Earthquakes may be the cause behind the formation of gold nuggets, according to a new study appearing in the journal Nature Geosciences.
Scientists have long thought gold comes from hot fluids flowing through cracks in the Earth's crust, with quartz veins acting as a primary host, but the low concentration of gold in these fluids makes it hard to explain the existence of large gold nuggets.
The research team, led by geologist Dr. Chris Voisey, tested a theory involving piezoelectricity, also known as the ability of quartz to generate an electric charge when subjected to stress, such as during an earthquake.
The team simulated earthquake conditions in a lab and, under a microscope, they found that stressed quartz could electrochemically deposit gold onto its surface.
"The results were stunning," study co-author Professor Andy Tomkins, from the Monash University School of Earth, Atmosphere and Environment said in a statement.
"The stressed quartz not only electrochemically deposited gold onto its surface, but it also formed and accumulated gold nanoparticles. Remarkably, the gold had a tendency to deposit on existing gold grains rather than forming new ones."
Dr. Voisey likened quartz to a natural battery, with gold as the electrode, gradually accumulating more gold with each earthquake.