Earth might be harboring a quadrillion tons of diamonds

Researchers believe that there are more than a quadrillion tons of diamonds more than 100 miles underneath the surface of the Earth's interior.

Tyler MacDonald | Jul 16, 2018

A new study from MIT researchers in collaboration with other universities suggests that there could be over a quadrillion tons of diamonds underneath the Earth's interior. However, the minerals are buried over 100 miles underneath the surface, which is deeper than any drilling missions have ever reached.

Researchers estimate that the cratonic rootsthe oldest, most immovable portions of rock located beneath the center of most continental tectonic platescould contain 1 to 2 percent diamond.

"This shows that diamond is not perhaps this exotic mineral, but on the [geological] scale of things, it's relatively common," said Ulrich Faul, a research scientist from MIT's Department of Earth, Atmospheric, and Planetary Sciences. "We can't get at them, but still, there is much more diamond there than we have ever thought before."

"Diamond in many ways is special," he continued. "One of its special properties is, the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine."

The data revealed that a rock with a composition of just 1 to 2 percent diamond would be sufficient to create the higher sound velocities measured by scientists. In addition, this minuscule fraction would not alter the overall density of a craton, which is typically less dense than surrounding mantle rock.

"They are like pieces of wood, floating on water," Faul said. "Cratons are a tiny bit less dense than their surroundings, so they don't get subducted back into the Earth but stay floating on the surface. This is how they preserve the oldest rocks. So we found that you just need 1 to 2 percent diamond for cratons to be stable and not sink."

The findings were published inGeochemistry, Geophysics, Geosystems.

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