The Guardian reported on September 3 that large gold deposits often form deep underground, along cracks that run through quartz, but the cause is unclear. Now, scientists have come up with an explanation for this phenomenon.
Geologist Chris Voisey said hydrothermal fluids carry gold atoms from deep below and push them through quartz veins. In theory, the gold is dispersed throughout the cracks, rather than concentrated in clumps.
The researchers found that the earthquake fractured the rock and pushed hydrothermal fluids into quartz veins, filling them with dissolved gold. In response to the earthquake’s pressure, the quartz veins also created an electrical charge that reacted with the gold, causing it to precipitate and solidify.
“The gold concentrates at specific points because the dissolved gold in the solution preferentially condenses on pre-existing gold particles,” explains Chris Voisey. “The gold acts as an electrode for further reactions by absorbing the voltage generated by nearby quartz crystals.”
This means that the gold solidifies in the quartz veins in larger clumps after each earthquake. Geologist Chris Voisey said that so far, the heaviest gold found is about 60kg.
Researchers simulated the effects of earthquakes on quartz crystals in the lab. They immersed the crystals in a liquid containing gold and recreated seismic waves to create piezoelectricity.
Experiments confirmed that quartz can generate enough piezoelectricity under geological pressure for gold to condense. Simulations also confirmed that gold often solidifies on top of existing gold ore in quartz veins. This helps explain the formation of large gold masses.
