Thursday, February 11, 2021

The huge reserve of 10 billion tons of diamonds found beneath the Earth’s surface (and how feasible it is to extract them)

There are believed to be 1,000 times more diamonds than previously thought. Today diamonds are a symbol of wealth and elegance, but in the future they may be just an ordinary stone that anyone can have.

That is the scenario one could imagine from a recent study by the Massachusetts Institute of Technology (MIT), which says that 10 billion tons of diamonds accumulate 160 kilometers below the Earth’s surface: that is, a unit followed by 16 zeros (10,000,000,000,000,000).


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"This shows us that diamonds may not be an exotic mineral, if not, on a relatively common geological scale," says Ulrich Faul, one of the authors of the study, in a statement from MIT.


Where are they?


According to researchers, this underground treasure is scattered among gigantic rock formations called cratons.


These cratons are a kind of inverted mountains that lie within most continental tectonic plates, and can extend up to more than 300 kilometers from the Earth’s crust to the mantle.


Diamonds are in rock formations inside the Earth.


"In each craton there are an estimated 1,000 billion tons of diamonds," Ulrich Faul tells BBC World.


"On Earth there are ten geological provinces recognized as cratons, so the total amount of diamonds accumulated in the Earth’s cratons is 10,000 trillion tons".


"Listening" to the diamonds

Researchers have not actually seen the diamonds yet, but they did "hear" them.


Sound waves that occur during an earthquake or volcano eruption travel at different speeds, depending on the composition and temperature of the rocks they pass through.


Thus, by listening to these sound waves, geologists can deduce what kind of material they have passed through.


The researchers used sound waves to calculate the presence of diamonds.


Using that method, the researchers realized that when sound waves passed through the cratons, they traveled much faster than they expected.


With this information they created several rocks in the laboratory, formed by the combination of different minerals and observed in which of them the speed of the wave coincided with the waves they had detected.


The result was that a rock containing between 1% and 2% diamond is the only one that produces the same wave speed that seismologists had recorded.


Depending on the amount and size of cratons, scientists calculated that if each of them has between 1% and 2% of diamonds, that represents the presence of "at least 1,000 times more diamonds than previously expected".


Can you extract them?


For now it is impossible to dig the diamonds, because the cratons that contain them are at least 160 kilometers deep.


To get an idea of what that means, the deepest mine in the world, Mponeng in South Africa, is "only" 4 kilometers deep.


Despite this, the finding is useful to better understand how the interior of the Earth is composed.


"Cratons contain the oldest rocks and minerals on Earth," Faul says. "So they can contain information about how the planet has evolved and the life on it".


"We can’t get to them," says Faul, "but there are still a lot more diamonds than we ever thought".


 

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