There might be a quadrillion tons of diamonds trapped deep under the earth

The study, which was based on decades' worth of seismic activity data, was published in the year 2018 in the journal Geochemistry, Geophysics, Geosystems.

Seismographers record the waves produced by all types of tectonic movements, including earthquakes. Mechanical waves, move at different rates based on the substance they pass through. The researchers attempted to rebuild the interior of the Earth using the data, and it was during this process that they made an intriguing discovery.

They discovered several regions where the seismic waves had an irrational tendency to accelerate. These areas are known as "cratonic roots" and are the oldest, most stable segments of continental tectonic plates. They can reach a depth of 320 kilometers (200 miles), giving the impression that they are mountains that are upside down.

The scientists began experimenting with the potential makeup of these roots in an effort to explain the seismic data. They came to the conclusion that the seismic wave speed makes sense if these structures include between 1 and 2 percent diamond.

In comparison to the entire quantity of material in the crust and mantle, this may not seem like much, but the amount of diamonds is 1,000 times more than anticipated. "This shows that diamond is not perhaps this exotic mineral, but on the [geological] scale of things, it's relatively common," Dr. Ulrich Faul, senior author from MIT, said in a statement in 2018.

Dr. Faul said, "There is still far more diamond there than we had ever realized previously, even if we can't get at them. Faul continued, "It's circumstantial evidence, but we've put it all together. "We looked at every possible scenario from every angle, and this is the only one that makes sense," the author writes.

Under very high pressure and temperature conditions found below the Earth's crust, diamonds are produced. They are uncommon because they only get near the surface during particular eruptions that form kimberlite-based geological pipelines. Therefore, the idea that there may be a significant population of them deep below the crust is not too far-fetched.

Diamonds grow under high pressure and temperature conditions, usually deep below the Earth's mantle, around 150 to 200 kilometers (93 to 124 miles) below the surface. This area is known as the diamond stability zone. Because shallower deposits, such as volcanic pipes or alluvial deposits are more accessible, the bulk of diamond mining operations now harvest diamonds from them.

The quadrillion tons of diamonds estimate is hypothetical and based on theoretical theories of Earth's composition and diamond production. According to these theories, the mantle contains huge amounts of carbon, the fundamental ingredient of diamonds. However, even if such large numbers of diamonds are there, the scientific and logistical obstacles to extracting them are considerable.

The great depths at which these gems are found make access to them now impossible. Furthermore, the expense and feasibility of drilling to such depths, the severe mantle conditions, and the immense time scales necessary for diamond creation make extraction of these diamonds exceedingly problematic.

It's worth mentioning that the majority of natural diamonds used in jewelry and industrial uses come from more accessible resources like mines or alluvial deposits. These resources have proven to be commercially feasible, and they have long been the focus of diamond mining. To summarize, while large numbers of diamonds may exist deep beneath the Earth's surface, their extraction is currently neither practicable nor economically sustainable. The phrase you cited represents the theoretical abundance of diamonds but does not indicate that these gems are easily accessible or usable.