Massive Diamond Cache May Be Hidden 100 Miles Below Earth's Surface

Diamonds are expensive, but not terribly rare. A new report indicates that Earth may have a truly massive cache of them located about 100 miles beneath the Earth's surface, a depth that is too deep for present drilling technologies. The discovery was made using seismic activity data, which revealed an anomaly with sound waves passing faster than expected through part of the Earth's interior.

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The study was detailed by MIT, which explains that seismic activity data gathered by entities like the USGS essentially involves sound waves that pass through the Earth.

Using this data, particularly the speed at which sound waves pass through rocks, scientists are able to piece together an idea of the Earth's interior. A variety of things impact the sound waves, such as a rock's density and temperature.

Using the seismic data, scientists noted that sound waves pass more quickly than expected through ancient cratonic roots, which are shaped like upside-down mountains and found beneath the center of many continental tectonic plates. The roots, in this case, refers to the portion of cratons that span down through the planet's crust and into the mantle.

Researchers noted that though sound waves pass a bit more quickly in cratons versus the denser, hotter mantle, data shows faster speeds than expected. A virtual model of the structure was created and different mineral compositions were used to discover which could account for the sound wave data. A composition that contains 1% – 2% of diamond fits the bill; this could amount to a quadrillion tons.

Talking about the study is MIT research scientist Ulrich Faul:

This shows that diamond is not perhaps this exotic mineral, but on the [geological] scale of things, it's relatively common. We can't get at them, but still, there is much more diamond there than we have ever thought before.