburg. So that's not just gold on Earth, but gold that's been mined, refined and purchased by a central bank.

  • LOL, so nature creates its Bitcoin through the same process :)))

  • Remember the other recent discovery that manganese nodules are producing enough electricity to electrolyze seawater?

  • Whereas gold-nuggets=IT.

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