When Earth first took shape more than 4.5 billion years ago, it set aside its most valuable riches for its heart. As the planet melted and separated into layers, dense metals like gold, platinum, and ruthenium sank through the viscous primordial rock, pooling in the nascent core. By most estimates, more than 99.999 percent of Earth’s gold disappeared into this buried reservoir — out of reach, sealed beneath 3,000 kilometers of solid and molten mantle.
But a new study published in Nature offers a startling suggestion: some of that gold may be leaking back out.
Researchers from the University of Göttingen have detected traces of ruthenium in Hawaiian lava that bear a distinctive isotopic signature — one that matches the chemical fingerprint of material that should only exist in Earth’s core.
“When the first results came in, we realized that we had literally struck gold,” said Nils Messling, a geochemist at Göttingen and the lead author of the study. “Our data confirmed that material from the core, including gold and other precious metals, is leaking into Earth’s mantle above.”
The finding adds weight to a long-simmering hypothesis in geochemistry: that Earth’s core is not entirely cut off from the rest of the planet. Instead, it may be exchanging material with the mantle above. The idea has implications for how scientists understand the deep Earth, and perhaps for how gold and other rare elements ended up in the crust we mine today.
The Vault Below
To understand how gold ended up in the core in the first place, you have to rewind the planet. In its infancy, Earth was molten and chaotic. Heavy elements like gold and ruthenium sank toward the center, pulled by gravity into a forming metallic core. The rocky outer layers were left nearly stripped of these prized metals.
Later, a cascade of space debris — meteoritic shrapnel from the Solar System’s leftovers — delivered a small replenishment to the crust and mantle. These meteorites carried a slightly different isotopic flavor of ruthenium. And it’s this that scientists can now use to trace where elements came from.
This is the clue Messling’s team seized upon. Ruthenium exists in multiple isotopes. One of them, 100Ru, is slightly more abundant in core materials than in the mantle. The difference is subtle, but with new purification techniques and painstaking mass spectrometry, the researchers detected a consistent elevation of 100Ru in Hawaiian lavas.
That shouldn’t happen — unless something from the core is mixing into the molten rock rising from deep within Earth.
“Basalts from Hawaii have higher 100Ru than the ambient mantle,” the researchers wrote. Combined with anomalous tungsten isotope values — another potential marker of core–mantle exchange — this “is diagnostic of a core contribution to their mantle sources.”
The rocks in question emerged from mantle plumes — columns of hot, buoyant rock rising from the deep interior. The Hawaiian plume, which gave rise to the island chain over tens of millions of years, may originate at the boundary between the mantle and the core.
That boundary, once thought impermeable, may not be so secure after all.
Gold’s Backdoor Escape Route
Volcanoes like those in Hawaii erupt lava that originates from melting deep within the mantle. That lava carries with it chemical signatures from the mantle’s source — and occasionally, as it turns out, whispers from even deeper.
“The Earth’s core is not as isolated as previously assumed,” said Matthias Willbold, a co-author of the study. “We can now also prove that huge volumes of super-heated mantle material — several hundreds of quadrillion metric tons of rock — originate at the core–mantle boundary and rise to Earth’s surface to form ocean islands like Hawaii.”
But how does core material make the leap?
The researchers propose two scenarios. One involves the direct mixing of core metal into the base of the mantle. In this model, the ruthenium and tungsten anomalies would be due to just 0.25 percent of the plume’s source material deriving from the core. But this approach creates a problem. It should also cause noticeable increases in other metals, which are not seen in the rocks.
So, they explored a second model, one that’s more subtle.
As Earth’s core slowly cools over geological time, it may crystallize thin layers of metal oxides. These would be enriched in certain elements like tungsten and ruthenium, but depleted in others. These oxides could form a distinct chemical layer atop the core, and some of that material could mix into the rising mantle plume.
This model also explains why highly siderophile (a term that means “iron-loving”) elements like gold and platinum — though theoretically present — are not found in high concentrations in the volcanic rocks. Their levels may simply be too low to detect. Or they may have been partitioned into inaccessible phases during melting.
Still, the presence of even a trace of ruthenium from the core hints at a larger truth: Earth’s deepest interior may be slowly, almost imperceptibly, feeding material back toward the surface.
How Much Gold Are We Talking About?
What’s rising isn’t pure gold or raw core metal. It’s a geochemical admixture — mantle rock that’s been laced with a whisper of core-derived ruthenium and tungsten. But that’s enough to reveal that some of Earth’s most coveted metals might not be as out of reach as we assumed.
Let’s be clear: This isn’t going to be a get-rich-quick scheme. No one is drilling into the Hawaiian volcanoes to mine their molten gold. The amounts making it to the surface are minuscule.
Still, the implications are huge.
Gold is one of many “highly siderophile elements”. In planetary bodies, these elements eagerly bond with iron and tend to vanish into metal-rich cores. The fact that even a trace amount is reappearing in volcanic rocks suggests that deep Earth is more chemically connected than it looks.
If even a sliver of the core’s precious metal cache is creeping back upward, it challenges a long-standing idea that Earth’s internal layers are chemically sealed off from one another.
“We’re talking about a continuous, ongoing process of exchange,” said Messling. “It’s like the Earth is very slowly regifting its buried treasure.”
By pairing isotope data with meteorite comparisons and modeling Earth’s accretion history, the study makes the strongest case yet that the planet’s core—its most secretive, inaccessible domain—is not hermetically sealed. It leaks.
Not fast. Not much. But enough.
“Whether these processes that we observe today have also been operating in the past remains to be proven,” Messling said. “Our findings open up an entirely new perspective on the evolution of the inner dynamics of our home planet.”
And maybe, just maybe, they help answer an age-old question: Where did Earth’s gold really come from?
It didn’t just fall from space. Some of it, it seems, is clawing its way up from the deep.
