Scientists have discovered a strange new form of crystal that was forged in the world’s first nuclear weapons test. Known as a “quasicrystal,” the curious creation is made out of desert sand and copper wiring arranged in an extremely rare atomic structure.
By nature crystals are pedantic rule followers: their atoms line up in highly ordered lattices, forming patterns that repeat in three dimensions. Quasicrystals, however, only got half the memo – their atomic structure is still highly ordered, but they don’t repeat. These strange structures were first discovered in the 1980s and have been created in the lab ever since, in various forms.
Long thought impossible in nature, in 2011 scientists nevertheless discovered quasicrystals in meteorite fragments. These were believed to have formed in a violent collision between two asteroids, which got the team wondering what other energetic processes might create quasicrystals. And few events unleash as much energy as nuclear bomb testing.
“Quasicrystals are formed in extreme environments that rarely exist on Earth,” says Terry Wallace, co-author of the study. “They require a traumatic event with extreme shock, temperature, and pressure. We don’t typically see that, except in something as dramatic as a nuclear explosion.”
So for the new study, researchers from Los Alamos National Laboratory examined material taken from the Trinity Site, the location of the very first nuclear weapons test in 1945. And sure enough, it looks like humans were accidentally creating quasicrystals decades before we discovered them.
The newly identified quasicrystal was found in a sample of red trinitite taken from ground zero, and is made up of silicon, copper, calcium and iron. The silicon comes from the desert sand quickly converted into glass during the blast, while the high copper content seems to have come from the transmission wires used to carry out the test. Material from the test tower itself may also have fused into the bizarre crystal.
More technically speaking, this quasicrystal has 5-fold rotational symmetry, meaning if it’s rotated a full 360 degrees, it will look identical in five orientations along the way. A cube, for example, has 4-fold rotational symmetry – it will look identical from four angles during one full rotation. For a long time, the very definition of a crystal restricted them to 2-, 3-, 4- and 6-fold rotational symmetries.
But the discovery is more than just a scientific curiosity, the team says. Quasicrystals could be used to trace unauthorized nuclear tests, and piece together what happened more accurately.
“We typically analyze radioactive debris and gases to understand how the weapons were built or what materials they contained, but those signatures decay,” says Wallace. “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.”
The research was published in the journal PNAS. The team describes the discovery in the video below.
Source: Los Alamos National Laboratory via Nature