The impossible crystals that came from outer space

In the 1980s, Daniel Schechtman theorized the existence of quasicrystals, bizarre materials between crystals and glasses that could never exist except in the laboratory. But now his impossible crystals have turned up in a Russian mountain.

Although chemists initially dismissed quasicrystals as just a theory - and not a particularly good theory at that - Schechtman has had the last laugh and then some, winning the Nobel Prize last year for his work on these exotic materials. Quasicrystals are distinguished from regular crystals by their lack of translational symmetry, which basically means that they have an ordered structure that does not regularly repeat like that of a crystal. That helps give them some rather unusual physical and electrical properties.

Until 2009, quasicrystals were thought to be purely the stuff of laboratory experiments, as they would be too prone to just turn into regular old crystals if they tried to form in nature. That changed with their discovery in the Koryak Mountains in Siberia. An alloy of aluminum, copper, and iron showed clear evidence of naturally occurring quasicrystals. But that raised a tricky question - exactly what sort of previously unknown natural process could create such strange materials?

We don't yet have a good answer to that question, but we can say with some certainty that whatever created them, it happened in deep space. According to new research from Princeton, mass spectrometry has revealed the composition of the minerals is unlike anything found on Earth, suggesting these were likely deposited by meteorites. Also, the silica found in the minerals formed at extraordinarily high pressures, those known only in the Earth's mantle or in an extreme velocity impact, such as when a meteorite smashes into the Earth.

Most likely, the Koryak minerals formed about 4.5 billion years ago during the earliest days of the solar system. There's still plenty we don't know about these exotic quasicrystals, but it now seems that even if they're impossible on Earth, they could be very common out there in space. That's an entire form of matter that can only ever form in space - and it raises the intriguing thought of what other undiscovered types of structures might still be out there in the cosmos.

Via BBC News. Image by Paul Steinhardt, Princeton University.