A replica of the Welcome Stranger, a gold nugget weighing almost 100 kilograms found in Australia in 1869
Ian Dagnall/Alamy
Earthquakes have long been associated with the formation of gold nuggets within quartz, a common mineral known for its inert properties. The discovery of enormous gold nuggets weighing nearly 100 kilograms has puzzled scientists for years, as the process of their formation remained a mystery.
Researchers, led by Chris Voisey from Monash University in Melbourne, have shed light on this phenomenon. They found that when quartz is subjected to pressure, it generates an electric field that attracts gold dissolved in water, offering a possible explanation for the formation of large gold nuggets.
The unique structure of quartz plays a crucial role in this process. Unlike other minerals, quartz crystals lack a center of symmetry, making them susceptible to changes in their electromagnetic configuration when exposed to seismic activity. This phenomenon, known as piezoelectricity, results in the production of electricity within the quartz crystals.
During earthquakes, gold-bearing hydrothermal fluids from deep within Earth’s crust are pushed up through fractures in the rock. While the gold in these fluids is extremely dilute, the electric field generated by the piezoelectric quartz concentrates the gold into nuggets within veins.
To test their hypothesis, the research team conducted experiments using quartz crystals immersed in a solution containing gold and subjected to pressure. The results showed that pressured quartz crystals attracted and concentrated gold, with the presence of iridium enhancing this effect by mimicking increased seismic activity.
According to Voisey, once gold starts depositing on the quartz, it acts as a conductor, attracting more gold and leading to the rapid growth of larger gold nuggets. This process creates a feedback loop where the presence of gold on the quartz surface attracts additional gold, similar to a lightning rod.
Topics:
