Earthquakes Cause Quartz to Form Large Gold Nuggets by Creating Electric Charges
TL;DR
Scientists have discovered how earthquakes help turn quartz into large gold nuggets. Gold is naturally found in quartz veins, but the mystery of how it accumulates into large nuggets has puzzled researchers for years. Using simulations, they found that seismic activity generates electric charges in quartz, which cause gold to solidify from hydrothermal fluids. This process, repeated over many earthquakes, creates massive gold nuggets found in quartz veins. The study provides new insights into how valuable gold deposits form during earthquakes.
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Scientists have finally uncovered how earthquakes help turn quartz into large gold nuggets, solving a mystery that has baffled researchers for years.
Gold is naturally found in quartz, which is the second-most common mineral in Earth’s crust after feldspar. However, unlike most gold deposits, those found in quartz tend to gather into large nuggets. These nuggets are found in what geologists call quartz veins—cracks in quartz-rich rocks that are periodically filled with hydrothermal fluids from deep within the Earth.
“Gold forms in quartz all the time,” explained Chris Voisey, a geologist at Monash University in Australia and lead author of a new study published in Nature Geoscience. “What’s unusual is the formation of really large gold nuggets. We didn’t understand how that process worked—how a large amount of gold could mineralize in one small spot,” Voisey told Live Science.
Hydrothermal fluids transport gold atoms from deep within the Earth and flush them through quartz veins, meaning gold should theoretically be evenly distributed within the cracks rather than forming nuggets, according to Voisey. These nuggets are exceptionally valuable and account for up to 75% of all gold ever mined, according to the study.
Two critical clues helped Voisey and his colleagues solve this mystery. The first was that the largest gold nuggets are found in orogenic gold deposits, which form during earthquakes. The second clue was that quartz is piezoelectric, meaning it generates its own electric charge when subjected to geologic stress, such as the stress caused by an earthquake.
“When you put these facts together, it all fits together almost too perfectly,” Voisey said. The researchers discovered that earthquakes cause rocks to fracture, forcing hydrothermal fluids into quartz veins, where they deposit dissolved gold. At the same time, the stress from the earthquake causes the quartz veins to create an electric charge that interacts with the gold, leading it to solidify.
Gold clusters in specific areas because “gold dissolved in solution will preferentially deposit onto existing gold grains,” Voisey explained. “In essence, gold acts as an electrode for further reactions by taking on the voltage generated by nearby quartz crystals.”
This process means that in quartz veins, gold gradually solidifies into larger clusters with each earthquake. The biggest orogenic gold nuggets found so far weigh around 130 pounds (60 kilograms), according to Voisey.
To test this theory, the researchers simulated the effects of an earthquake on quartz crystals in the lab. They submerged the crystals in a liquid containing gold and mimicked seismic waves to create a piezoelectric charge. The experiment confirmed that quartz under geologic stress could generate enough voltage to precipitate gold out of the solution.
The simulation also verified that gold tends to solidify on existing gold deposits within quartz veins, which helps explain the formation of large gold nuggets.
“Seeing pre-existing gold act as the catalyst or ‘lightning rod’ that other gold attaches to was incredibly exciting,” Voisey said.
One implication of the study is that scientists can now produce large gold nuggets in the lab, but Voisey emphasized, “It’s not alchemy. You need gold in a solution, and then you’re simply transferring it from liquid form to attaching to something else.”
However, the findings don’t provide new information for geologists and mining companies about where to find gold nuggets. The best current technology offers is a device that detects piezoelectric signals from quartz at depth, Voisey noted. “This can tell you where quartz veins are—but not whether those veins contain gold.”
