Gold has long been valued both for its rarity and aesthetic appeal, serving not only as a medium of exchange or a piece of jewellery but also as a catalyst in chemical reactions and an electrical conductor in modern technology. It is usually found as gold nuggets in quartz veins, crystallised silicon dioxide, and its formation process has been debated by scientists for many years.
However, the recent research entitled "Gold nugget formation from earthquake-induced piezoelectricity in quartz," which was published in Nature Geoscience, suggests that earthquakes may play a significant role in creating these valuable nuggets.
"The standard explanation is that gold precipitates from hot, water-rich fluids as they flow through cracks in the Earth's crust," said Dr Chris Voisey, the lead author of the study.
"As these fluids cool or undergo chemical changes, gold separates out and becomes trapped in quartz veins," he said.
Despite its widespread acceptance, this theory falls short in explaining the formation of large gold nuggets, particularly given the extremely low concentration of gold in these fluids.
"The stressed quartz not only electrochemically deposited gold onto its surface, but it also formed and accumulated gold nanoparticles," said study co-author Professor Andy Tomkins, from the Monash University School of Earth, Atmosphere and Environment.
"Remarkably, the gold had a tendency to deposit on existing gold grains rather than forming new ones."
This is because, while quartz is an electrical insulator, gold is a conductor.
Once some gold is deposited, it becomes a focal point for further growth, effectively "plating" the gold grains with more gold.
"Our discovery provides a plausible explanation for the formation of large gold nuggets in quartz veins," said Dr Voisey.
These findings open up new avenues of possibility in understanding the formation of gold nuggets, showing probable linkage between seismic activities and generation of these precious metals within quartz veins. This might cast a new light on the geological processes that generate one of the world's most treasured materials.
