Gold nuggets are not just beautiful pieces of jewelry or symbols of wealth; they may also owe their existence to the immense pressure and stress of earthquakes. A recent study suggests that earthquakes could trigger a chemical reaction that causes tiny particles of gold to come together and form larger nuggets.
According to Chris Voisey, a geologist at Monash University in Australia and co-author of the study, this discovery sheds light on a new process of gold formation, particularly explaining how large gold nuggets might be created. Traditionally, experts believed that dissolved gold in fluids could seep into cracks in quartz, a common mineral in the Earth’s crust, to form smaller gold deposits. However, the mechanism behind the formation of larger nuggets remained a mystery.
The study, published in Nature Geoscience, proposes that the geological stress generated by earthquakes activates a unique property of quartz known as “piezoelectricity.” This property allows quartz to generate an electric charge when subjected to mechanical stress, facilitating the formation of larger gold nuggets.
Quartz’s piezoelectric effect stems from its atomic structure, which consists of positively charged silicon and negatively charged oxygen atoms. When the material is compressed or stretched, the arrangement of these atoms changes, leading to the generation of an electric field. This change in electric state enables gold nanoparticles in the fluid to interact with the quartz surface, initiating a chemical reaction that results in the accumulation of gold particles.
To test their hypothesis, the researchers simulated the electric field produced by quartz under earthquake-like forces and observed the accumulation of gold nanoparticles when subjected to seismic-wave-like pressures. The findings suggest that episodic earthquakes play a crucial role in the formation of large gold nuggets, particularly in orogenic deposits formed at the collision zones of tectonic plates.
James Saunders, a consulting geologist not involved in the study, acknowledges the significance of the research and calls for further investigation into the specifics of this process. He highlights the need to understand the duration and intensity of earthquake forces required to form gold deposits and the variability in nugget formation within quartz cracks.
While studying piezoelectricity on a large scale poses challenges, geologists remain optimistic about the potential of this research. Aubreya Adams, a geologist at Colgate University, emphasizes the importance of quantifying stress variations in the Earth’s crust to validate the study’s findings.
Voisey and his team plan to expand their experiments by exploring different pressures and temperatures to validate their theory further. This study marks a promising start in understanding the role of earthquakes in the formation of large gold nuggets and opens up new avenues for future research in the field of geology.
