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Rule-Breaking Particles May Exist Near the Earth's Core

The earth’s mantle may house strange liquids that defy the rules of chemistry as we know them.

by Caroline Haskins
Nov 16 2018, 2:00pm

Image: Silicates, Wikimedia Commons

Every once in a while, we hear about the horrifying creatures that have been discovered in the deep ocean, which has managed to cement the idea that the deep oceans are the most mysterious, unexplored regions on earth.

Let us propose a more mysterious, completely unexplored region: the core and mantle of the earth. According to research published in Nature on Thursday, the mantle may be home to liquids that defy known rules of chemistry because of the extreme temperatures and pressure exposed to materials in the region.

Per twentieth-century chemist Linus Pauling's third rule of crystal structures, crystals are more unstable when anions (negatively-charged ions) connect with one another by their “faces,” or long sides. He reasoned that anions would want to be as far away from positively-charged cations as possible, meaning that connecting anions by their points is a stable arrangement.

But at extreme temperatures and high amounts of pressure, these researchers proved, this rule is flipped upside down. In fact, eight-sided liquid silicates—molecules of silicon and oxygen that make up most of the earth’s mantle—can arrange themselves such that multiple faces directly connect with each other.

Silicates arranged through shared faces.
Image: Nature

This research could be used to unlock the the chemical evolution of the earth, molecule by molecule. “Modelling of processes involving deep Earth liquids requires information on their structures and compression mechanisms,” the paper reads. “Knowledge on physical and chemical properties of the melts 45 is important for understanding evolution of the deep Earth interiors.

The formation, circulation, and movement of solid and liquid rocks is the one of the biggest forces driving change of earth’s surface conditions. The liquids churning deep below the surface build the earth’s atmosphere, as well as its magnetic sphere, which influences earth’s distribution of gravity and powers human telecommunications.

The researchers used used single-crystal X-ray diffraction diamond anvil cells, which captures the intricate, microscopic structures of crystals. Using those X-ray results, the researchers used computer modeling to simulate to the arrangement of silicate molecules under different amounts of pressure and temperature. Since we can’t actually visit the mantle or core of the earth, computer modeling is necessary in order to understand the composition of particles in the regions.

Scientists have proposed that liquid silicates compress in strange ways under godly amounts of pressure, but prior to now, this face-sharing arrangement of silicates has never been modeled.

The core and mantle of the earth is a growing area of interest for scientists around the world. Earlier this month, researchers from Spain used data from Antarctica’s IceCube observatory in order to link neutrinos—small, difficult-to-detect that are abundant throughout the universe—with the weight and composition of the earth’s inner layers.

Obviously, it would be great to be able to be able to take a tram down to the core and mantle of the earth and gather first-hand silicate data. But if you’ve read or seen Journey to the Center of the Earth, you know that’s a bad (and also impossible) idea, and modeling research like this is the best alternative to the real thing.