Diamond sample containing the hydrous ringwoodite.

The Earth’s transition zone is the part of the Earth that exists between the upper and lower mantle. Scientists often theorize what lies in the transition zone. Many believe that the transition zone contains a lot of water, but there was no proof to support that idea. A group of geologists from the University of Alberta uncovered a water-containing gem that finally confirms this theory: there is water, possibly massive oceans of it, deep beneath the Earth’s surface.

The tiny gem was an accidental find while the geologists were searching for a completely different mineral. In fact, they very nearly discarded what appeared as a useless brown diamond (because that’s how geologists think of diamonds). This diamond, though, turned out to hold ringwoodite, a mineral we have only previously seen in meteorites, and not on Earth. Fortunately, as with many scientific discoveries, this accident was a happy find. The mineral, which isn’t visible to the naked eye, exists deep within the Earth, at least 300 miles beneath its surface, in the transition zone. Geologists believe that volcanic activity pushed this particular rock up to Earth’s surface.

Having a piece of the Earth’s transition zone available, geologists spent several years testing it. Their final results showed that the gem contained 1.5 percent of its weight in water. This discovery proves the theory that the Earth’s transition zone not only contains water, but might also contain more water than every surface ocean combined. This would make this discovery one of the biggest geological finds in decades.

Because it’s so difficult to dig a hole deep enough to reach even the upper mantle of the Earth (although that hasn’t stopped us from trying), and we can’t guarantee our simulations are accurate, having proof that water exists in the transition zone changes much of what we know about Earth and its composition.

Via Dvice