Diamond brings deep Earth crystal to the surface

Called davemaoite, this long-predicted substance was found trapped inside a diamond from over 600 kilometres below the planet's surface
deep earth crystal The new crystal—davemaoite—found within a deep earth diamond. (Aaron Celestian, Natural History Museum of Los Angeles County)

Science has given us all sorts of incredible predictions. Take black holes, for instance, a deep space phenomenon that had been guessed by Albert Einstein as far back as 1915—decades before humans even found a way to leave the planet!

But if predictions are one thing, then proof is another. Those black holes? We didn't actually get visual confirmation (a.k.a. a photo) of one until a couple years ago! That's over a century of waiting. The bottom line is that getting proof of some things is extremely hard. You need to wait for new innovations, apply a lot of patience, and hope for a bit of luck.

Luck, like, say, the earth spitting up a diamond from hundreds of miles below the surface that just happens to contain a crystal predicted to exist 50 years ago!

Sounds like science fiction, right? But this is exactly what happened. Read on!

Diamond from the deep Earth

The diamond in question was found in Botswana, South Africa. It was formed in the lower mantle of the planet. That's really deep down—in this case, at least 660 kilometres (410 miles) down! Deep earth diamonds, as they are known, aren't necessarily that uncommon. After all, immense pressure is what makes a diamond, and there's a lot of pressure that far underground.

But what makes this diamond special is that it contains something extra inside—a new type of crystal calcium silicate (CaSiO3). One that they have named davemaoite, after the geologist who predicted it would exist, Ho-Kwang (Dave) Mao!

What makes finding davemaoite so special? Read on...

Dave's crystal

Geologists like Mao had long predicted that this type of crystal would exist in the lower mantle. In fact, they estimated that it is so common there that it is the fourth most abundant mineral in the Earth!

But here's the problem. It requires such an incredible amount of pressure to make davemaoite, that it can only happen in places like the lower mantle—places that are impossible for us to ever visit. (The deepest hole ever drilled on Earth was about 7 km (4.3 miles), over 650 kilometres away from where the Earth's lower mantle even begins.) They can't exist higher up on Earth. The pressure just isn't strong enough to make them.

But by being trapped within a diamond —one of the strongest substances known—that just naturally, over time, traveled up from the deep mantle, this davemaoite was able to hitch a ride!

Scientists are excitedly studying it to learn as much as they can about conditions deep inside our planet. Amazing!

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