In 2009, scientists made a groundbreaking discovery that was ultimately traced to a remote corner of the world. In a box obtained from the Italian Mu
In 2009, scientists made a groundbreaking discovery that was ultimately traced to a remote corner of the world. In a box obtained from the Italian Museum of Natural History in Florence, Italy, they found a small grain of extraterrestrial mineral that was formed shortly after the birth of our solar system, 4.5 billion years ago. The mineral came from an area near the Koryak Mountains in eastern Siberia, and was delivered to Earth by an object known as the Khatyrka meteorite. The latter was discovered only after researchers returned to the area in search of more exotic minerals in 2011.
This new rock has been designated as a quasicrystal, in recognition of its unique structural properties. A quasicrystal looks like a normal crystal on the outside, but on the inside it is noticeably different. While the atoms in a pure crystal are arranged in constantly repeating patterns, the atomic lattices inside the quasicrystal are both ordered and diverse, displaying a range of shapes never before seen in a natural substance.
More than 100 synthetic versions of these minerals have been produced in laboratories, between 1982 and the present day. Until these experiments, such a form of matter had never been seen before, and in the past had been believed to be theoretically impossible according to accepted ideas about the laws of nature. Previously the only thing ever found were crystals, with their rigidly repetitive patterns, and so-called normal solids, which are comprised of atoms arranged in no particular order.
A Scientific Detective Story
Even after quasicrystals were created in a laboratory, their existence in nature was doubted. But one of the people who’d predicted that quasicrystals might actually be makeable, Princeton University theoretical physicist Paul Steinhardt, was determined to leave no stone unturned (figuratively and literally) in his search for quasicrystals formed by the processes of nature .
It was Steinhardt who was responsible for finding the quasicrystal sample in the box from the Italian museum, with assistance from an Italian geologist named Luca Bindi. Steinhardt formed a team of scientists to study this intriguing mineral, and they eventually confirmed the unique structure of the tiny rock from one of the planet’s remotest areas.
To uncover the true origin of the quasicrystal sample, the team of scientists investigated numerous possibilities. They tried to develop a realistic scenario explaining how the quasicrystal could have formed naturally on Earth. But in the end, they were able to establish with near 100-percent certainty that it had arrived on Earth from somewhere else in the solar system.
Steinhardt’s analysis showed the mineral was embedded in another mineral known as stishovite. This rock comes from meteorites, and its encirclement of the quasicrsytal meant both minerals had been formed by a high-pressure process at approximately the same time inside a meteorite that eventually landed in the wilds of Siberia. Further cementing their conclusion was the discovery that the ratio of oxygen isotopes inside the quasicrystal was not consistent with ratios found on Earth, but was instead explainable only if the quasicrystal had been created off-planet.
“The finding is important evidence that quasicrystals can form in nature under astrophysical conditions, and provides evidence that this phase of matter can remain stable over billions of years,” Steinhardt explained after announcing the results of his team’s analysis.
Not content with finding just one quasicrystal, Steinhardt and associates made their own trip to Siberia in 2011. After searching the Kamchatka Peninsula area near the Koryak Mountains, they were able to obtain a fresh sample of rock from the Khatyrka meteorite, and inside they eventually found two more quasicrystals , each of which had a unique molecular structure. Since quasicrystals are extremely small the hunt for them is a bit like searching for a needle in a haystack, and the most recently discovered sample was only uncovered in 2016, five years after the meteorite sample was removed from Siberia.
All three quasicrystals were found to contain a mixture of aluminum, copper and iron. The third quasicrystal discovered has a special structure that has yet to be created in synthetic form in a laboratory, highlighting nature’s persistent habit of producing more novelty than we expect or imagine to be possible.
As for the source of the naturally-formed quasicrystals, Steinhardt speculates that a violent collision between two asteroids in the early days of the solar system may have created these remarkable minerals. Close study of their characteristics, and other materials in the Khatyrka meteorite sample retrieved, could help physicists and geologists determine more about what conditions were like when the solar system was in its formative stage.
Quasicrystals possess an interesting package of characteristics. They are extremely hard, but they are also slippery to the touch and do not generate much friction.
So far, the search for useful applications has yielded only a few results, even though researchers have been working with synthetic samples for more than three decades. Quasicrystal has been used to harden the steel from which surgical and other medical instruments are manufactured, and Steinhardt himself invented a quasicrystal-lined frying pan that has some impressive no-stick qualities. But as of now, that’s about it.
Nevertheless, hope springs eternal.
As explained by Paul Asimov, a quasicrystal researcher from the California Institute of Technology, scientists working in this area hope “to find new quasicrystalline alloys that might have some use, because none of the ones discovered so far really have any use other than ‘wow, this is cool. But its not out of the question that someone will find a really good use for quasicrystals one of these days.”
Treasure Troves from the Sky
It is estimated that as much as 100 tonnes of space debris will enter the Earth’s atmosphere each and every day. Most of it will burn up, but a few thousand kilograms of material will actually make it to the Earth’s surface annually.
Few would ever guess that we’re constantly being showered by rocks and dust from the solar system, only a small portion of which will ever be seen or identified.
Which of course bings up a question. Are there other exotic, extraterrestrial forms of matter delivered by meteorites laying around in remote or distant locations, just waiting to be discovered by intrepid scientific explorers? The possibility cannot be ruled out.
At one time, the existence of substances like quasicrystals was considered impossible Other impossible leftovers from ancient times may have landed here as well, brought in on the wings of fiery, glowing chariots of rock. If and when they’re discovered, they may force us to expand our conceptions about the nature of matter.
Top image: An iron meteorite. Credit: Vladimir / Adobe Stock
By Nathan Falde