Is Earth’s core leaking gold and other precious metals to the surface?

Scientists have found robust suggesting that Earth’s inner core, long considered completely sealed off, is slowly releasing gold and other precious metals into the layers above.

This revelation comes from a detailed isotope study of volcanic rocks, specifically basalt samples from Hawaii, which shows that some of the world’s most valuable elements may have originated not just from meteorites or the planet’s mantle, but from the very centre of Earth itself.

Geochemists from the University of Göttingen in Germany, including Nils Messling and Matthias Willbold, have published their findings in the scientific journal Nature, revealing how specific isotopes act as tracers for material that originated in Earth’s metallic core.

How Earth’s core is seen as a hidden reservoir

For decades, scientists have known that the overwhelming majority of Earth’s gold — along with elements like platinum, palladium, rhodium and ruthenium — is not found in the crust or even the upper mantle, but locked away in the core, buried beneath nearly 3,000 kilometres of dense rock.

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This concentration of heavy elements occurred during Earth’s early years, over 4.5 billion years ago, when the planet’s internal structure began to differentiate.

Heavier elements sank toward the centre during a process known as the iron catastrophe, leaving the outer layers comparatively depleted.

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According to estimates, the quantity of gold sequestered in the core is so vast that, if extracted and spread evenly over the land surface, it could cover every continent with a 50-centimetre-thick layer of gold.

Yet, until recently, this immense subterranean reserve was believed to be geologically unreachable and completely cut off from the crust.

That assumption has now been upended.

How scientists tracked core-derived isotopes in volcanic rock

The Göttingen researchers focused on analysing isotopic compositions in rocks formed from deep-Earth magmatic activity.

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They targeted ruthenium, a rare and heavy element that exhibits subtle isotopic differences depending on its source. These differences had previously been too minute to distinguish.

But by refining their laboratory techniques, the team was able to detect and compare ruthenium isotopes with unprecedented precision.

Using samples from basaltic lava flows in the Hawaiian islands — an area known for volcanic activity stemming from deep mantle plumes — the researchers discovered an elevated concentration of the isotope ruthenium-100.

This variant is consistent with material originating from Earth’s core, as opposed to the surface or upper mantle.

“Our data confirmed that material from the core, including gold and other precious metals, is leaking into the Earth’s mantle above,” said Nils Messling, one of the lead authors of the study. “When the first results came in, we realised that we had literally struck gold!”

The core-derived signature in the volcanic rock was not limited to ruthenium. It suggests that other siderophile elements — those with an affinity for iron and which bonded with it in the early, molten Earth — may also be part of the upward movement from core to mantle, and eventually, to the crust.

How core material reaches the surface

The study provides compelling evidence that deep mantle upwellings — also called mantle plumes — transport material from near the core-mantle boundary to the surface.

These massive columns of superheated rock rise through the mantle and erupt through oceanic crust to form volcanic islands such as those in Hawaii.

“We can now also prove that huge volumes of superheated mantle material—several hundred quadrillion metric tons of rock—originate at the core-mantle boundary and rise to the Earth’s surface to form ocean islands like Hawaii,” said study co-author Matthias Willbold.

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The volume and force of this process are immense, although it happens over geological timescales spanning millions of years.

The volcanic rocks that emerge during these eruptions carry chemical and isotopic clues from the depths, making them natural record-keepers of Earth’s internal dynamics.

What this means for future research

The discovery opens new avenues for understanding how Earth’s internal systems have evolved over billions of years.

Prior to this discovery, the prevailing understanding among Earth scientists was that the planet’s core, encased beneath the solid silicate mantle and crust, was an isolated and chemically inert reservoir.

The new research not only confirms that elements like ruthenium and possibly gold are slowly migrating upward, but it also introduces the use of isotopic “tracers” to monitor and quantify this migration in future studies.

Ruthenium, in particular, may serve as a powerful tool for understanding the interactions between Earth’s layers.

“Precious metals such as ruthenium are highly concentrated in the metallic core but extremely depleted in the silicate mantle,” the researchers wrote in their study.

While many of Earth’s surface metals were believed to have arrived via meteorite bombardment during the early years of the solar system, this study shows that at least some of those metals may have originated from within the planet itself.

“Our findings open up an entirely new perspective on the evolution of the inner dynamics of our home planet,” the researchers concluded.

While practical access to these deeply buried resources remains impossible with current technology, the scientific insight gained from these findings may influence everything from geochemistry to planetary science.

This revelation also has implications beyond Earth. If core leakage of precious metals is possible here, similar processes may occur on other rocky planets.

Though no gold rush will result from this research, its value lies in the new understanding it offers about Earth’s inner mechanics.

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With input from agencies