Scientists catch Earth's core leaking gold toward the surface
“When the first results came in, we realized that we had literally struck gold!"
The world’s largest stash of gold isn't at Fort Knox: It's locked away in Earth’s core.
Now, new research from Göttingen University in Germany suggests that some gold might be leaking from the core into the mantle and the crust, bringing it another step closer in the long, and slow, upward journey to the surface.
The findings, published this month in the journal Nature, trace the precious metal Ruthenium (Ru) in volcanic rocks from Hawaii back to the core-mantle boundary, which lies more than 3,000 kilometres underground.
Giant underground reservoir
Most of Earth's gold and other precious metals like platinum and palladium are believed to have sunk into the metallic core during the planet’s early, molten days.
We can access gold from Earth's crust, but what lies there represents only 1 per cent of the total quantity of gold on the planet.
More than 99 per cent of it is thought to be in the core.
If that 99 per cent were placed on the surface, there would be enough to blanket all the land on Earth in a half-metre layer of gold.
Tiny clues in lava
The authors of the new study say tiny differences in isotopes hold clues about when deep-earth elements appear closer to the surface. One isotope, 100Ru, is found in higher concentrations in the core than in the mantle. Using refined techniques, researchers detected high levels of 100Ru in Hawaiian lava samples.
“When the first results came in, we realized that we had literally struck gold!" says Dr. Nils Messling from the university’s Department of Geochemistry, in a statement.
"Our data confirmed that material from the core, including gold and other precious metals, is leaking into the Earth’s mantle above.”
The core is leaking!
The discovery challenges the assumption the planet’s core is geochemically sealed off from the surrounding mantle and suggests some of the core’s metal-rich contents leak upwards.
But don't expect a gold rush anytime soon. Digging 2,900 km down to access the minerals isn't realistic, but the paper does offer new insight into what goes on deep underground.
The findings suggest all siderophile elements, i.e., those that prefer to bond with iron and were drawn into the core early in Earth’s formation, may be gradually leaking out. That includes ruthenium, gold, platinum, rhodium, and palladium.
“Our findings not only show that the Earth’s core is not as isolated as previously assumed,” says Professor Matthias Willbold, also of the Department of Geochemistry, in the same statement.
“We can now also prove that huge volumes of super-heated mantle material – several hundreds of quadrillion metric tonnes of rock – originate at the core-mantle boundary and rise to the Earth’s surface to form ocean islands like Hawaii.”
This research not only adds to our understanding of Earth’s interior but could also reshape what we know about the evolution of other rocky planets across the solar system.
Header image: Graphic representation of Earth’s shell structure showing the super-heated metallic inner core in the centre, followed by the solid outer core, the rocky mantle and the thin crust towards the surface. New research from the University of Göttingen demonstrates that some precious metal-rich material from the core is leaking into the Earth’s mantle above. University of Göttingen/ (OpenAI)