How Earthquakes Help Form Gold Nuggets

Large gold nuggets like this may owe their formation to earthquakes

Post Author - Ellis Nolan

Here’s some science Yosemite Sam might like to hear: According to a recent study, earthquakes may have a role in the development of large gold nuggets. Eureka!

Most gold comes from deposits inside swaths of quartz, the second most common mineral in Earth’s crust. Usually when a deposit forms, it comes from gold dissolved in fluid in the lower levels of the Earth’s crust. This fluid seeps into cracks in quartz deposits, forming a nugget. However, only a certain amount of fluid can pass through these cracks in the quartz, thus limiting the size of the gold deposit. Scientists hypothesized that gold nanoparticles in the fluid could aggregate and cause larger nuggets within the quartz, however, the nanoparticles seemed to lack the chemical energy to do so.

According to the researchers, what might allow larger deposits to form has to do with a property of quartz called “piezoelectricity.” Put simply, piezoelectricity is the tendency to create an electric charge after mechanical stress is applied. Because of quartz’s chemical structure, stretching or squashing of the substance leads to an asymmetrical distribution of electric charge, which creates an electric charge.

Gold accumulation in the quartz piezocatalysis model

Scientists believe this extra charge could be what allows gold particles to “stick” to quartz deposits and create larger nuggets. To test this hypothesis, they placed quartz samples into a fluid with gold nanoparticles (a sort of seismic cereal: part of a balanced breakfast!). Then, an electric field was created to simulate an earthquake stretching the quartz. The results seem to show that the researchers were on the right path. That being said, they stress that the study was a “pilot” and that more research on the method must be done. Perhaps even more explanations for large nuggets will pan out in the future!

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