Expensive Shake

A groundbreaking study proposes that the secret to the formation of large gold nuggets lies in the earth-shaking power of earthquakes.

Researchers from Monash University in Melbourne, Australia, discovered that seismic activity could induce a phenomenon known as the piezoelectric effect in quartz, a common mineral in the Earth’s crust, leading to the accumulation of gold particles into sizeable nuggets.

Published in Nature Geoscience, the study addresses a long-standing geological mystery about how can large gold nuggets form despite the low concentrations of gold typically found in natural fluids.

For example, the formation of a 22-pound gold nugget would generally require an enormous volume of water with dissolved gold – about the equivalent of five Olympic swimming pools.

“This was always a bit of a conundrum, especially when there isn’t field evidence supporting the alternative gold-forming processes,” Christopher Voisey, a geologist at Monash University and co-author of the study, told Scientific American.

Voisey and his team conducted experiments that simulated the conditions of an earthquake. They placed quartz crystals in a fluid containing dissolved gold and subjected them to quake-like forces. The stress on the quartz generated an electric charge – known as the piezoelectric effect – that facilitated the accumulation of gold nanoparticles on the mineral’s surface.

“This mechanism can help explain the creation of large nuggets and the commonly observed highly interconnected gold networks within quartz vein fractures,” the researchers wrote.

The study provides a plausible explanation for the formation of orogenic gold deposits, which are commonly found in regions where tectonic plates have collided.

These deposits account for about 75 percent of the world’s mined gold, which typically comes from cracks in quartz veins. The findings could also have practical applications in gold prospecting, potentially guiding prospectors to rich gold deposits, other researchers told the Guardian.

While the hypothesis is promising, further research is needed to fully understand the process.

Voisey added that he and his colleagues plan to explore different pressures and temperatures to refine their understanding of how piezoelectricity can contribute to the formation of gold.