Scientists found a diamond that could settle the dispute whether the Earth's mantle holds water or not.
The diamond, which has no commercial value to its very bad shape, has a tiny amount of an olivine compound call ringwoodite. Ringwoodite forms in areas where pressure is extreme, and this is the first time that it has been found on elements other than meteorites.
Researchers have been working to discover what lies beneath the Earth's mantle and the discovery of this rare diamond sheds a new light on that problem. Laboratory tests reflect that olivine undergoes changes depending on the depth from which it was discovered. The difference in the olivine's makeup also explains why seismic waves tend to change their speeds while passing through the depths of the mantle. The researchers also concluded that at 320 to 410 miles deep, olivine becomes ringwoodite.
The recently found diamond from Brazil confirms this theory. At that depth, olivine transforms into a ringwoodite and these could be found at the mantle transition zone. The ringwoodite has 1.5 percent water content on the form of hydroxide ions, suggesting that there could be water from its source.
"It's actually the confirmation that there is a very, very large amount of water that's trapped in a really distinct layer in the deep Earth," lead study author and a geochemist at the University of Alberta in Canada, Graham Pearson told LiveScience.
The diamond was brought into surface by a volcanic eruption. This eruption is called a kimberlite, and Pearson explained that the kimberlite eruptions are like dropping Mentos candies on a glass of soda; it's fast and very forceful.
The discovery of the ringwoodite in the diamond is serendipity, as Pearson and his team initially aimed to find out the diamond's age. According to Pearson, careful handling should be done in studying ringwoodite because changing temperatures can cause the olivine to also alter its form.
"We think it's possible ringwoodite may have been found by other researchers before, but the way they prepared their samples caused it to change back to a lower-pressure form," Pearson told LiveScience.
This study was published in the March 13 issue of Nature.
