Under our feet, there is a huge treasure: more than a million billion tons of diamond are below the surface of the Earth, according to researchers at the Massachusetts Institute of Technology (MIT). But do not expect a diamond rush: the massive treasure trove is 145 to 240 kilometers below the surface of the planet, well beyond the distances reached by drilling today.
“We can not reach them but there are a lot more diamonds than we thought,” said Ulrich Faul, a researcher at the Department of Planetary, Atmospheric and Earth Sciences at MIT. “It shows that diamond may not be this exotic mineral. At the scale of things, it is relatively common,” he added.
Using seismology to analyze how sound waves pass through the Earth, researchers have detected this treasure in rocks called cratons, which extend across the earth’s crust and sink into the mantle. The project began when scientists were surprised by observations that sound waves were significantly accelerating through the roots of old craters.
They then assembled virtual rocks, made of several combinations of ores, to calculate how fast the sound waves were going to cross them. “Diamond, in many ways, is special,” says Faul. “One of its properties is that its speed of sound is more than twice as fast as in the dominant ore in the upper mantle rocks, olivine.”
The scientists then discovered that the only type of rock that corresponded to the speeds they detected in the craton contained 1 to 2% of diamonds. Researchers now believe that old underground rocks contain at least 1,000 times more diamonds than previously believed. These precious stones are however not close to making their arrival in jewelry.
Made of Carbon, diamonds are formed under extreme pressure and extreme temperature in the deepest part of the Earth, and emerge near the surface only through volcanic eruptions that occur only rarely.