Crack open a chunk of white quartz from a gold mine and you might see bright metal streaks inside. For more than a century, geologists looked at scenes like that and said, “Gold got here in hot water.”

They meant that super‑hot fluids moved through cracks in the rock, carried dissolved gold, and then left that gold behind when conditions changed.

That idea explains a lot, but it raises a tough question: those fluids usually carry only tiny amounts of gold compared with the volume of water, so how can that kind of solution leave behind large nuggets inside quartz, a mineral that hardly reacts with anything?

That puzzle still bothers geologists.

Electric quartz and gold growth

Geologist Christopher Voisey at Monash University, together with colleagues at CSIRO and the Australian Centre for Neutron Scattering (ANSTO), tested a different twist on the story: electricity generated during earthquakes can help build gold inside quartz veins.

They focused on a property of quartz called piezoelectricity. When a quartz crystal is squeezed, bent, or twisted, its atomic structure shifts enough to separate positive and negative charges.

One side of the crystal becomes relatively positive, the other relatively negative, so a voltage appears across it. The same effect drives quartz watches, but there it is carefully controlled by tiny electrical circuits.

Fault zones that host gold deposits contain many quartz veins. In those zones, rocks break, slip, and grind past each other as tectonic plates move. During a quake, stress builds up in the quartz and is released, so piezoelectric charges appear and fade.

The team asked a simple, testable question: are those voltages strong enough to move electrons, pull gold out of solution, and attach gold directly to quartz surfaces?

Earthquakes, quartz and gold in the lab

To probe that idea, the scientists ran a series of controlled lab experiments. They placed pieces of quartz into solutions containing dissolved gold, similar to hydrothermal fluids deep underground.

Then they mechanically stressed the quartz to imitate the sudden push and pull of an earthquake and examined the crystal surfaces with high‑resolution microscopes.

Metallic gold appeared: bright specks, clusters of nanoparticles, and small pseudo‑hexagonal crystals perched on the quartz grains.

These shapes match what researchers expect from electrochemical deposition, where dissolved gold ions gain electrons and turn into solid metal on a surface.

Instead of always using quartz with no metal, they also started with quartz that already contained a little gold, much closer to a natural vein. In that setup, the small gold grains acted as conductors within the system.

When stress created an electric field in the quartz, those metal grains concentrated the field around themselves, so new gold nanoparticles tended to grow on and around the older ones, forming halos and tight clusters.

Under these conditions, the electric charges could “plate” gold out of solution, so fresh metal coated the quartz surface and thickened the deposits.

From seed to nugget

Once there is even a tiny “seed” of gold, that grain becomes the preferred place for more gold to plate out during each stress event.

Quartz acts as an electrical insulator and does not let electrons move easily through its interior, which makes it hard to start nugget growth from nothing.

Gold, on the other hand, conducts electricity well. As soon as a small conductive grain forms, it concentrates the electric field at its surface and lets electrons move efficiently right where they are needed.

As the reactions continue, the system develops a “rich get richer” pattern: fewer, larger gold pieces rather than many tiny ones.

In another set of experiments, the team immersed quartz in a liquid filled with gold nanoparticles.

When they stressed the quartz, those particles no longer stayed spread out evenly in the fluid. They drifted, gathered, and clumped into larger clusters directly on the quartz surface.

“The results were stunning,” said study co-author Professor Andy Tomkins, from the Monash University School of Earth, Atmosphere and Environment.

“The stressed quartz not only electrochemically deposited gold onto its surface, but it also formed and accumulated gold nanoparticles,” Tomkins explained. “Remarkably, the gold had a tendency to deposit on existing gold grains rather than forming new ones.”

This behavior shows that electric fields around stressed quartz can gather and concentrate mobile gold particles even before they fuse into a continuous grain.

Voltages in real quartz veins

In a fault zone filled with such veins and bathed in gold‑bearing fluids, each earthquake briefly turns the system into an electrochemical cell.

On some quartz surfaces, electrons accumulate, and dissolved gold species pick up those electrons and become metallic gold.

On other surfaces, complementary reactions occur, and charged ions in the fluid move to balance out the charges.

Each “squeeze” – each earthquake – charges the quartz a little and drives a small amount of gold plating onto existing grains or onto fresh nucleation sites.

Results from the uncoated quartz gold nanoparticle (AuNP) experiment. (A) BSE image of AuNPs on the quartz surface exhibiting localized clustering. (B) BSE image of the area outlined in a. (C) SE image of the square area outlined in a. (D) EDS image of the square area in a highlighting the chemistry of sample area. BSE, backscattered electron; SE, secondary electron; EDS, energy-dispersive spectroscopy. Credit: Nature Geoscience. Click image to enlarge.

Gold from quartz and earthquakes

The electrical mechanism does not replace classic models of gold formation. Hot, gold‑bearing fluids still have to move through fractures at suitable temperatures and pressures, and changes in fluid chemistry still help metal separate from solution.

The new work adds an extra step: piezoelectric voltages during earthquakes focus gold growth onto particular spots in quartz, especially where some metal already exists.

Most of the world’s large gold nuggets come from quartz veins in orogenic gold systems, which supply roughly three‑quarters of the gold mined in human history.

In many of these deposits, miners encounter large lumps of metal in thick veins instead of a thin dusting of gold spread everywhere.

“In essence, the quartz acts like a natural battery, with gold as the electrode, slowly accumulating more gold with each seismic event,” Dr. Voisey concluded.

This study suggests that seismic activity, by charging and discharging quartz over geologic time, helps explain the tight partnership between gold and quartz and the rare cases where nature builds especially hefty nuggets.

The full study was published in the journal Nature Geoscience.

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