Earth’s diamond treasure trove
A new study has found that a quadrillion tons of diamonds might lie deep below the Earth’s surface—so deep that they’re unlikely to ever be dug up. The gems are embedded in cratons, the oldest chunks of rock within the planet’s tectonic plates. Shaped like inverted mountains, cratons can extend 90 to 150 miles through the Earth’s crust. While studying sound waves that course through Earth’s surface after a seismic event, scientists at the Massachusetts Institute of Technology noticed that these waves speed up dramatically when passing through the cratons’ lower tips, known as their roots. To explain this anomaly, the researchers built a 3-D model of virtual rocks and compared the velocity of sound waves traveling through different combinations of minerals. Sound travels twice as fast through diamonds as through other rocks, and the team calculated that cratonic roots are 1 to 2 percent diamond, about a quadrillion tons, meaning the Earth contains 1,000 times more diamond than previously thought. “This shows that diamond is not perhaps this exotic mineral,” research scientist Ulrich Faul tells USA Today. The finding won’t spark a modern-day gold rush, since the world’s deepest borehole goes down only 7.5 miles.