Envato Elements
The core at the center of the Earth
Isotopic anomalies detected in elements such as tungsten and ruthenium suggest that there was a mixing between core and mantle material, which indicates that gold and other metals may be gushing to the surface.
A vast gold discovery in central China is reigniting one of geology’s biggest debates: where do Earth’s precious metals really come from?
At the end of 2024, Chinese authorities announced that more than a thousand tons of gold may be under the already explored Wangu gold field, in Hunan province, potentially being the largest deposit of precious metals ever identified, valued at around .
Despite its cultural and economic importance, gold is not a truly rare metal, but rather difficult to access.
According to Matthias Willbold, from the University of Göttingen, around 99.9% of Earth’s precious metals are trapped deep within the planet’s core. When Earth formed 4.54 billion years ago from debris orbiting the young Sun, it was initially molten. Heavy elements, such as iron, sank, dragging with them so-called “siderophile” elements — that is, elements that bind to iron — including gold, platinum and tungsten.
For decades, scientists believed that these metals remained sealed in the core, almost 3000 kilometers below the surface. But growing evidence suggests the story may be more complex.
According to , an ancient explanation argues that the precious metals found in the Earth’s mantle and crust were later brought by meteorites during a period known as the Late Great Bombardment, about 3.9 billion years ago. Asteroid impacts will have enriched the mantle again with gold and other heavy elements after the nucleus has already formed, preventing them from sinking further.
However, a competing theory proposes that the Earth’s core may be “leaking” minimum quantities of material upwards. The clues come from subtle isotopic anomalies in elements like tungsten and ruthenium, found in volcanic rocks linked to deep mantle plumes, like those beneath Hawaii and Iceland. Some researchers argue that these anomalies indicate residual mixing between core and mantle material over billions of years.
Not all scientists are convinced, with some theorizing that two meteorite impactsby itself, could explain the isotopic signatures. If core leakage were widespread, similar evidence should emerge in other siderophile elements, which, to date, has largely not happened.
Adding another layer to the puzzle is helium. High ratios of primordial helium-3 detected in deep volcanic plumes suggest material from Earth’s earliest history is still reaching the surface. Whether this gas originates in the mantle or even deeper in the core remains unknown.
Although any escape involves only tiny amounts, the implications are profound. Long-term exchange between the core and mantle can shape Earth’s magnetic field, volcanic activity and geological life as a whole.
Comparisons with Mars and Venus highlight the importance of this. Mars cooled rapidly and lost its magnetic shieldwhile Venus has no tectonic plates to regulate internal heat. Earth appears to occupy a delicate middle ground, with its layers still interacting.
Whether gold deposits like Wangu originated from ancient asteroid impacts or a slowly “breathing” core, scientists say the answer will reshape our understanding not only of Earth’s past, but also of what makes planets like ours capable of supporting life.
