Every breath you take contains a tiny bit of neon, the gas that makes signs in Las Vegas and on Broadway glitter so enticingly, since it makes up 0.0018 percent of the Earth's atmosphere. But just like argon, another of the noble, or inert, elements, neon is similarly inhaled and exhaled by the Earth itself.
As an article published in Proceedings of the National Academy of Sciences details, neon continually cycles from the atmosphere down through the Earth surface to the mantle, and then back to the surface again. But the time interval is a whole lot longer than your breathing.
Argon and neon are noble gases that have been around since our solar system formed 4.6 billion years ago, from a vast cloud of gas and dust. The Earth formed from an accumulation of gas, dust, and small planetary objects. Because noble gases are chemically inert at conditions relevant to processes on Earth, they don't react with other elements.
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"The fact that the noble gases don't react with other elements makes them excellent tracers for understanding the geochemical evolution of Earth and its atmosphere," explains Syracuse University earth sciences professor Suzanne Baldwin, who co-authored the article with Jayeshkumar Das, a research associate, in a press release.
Though noble elements such as neon and argon are notoriously stable and resistant to forming compounds with other elements, they do form isotopes, which have varying numbers of neurons, and neon and argon isotopes are slightly different deep in the Earth than they are in the atmosphere.
"Measuring the isotopic composition and concentrations of argon and neon trapped in new minerals that have formed at mantle depths can help us to understand where these noble gases originated," Baldwin says. "When the minerals crystallized in the mantle, they trapped atoms of argon and neon within them."
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Those minerals get from the mantle to the surface - and from the surface, back into the Earth, via subduction, which is when one of the moving plates that form the Earth's crust slides beneath another plate and goes into the mantle. When the minerals come back to the surface, the process is known as exhumation.
Baldwin's team discovered an area in Papua New Guinea that had been through just such a subduction-exhumation cycle. They determined that some of the minerals, now found at the surface, formed at ultra-high pressure, approximately 8 million years ago, at depths greater than 55 miles (90 kilometers), or roughly the distance from New York City to Philadelphia.
Live Science provides these fascinating facts about neon. In addition, here's a Scientific American article explaining how neon lights work.