WASHINGTON – There’s a load of bling buried in the Earth.
More than a quadrillion tons of diamonds to be exact, or one thousand timesmore than one trillion, US researchers at the Massachusetts Institute ofTechnology reported this week.
But don’t expect a diamond rush. These naturally occurring preciousminerals are located far deeper than any drilling expedition has everreached, about 90 to 150 miles (145 to 240 kilometers) below the surface ofour planet.
“We can’t get at them, but still, there is much more diamond there than wehave ever thought before,” said Ulrich Faul, a research scientist in MIT’sDepartment of Earth, Atmospheric, and Planetary Sciences.
“This shows that diamond is not perhaps this exotic mineral, but on thescale of things, it’s relatively common.”
Using seismic technology to analyse how sound waves pass through the Earth,scientists detected the treasure trove in rocks called cratonic roots,which are shaped like inverted mountains that stretch through the Earth’scrust and into the mantle.
These are “the oldest and most immovable sections of rock that lie beneaththe center of most continental tectonic plates,” explained MIT in astatement.
The project to uncover deep Earth diamonds began because scientists werepuzzled by observations that sound waves would speed up significantly whenpassing through the roots of ancient cratons.
So they assembled virtual rocks, made from various combinations ofminerals, to calculate how fast sound waves would travel through them.
“Diamond in many ways is special,” Faul said.
“One of its special properties is, the sound velocity in diamond is morethan twice as fast as in the dominant mineral in upper mantle rocks,olivine.”
They found that the only type of rock that matched the speeds they weredetecting in craton would contain one to two percent diamond.
Scientists now believe the Earth’s ancient underground rocks contain atleast 1,000 times more diamond than previously expected.
Still, very few of these gems are expected to make their way to thejewellery store.
Diamonds are made from carbon and are formed under high-pressure andextreme temperatures deep in the Earth.
They emerge near the surface only through volcanic eruptions that occurrarely, on the order of every few tens of millions of years.