It is the most coveted mineral, and also the most resistant on Earth, a symbol of luxury and the power of the more affluent classes.
We know that diamonds are hidden under the surface of the Earth, and also that they exist outside of our planet (as on Neptune, where small pieces of diamond rain down). What we did not know is that the interior of the Earth would be filled with such a quantity: ten thousand trillion tons of diamonds, that is, 10 raised to 16 tons.
Does this mean that this beloved mineral might not be as special as previously thought, and therefore lose its value?
No, since these diamonds are unattainable: they are found 145 to 240 kilometers below the Earth’s surface , in the “roots” of cratons, which are large sections of rock.
Cratons lie beneath most continental tectonic plates and have barely moved since ancient times, as an MIT statement describes.
Those responsible for this discovery belong to several universities around the world, and they noticed the ostentatious hiding place by observing the seismic waves under the Earth.
Because these vibrations can change, based on the composition, temperature and density of the rocks, researchers can use these recordings to build an image of the Earth’s interior.
This is how they discovered that underground vibrations, produced by natural processes such as earthquakes and tsunamis, tended to accelerate when they passed through cratonic roots ; the acceleration was greater than expected due to the fact that the cratons tend to be cooler and less dense than the surrounding structures. This was indicative of a presence that the researchers were ignoring.
The team created a three-dimensional model of the speeds of the seismic waves that traveled through the major skulls of the planet. Then, they created “virtual rocks” from various combinations of different minerals and calculated how fast seismic waves would travel through those rock compositions.
Eventually, they concluded that the best explanation for the observed speeds underground, which differed from what they had predicted, was that 1 to 2% of the roots of the cratons were made up of diamonds , while the rest were made up of diamonds. of peridotite (the main type of rock in the upper mantle of the Earth) and some rocks of the oceanic crust.
“When waves pass through the Earth, diamonds transmit them faster than other rocks or minerals that are less rigid,” explains Joshua Garber, a postdoctoral student at UC Santa Barbara and lead author of the study.
The explanation of the diamonds is one of the possible ones to explain this mystery, but it is not the only one. Therefore, scientists are not sure that this assumption is true.
Other researchers have suggested alternative, but more unlikely, explanations: perhaps, these cratonic rocks are colder than the scientific literature suggests, which means that the rock will be stiffer and therefore seismic waves will travel faster through of them, even if they are not diamond.
In any case, it is exciting to see how our understanding of the depths of the Earth continues to advance.