Ringwoodite is a silicate mineral that can be made up of as much as 2.6 percent water by weight. That water isn't stored as a liquid in the rock. Instead, it's present as molecules of hydrogen and oxygen. But when ringwoodite is exposed to very specific temperatures and pressures, the rock can sort of "sweat" water.
Ringwoodite is important because scientists are beginning to learn a lot about the role it plays deep within the Earth. The first natural (as in, not made in a lab) ringwoodite was discovered inside a diamond — research that was published last March. Now, other scientists have found evidence suggesting that there's a whole layer of ringwoodite in Earth's mantle — a layer that could serve a source of water for our oceans.
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