This battered diamond has survived a "journey to hell and back," and it has a pretty specular story to tell. Spat out from deep inside the earth, it is our first direct evidence for a scientific theory that says that vast amounts of water are trapped deep inside Earth's mantle.
Discovered by miners who thought it was worthless, the diamond could be key for our understanding of our planet. Becky Oskin at Livescience explains:
The diamond from Brazil confirms that the models are correct: Olivine is ringwoodite at this depth, a layer called the mantle transition zone. And it resolves a long-running debate about water in the mantle transition zone. The ringwoodite is 1.5 percent water, present not as a liquid but as hydroxide ions (oxygen and hydrogen molecules bound together). The results suggest there could be a vast store of water in the mantle transition zone, which stretches from 254 to 410 miles (410 to 660 km) deep.