Deep beneath the Earth’s crust, a geological mystery has puzzled scientists for decades: how do large, pure gold nuggets form within veins of quartz? A new study led by geologists from Monash University proposes an electrifying answer — literally. Their research suggests that electricity generated during earthquakes could be the missing key to understanding this process.
Gold, Quartz, and Earthquakes: A Surprising Trio
Most of the world’s gold is hidden in underground veins of quartz, a mineral formation that geologists have long studied but still do not completely understand. These veins can be found deep within the Earth’s crust. Here, superheated, gold-laden fluids from the planet’s core rise and cool. As they flow through cracks and fissures in the rock, these fluids can leave behind precious deposits.
Traditional theories suggested that gold precipitates from these hot fluids as they cool or undergo chemical changes, becoming trapped in quartz. However, this explanation does not fully account for the formation of large gold nuggets, which can appear suspended in quartz without clear evidence of chemical reactions.
Dr. Chris Voisey and his team at Monash University decided to investigate an alternative explanation involving a unique property of quartz known as piezoelectricity. This phenomenon occurs when a material generates an electric charge in response to mechanical stress.
When you compress these materials, they undergo a slight deformation. This then causes a shift in their internal electrical balance, producing a voltage. This effect is so precise and reliable that it’s used in many technologies, from the tiny sensors in our phones that detect touch to the ignition systems in gas stoves that create a spark.
“It seemed almost too convenient,” Voisey noted during an interview with ABC News. Quartz is not only the most abundant piezoelectric mineral on Earth, but it’s also where we find these large gold nuggets.
A New Gold Formation Mechanism
To test their hypothesis, the researchers set up an experiment to mimic the conditions in the crust during an earthquake. They suspended quartz crystals in a solution rich in gold, then applied mechanical stress to replicate seismic waves.
The results were striking. Under these conditions, the stressed quartz crystals not only deposited gold onto their surfaces but also seemed to attract additional gold particles, forming larger accumulations.
“The gold had a tendency to deposit on existing grains rather than forming new ones,” explained Professor Andy Tomkins from the Monash University School of Earth, Atmosphere and Environment, a co-author of the study.
This finding suggests that once a small amount of gold adheres to the quartz, it acts like a lightning rod, drawing in more gold during subsequent seismic events. This process could explain how large nuggets of pure gold form over time. The quartz would repeatedly generate piezoelectric voltages that cause gold to deposit from surrounding fluids.
Implications for Mining and Beyond
The study, published in Nature Geoscience, has sparked interest not only among geologists but also within the mining industry. Understanding this new mechanism of gold formation could lead to more efficient exploration techniques. “Knowing that there is an electric component involved could change how we search for these deposits,” said Rob Hough, a mineral resources director at CSIRO who was not involved in the study.
While the experiments by Voisey and his team primarily produced small gold particles, they believe this piezoelectric mechanism could, under the right conditions, lead to the formation of much larger nuggets. The study also opens new avenues for applying piezoelectricity in mineral processing, potentially reducing the cost and environmental impact of gold extraction.
As Voisey reflects, “Understanding these processes doesn’t just satisfy our scientific curiosity—it could help us harness natural forces in ways we haven’t even imagined yet.”
