Violent electric fingers striking a sand dune in Nebraska left behind crystals rarely found in nature. Scientists have found a semi-crystalline structure of matter once thought impossible, inside a piece of fulgurite – or “fossilized lightning” – created by a powerful electric shock that enters and combines with the sand. This discovery demonstrates the existence of previously unknown formation pathways of quasi-crystals, which opens new avenues for their synthesis in the laboratory.

“The current work is designed to investigate another possible natural mechanism for the formation of quasi-crystals: electric discharge,” a research team led by geologist Luca Bindi of the University of Florence in Italy said in their paper.

The discovery of a quasi-crystalline in fulgurite with a rarely observed 12-fold symmetry and a previously unreported composition shows that this approach could also hold promise in the laboratory.”

From the humble table salt to the strongest diamonds, most crystalline solids in nature follow the same pattern: their atoms are arranged in a lattice structure that repeats itself in three-dimensional space.

Solids that do not have these repeating atomic structures—amorphous solids like glass—are often atomic jumbles, heaps of atoms mixed together without rhyme or reason. Semicrystals break the rule – their atoms are arranged according to a pattern, but this pattern is not repeated.

When the idea of ​​semi-crystalline first emerged in the 1980s, the concept was thought to be impossible. Solids can be either crystalline or amorphous, not so weird in between. But then scientists discovered them both in laboratory conditions and in nature, in the depths of meteorites.

Since then, scientists have determined that quasi-crystals in nature can only form under extreme conditions with incredibly high shocks, temperatures and pressures. Hyper-velocity meteor strikes are one such place; in fact, for a long time it was the only place they were found in nature, and therefore it was thought to be the only place where they could possibly originate.

Then Bindi and his colleague, Princeton University physicist Paul Steinhardt and his team found a quasi-crystal that had been produced during a nuclear bomb test in 1945. While not exactly “natural” conditions, the discovery suggested that there may be other conditions under which quasi-crystals could form.

Lightning, one of the most powerful forces in nature, strikes at an extraordinary speed and can heat the air it passes through up to 5 times the temperature of the Sun’s surface.

And in the right place, when it hits the ground with enough force, it can melt the sand, leaving a fulgurite – a “fossil” of its path on the ground.

All the components are there: impact, temperature and pressure. So Bindi, Steinhardt and their colleagues set out to study fulgurites for quasi-crystals.

They took a sample of fulgurite from Sandhills, Nebraska, from an area near a downed power line, and subjected it to scanning electron microscopy and transmission electron microscopy to determine its chemical composition and crystal structure.

The sample consisted of molten sand and traces of molten metal conductors from a power line. In it, the researchers discovered a dodecahedral (twelve-sided) quasi-crystal with a previously unknown composition of Mn. _72.3 Si _15.6 cr _9.7 Get _1.8 no _0.6. The atoms in this semi-crystalline formed a structure with 12-fold symmetry arranged in a semi-crystalline arrangement impossible for normal crystals.