Geologists discover physics-defying “forbidden” crystal at atomic bomb site

At 5:30 A.M. local time on July 16th, 1945, a bomb was detonated in the deserts of New Mexico at a site 210 miles south of Los Alamos, codename Trinity. The intense heat and pressure emanating off the bomb, nicknamed “Gadget,” was enough to not only spark the Atomic Age but to fuse sand and metal infrastructure around it into a green, glass-like material dubbed “trinitite.”

Now, 76-years after that event, a team of geologists from Italy and the U.S. have discovered that Gadget did more than create green trinitite during its explosion — it also created a science-defying crystal that had thus far only been found in meteorites.

This blood-red cousin of trinitite is known as a “quasicrystal.”

“Icosahedral symmetry... is super-forbidden.”

The research describing this discovery was published Monday in the Proceedings of the National Academy of Sciences, and Luca Bindi, the paper’s first author and award-winning geologist from the University of Florence, tells Inverse that this discovery is the culmination of a hunch about the formation of extra-terrestrial crystals.

“It was a surprising discovery,” says Bindi. “[T]he idea behind it was: if these materials can really form in the collision of extraterrestrial objects in outer space, then it is conceivable that they formed also in an atomic blast. And they were there.”

Here’s the background — Crystalline solids — quartz, salt, or diamonds, for example — are bound by pretty strict rules when it comes to how they can form, Bindi explains. These rules are described in a set of principles from the 1980s called “the laws of crystallography.”

“According to these laws, arrangements are either completely random, as in the case of window glass, or crystalline, as is the case for sugar or table salt,” says Bindi. “In the case of crystalline materials, the atoms are organized in a symmetrical lattice like the square tiles in a simple bathroom tiling.”

• Crystals are “allowed” to have rotational symmetries (essentially, points where they can be evenly bisected) along “one-, two-, three-, four- and six-fold symmetry axes.”
• Symmetries along the five, seven, eight, or higher axes are “strictly forbidden,” says Bindi. That’s exactly the kind of structure this new quasicrystal has.

“Icosahedral symmetry, which includes six independent five-fold symmetry axes, is super-forbidden,” says Bindi. “Quasicrystals are solids with these rotational symmetries that are forbidden for crystals.”

What’s new — The authors report in the study that this crystal is the “oldest extant anthropogenic” quasicrystal ever discovered, meaning the oldest existing sample created by human action instead of a cosmic collision, dwarfed in age only by meteorites forged before Earth itself.

“The only known examples of older quasicrystals are the naturally formed quasicrystals discovered in the Khatyrka meteorite that date back at least hundreds of millions of years and perhaps to the beginning of the Solar System,” write the authors.

“Curiously, neither the oldest extant natural nor the oldest extant anthropogenic quasicrystal was made under controlled laboratory conditions.”

Why it matters — While the Trinity site explosion itself is old news, Bindi says there still plenty that scientists can learn from this quasicrystal and the physical limitations of crystals as a whole.

“A quasicrystal that is formed at the site of a nuclear blast can potentially tell us new types of information — and they’ll exist forever,” says Bindi, unlike radioactive decay signatures which decay over time.

Studying quasicrystals can help scientists do everything from reverse engineer explosions to create new age lasers and even discover an alternative to Teflon, Bindi says.

What they did — Before the team could determine that these red trinitite samples were science-breaking quasicrystals, they first had to take a peek inside their atomic structure using a myriad of super up-close imaging techniques including:

• Scanning Electron Microscopy
• Electron Microprobe
• Single-Crystal X-Ray Diffraction

These different techniques helped the team determine the symmetry of these samples as well as how they compared to the green trinitite samples also found at the site. Their analysis also included measurements of radioactivity.

See also: How this massive nuclear site will become a National Park

The confirmation of quasicrystals being formed at the Trinity site is not only evidence that terrestrial environments — like atomic explosions — are capable of creating such materials but that they can last for over 70-years as well.

What’s next — Quasicrystals like this are very rare and aren’t likely going to be fueling the next generation of electronics (or jewelry) anytime soon, but the discovery of this atomic remanent could help scientists better understand how to create such materials under laboratory conditions in the future.

“The newly discovered quasicrystal that was created by the first nuclear explosion at Trinity Site could also someday help scientists better understand illicit nuclear explosions and curb nuclear proliferation,” says Bindi.

Abstract: The first test explosion of a nuclear bomb, the Trinity test of 16 July 1945, resulted in the fusion of surrounding sand, the test tower, and copper transmission lines into a glassy material known as “trinitite.” Here, we report the discovery, in a sample of red trinitite, of a hitherto unknown composition of icosahedral quasicrystal, Si61Cu30Ca7Fe2. It represents the oldest extant anthropogenic quasicrystal currently known, with the distinctive property that its precise time of creation is indelibly etched in history. Like the naturally formed quasicrystals found in the Khatyrka meteorite and experimental shock syntheses of quasicrystals, the anthropogenic quasicrystals in red trinitite demonstrate that transient extreme pressure–temperature conditions are suitable for the synthesis of quasicrystals and for the discovery of new quasicrystalforming systems.

Note: This story has been updated to correct the spelling of trinitite and to clarify the nature of crystalline solids and the analysis techniques used by the researchers. We apologize for the errors and for any misunderstanding caused.