Diamantes e mais diamantes

A "apenas" 160Km:
https://news.sky.com/story/scientists-discover-quadrillion-tons-of-diamond-beneath-earths-surface-11439278

Citando:
""Diamond in many ways is special," Dr Faul said. "One of its special properties is that the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine."

Unfortunately for diamond hunters, the minerals are buried more than 160km (100 miles) beneath the Earth's surface - far deeper than any human drills have ever reached.

Dr Faul and his team discovered that sound was moving much faster than it could have been expected to within sections of rock known as cratonic roots.

Cratons are the oldest sections of rock beneath that usually lie beneath continental tectonic plates, and their roots - shaped like inverted mountains - stretch up to 200 miles beneath the Earth's surface."