This was the most interesting news I saw today. Earthquakes cause gold to form in quartz? It sounds like impossible magic at first, but once you put the bits together, it makes great sense!
As a kid, I remember finding gold in veins of quartz crystals and being fascinated by the idea of precious metals hidden within common rocks. Scientists have recently solved the mystery of how large nuggets of gold get trapped in quartz veins, and the answer lies in the power of earthquakes.
Researchers have discovered exactly how earthquakes trigger quartz into forming large gold nuggets — finally solving a puzzle that has puzzled geologists for decades. Gold naturally forms in quartz, the second-most abundant mineral in Earth’s crust after feldspar. But unlike other types of gold deposits, those found in quartz often cluster into giant nuggets floating in the middle of what geologists call quartz veins[1][2].
These veins are cracks in quartz-rich rocks that periodically get pumped full of hydrothermal fluids from deep within the crust. “Gold forms in quartz all the time,” said Chris Voisey, a geologist at Monash University in Australia and the lead author of a new study published in the journal Nature Geoscience. “The thing that’s weird is really, really large gold nugget formation. We didn’t know how that worked — how you get a large volume of gold to mineralize in one discreet little place.”[4]
Hydrothermal fluids carry gold atoms up from the deep and flush them through quartz veins, meaning gold should theoretically become evenly spread in the cracks rather than concentrated into nuggets. However, the largest nuggets occur in orogenic gold deposits, which are deposits that form during earthquakes[1][2][4].
The key lies in the unique properties of quartz. It is the only abundant piezoelectric mineral on Earth, meaning it creates its own electric charge in response to geologic stress, such as the stress generated by earthquakes[1][2][3]. “When you actually put it together, it almost works out a bit too neat,” Voisey said.
The researchers found that earthquakes fracture rocks and force hydrothermal fluids up into the quartz veins, filling them with dissolved gold. In response to the stress, quartz veins simultaneously generate an electric charge that reacts with the gold, causing it to precipitate and solidify[1][2][4].
Gold concentrates in specific spots because “gold dissolved in solution will preferentially deposit onto pre-existing gold,” Voisey explained. “Gold is essentially acting as an electrode for further reactions by adopting the voltage generated by the nearby quartz.”[4]
This means that in quartz veins, gold solidifies into clusters that grow bigger with each earthquake. The largest orogenic gold nuggets found to date weigh around 130 pounds (60 kilograms)[4].
To test this idea, the researchers simulated the effect of an earthquake on quartz crystals in the laboratory. They submerged the crystals in a liquid containing gold and replicated seismic waves to generate a piezoelectric charge. The experiment confirmed that under geologic stress, quartz can produce a large enough voltage to precipitate gold out of solution and preferentially solidify it on top of existing gold deposits[4].
One of the implications of the study is that scientists can now make large gold nuggets in the lab, but Voisey cautions, “It’s not alchemy. You’d have to have gold in a solution and then you just move it from basically being in a liquid to sticking to something.”[4]
The results don’t give geologists and exploration companies new clues as to where to mine for gold nuggets, but they do provide a fascinating insight into the interplay between Earth’s physical and chemical processes. As Voisey puts it, “This new understanding of gold nugget formation not only sheds light on a longstanding geological mystery but also highlights the interrelationship between Earth’s physical and chemical processes.”[2]
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[1] https://www.nature.com/articles/s41561-024-01514-1
[2] https://www.sci.news/geology/gold-nugget-formation-13225.html
[3] https://www.newscientist.com/article/2445930-earthquakes-may-explain-how-huge-gold-nuggets-form-in-quartz-rock/
[4] https://www.livescience.com/planet-earth/geology/earthquakes-can-trigger-quartz-into-forming-giant-gold-nuggets-study-finds
[5] https://www.theguardian.com/science/article/2024/sep/02/scientists-find-seismic-role-in-formation-of-large-gold-nuggets
[6] https://futurism.com/the-byte/gold-nuggets-formed-electricity
[7] https://www.abc.net.au/news/science/2024-09-03/piezoelectricity-could-be-behind-gold-nugget-formation/104287142
[8] https://theconversation.com/how-do-you-make-a-giant-gold-nugget-take-a-vein-of-quartz-add-a-few-thousand-earthquakes-236694