March 20, 2019 | 28° F

Professor shares story of search for extraterrestrial rocks

Photo by Tian Li |

Professor Paul Steinhardt from Princeton University shared his experiences finding extraterrestrial rocks with quasicrystal structures yesterday at the Physics Lecture Hall on Busch campus.

Not every theoretical physicist finds himself in the desolate regions of Russia in search of valuable extraterrestrial rocks. And even fewer find themselves the subjects of a story involving bears, Soviet smugglers and KGB death threats.

The Department of Physics and Astronomy invited professor Paul Steinhardt from Princeton University to speak Saturday afternoon at the annual Irons Lecture at the Physics Lecture Hall on Busch campus. He discussed his search for a naturally occurring crystal, which led him to discover an alien mineral.

The quasicrystal is a curiosity, said David Vanderbilt, a professor in the Department of Physics and Astronomy.

“Most of the theory is known well by many, but it’s not so often that you get to hear of an adventure,” Vanderbilt said.

Traditional crystals are materials with regular rates and traditional shapes, such as the square, rectangle, parallelogram and hexagon, he said. The determining factor of these quasicrystals is in the regular but differing rates in which their atom patterns repeat.

“If you open a textbook up until the 1980s, one of the first things you learn in chapter one is that there is a certain forbidden symmetry in crystals you’ll never see in nature,” Steinhardt said. “These are the symmetry we see in quasicrystals today.”

Tiling a wall can be done without gaps using many different shapes but never a pentagon. The pentagon has what is called five-fold symmetry, he said. This is the fundamental shape of the quasicrystal.

“The most forbidden symmetry of all the possible shapes in quasicrystals is the icosahedron. It’s a solid with six independent five-fold symmetry axes. It doesn’t violate the five-fold rule once, but six times,” he said.

Five-fold symmetry was supposed to be a closed subject, he said. Since its first successful synthesis, the quasicrystal debate changed from impossibility to natural reoccurrence.

“This is possible in a mathematical representation. So we think, ‘If tiles can do it, why can’t nature do it?’” Steinhardt said.

There was evidence toward natural fabrication, but scientists were not sure, he said.

“You want to know if these quasicrystal materials are robust or delicate,” he said. “All of the laboratory materials were formed under very delicate conditions.”

He said it is unlikely that nature fabricated a quasicrystal on its own, when laboratory synthesis called for very delicate temperature and pressure conditions.

“It is possible that nature’s made them before us, so we may find some that are millions of years old. If not, we have created the first ones. We began to pursue,” he said.

Researchers started with their first set of samples saved in the computer database in Princeton. After three years of slicing, dicing and testing, there was no progress, he said.

After these attempts in 2001, they began looking for help. No response came for six years, he said. But in October 2007, mineralogist Luca Bindi responded.

“We’re lucky, because he immediately became as fanatical about the search as I was. He had things in his collection that were not in our computer database at all. One of them turned out to be a collection of some 10,000 different minerals,” he said.

One of these minerals, named Khatyrkite, would be the driving force of the entire adventure, he said.

“In our sample, Khatyrkite was a material we hadn’t known. The examination revealed the most beautiful pattern I’d seen. This was a quasicrystal and had the same symmetry of the forbidden icosahedron,” he said.

Testing revealed the composition to be 63 percent aluminum, 24 percent copper, and 13 percent iron — exactly that of the first true fabricated quasicrystal. However, they still had no idea how it was formed, he said.

“To find the original source of the sample, all we had was a letter with the original seller of the 10,000 minerals in 1990 and all it had was the name of the collector,” he said.

From there, they found the former head of the Institute of Platinum of Russia, who had moved to Israel, he said.

“His memory of the location was fuzzy, but he was willing to go back to Moscow and look for the sample for $15,000,” he said.

Steinhardt decided not to trust him, but this meant a complete dead end, he said.

“We received death threats from former KGB agents when later seeking help from our guy in Israel,” he said. “He turned out to be involved with smuggling platinum and platinum fakes, which were valuable at the time.”

Following the trail of the late collector’s diary, they looked for the man who, in 1990, found the sample containing the quasicrystal and reported it to the head of the Institute of Platinum at the time as platinum, he said.

He agreed to guide them to the site and help them find more Khatyrkite, he said, and led them to Chukotka, Russia.

“The Russians told us we had to go by truck when there were no roads on Google Earth. They assured us not to worry — we crossed streams and mowed down tall grass in these trucks. It was like a four-day roller coaster ride,” he said.

The trucks were prone to breaking down while millions of mosquitos and numerous bears lurked around, he said.

“We dug out about one and a half tons of materials from up and down the stream. Completely by hand, because using regular shovels would break the material,” he said.

After examination of the oxygen isotopes in the samples, it turned out these icosahedrites in the Khatyrkite were extraterrestrial, forged in the infancy of our solar system, he said.

“It felt like a wonderful affirmation of this entire crazy story that everyone had grains of doubt about. Since then, we’ve found about nine grains of material that we are currently studying. It is a work in progress,” he said.

Colin Marks, a student at Highland Park High School, said he enjoyed the talk very much, and feels it will figure into his future plans.

By Andrew Rodriguez

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