Crack open a piece of white quartz from a gold mine, and you might just spot shiny metal streaks inside. For over a century, geologists believed that intense, hot fluids dissolved gold and left it behind as conditions shifted. But here’s the catch: these fluids usually carry only tiny bits of gold. So, how do we end up with large nuggets inside quartz, which doesn’t mix easily with much? This question still puzzles scientists.
Recently, geologist Christopher Voisey from Monash University, along with a team at CSIRO and the Australian Centre for Neutron Scattering, explored a new idea. They proposed that electricity generated during earthquakes might help create gold deposits in quartz. This notion ties back to a property of quartz called piezoelectricity. Essentially, when quartz is stressed—like during an earthquake—it develops electrical charges.
In earthquake zones, rocks grind against each other, causing stress in the quartz. As this happens, the team wanted to find out if those electrical charges could actually move electrons, pulling gold out of solution and bonding it to quartz surfaces.
To test this, they conducted laboratory experiments. They placed quartz in solutions with dissolved gold, simulating natural conditions underground. When they stressed the quartz, tiny gold specks and clusters appeared on its surface. This suggests a process called electrochemical deposition, where dissolved gold ions gain electrons and turn into solid gold on quartz.
Interestingly, when they started with quartz that already had some gold, the results were even more striking. The existing gold grains acted like tiny magnets for new gold, causing clusters to form around them. This process highlighted an important pattern: once a small gold particle forms, it attracts more gold during each stress event, meaning larger nuggets accumulate over time.
Research indicates that earthquakes turn quartz into a sort of natural battery. Each seismic event charges the quartz, enabling the deposition of gold onto existing grains. Most of the earth’s large gold nuggets come from quartz veins, particularly in orogenic gold systems. These areas are believed to supply around 75% of the gold mined throughout history.
The new findings add layers to our understanding of gold formation. Traditional views still hold—hot fluids have to move through rock fractures, and the changes in chemistry are vital. However, this research emphasizes how earthquakes might promote significant gold growth in quartz, making the relationship between gold and quartz even clearer.
Remarkably, Dr. Voisey stated, “In essence, the quartz acts like a natural battery, with gold as the electrode, slowly accumulating more gold with each seismic event.” This study sheds light on how seismic activity plays a crucial role in building those impressive gold nuggets.
For more information, you can read the full study published in the journal Nature Geoscience here.
