[meteorite-list] Meteoritic Quasicrystals: Secret Diaries, Smugglers and KGB Agents; Oh My!
You would think if carbonaceous chondritic asteroids could make crystals with 10-fold rotational symmetry, they could make something like RNA too? http://physicsworld.com/cws/article/news/2012/aug/13/further-proof-of-extraterrestrial-origin-of-quasicrystalsFurther proof of extraterrestrial origin of quasicrystalsAn international team of researchers has found nine new samples of naturallyoccurring quasicrystals. The work also provides further proof thatquasicrystals were delivered to the Earth by a meteorite. The team'sdiscovery challenges our understanding of both crystallography andsolar-system formation.Conventional crystal structures are made of atoms, or clusters of atoms,that repeat periodically. These patterns are normally restricted to two,three, four or sixfold rotational symmetry - the numbers corresponding tohow many times the crystal appears the same during a rotation through 360°.For a long time these were considered hard and fast rules, and no crystalsthat broke these conditions were thought to exist.Ordered, but not periodicHowever, Israeli physicist Daniel Shechtman found just such a rule-breakingcrystal in 1984 and was awarded the 2011 Nobel Prize for Chemistry for hisefforts. Shechtman had discovered a quasicrystal - a crystal that, whileordered, does not contain structures that repeat periodically. Schectman'scrystal also had 10-fold rotational symmetry. Even after his discovery,there was a lot of scepticism about the existence of such a material. But asthe years went by, other physicists began to construct quasicrystals oftheir own and now more than 100 different types have been found. These,however, are synthetic and have been created under precisely controlledlaboratory conditions. Just as it was originally assumed that quasicrystalscould not exist, after their discovery it was assumed that they could notexist naturally in the wider world.That assumption was called into question in 2009 when Princeton University'sPaul Steinhardt - the man who originally coined the term quasicrystal -appeared to have discovered a naturally occurring variety in a rock samplefrom Russia. Steinhardt and his colleague Luca Bindi, from the University ofFlorence, Italy, measured the ratio of oxygen isotopes within the sample andtheir results suggested that the rock belongs to a class of meteorites knownas carbonaceous chondrites. Not only did this rock contain a naturallyoccurring quasicrystal, it also came from outer space.Thrilling pastBut the scepticism that had followed quasicrystals around since theirdiscovery continued. The rock sample was traced back to Valery Kryachko, aRussian who in 1979 had been panning for platinum in a stream flowingthrough the Koryak mountains in far-eastern Siberia. The rock had somehowturned up in Bindi's museum collection in Italy. People were sceptical ofthe rock's back story as the tale of how it got to Florence involves secretdiaries, smugglers and KGB agents, Steinhardt told physicsworld.com.The only way to settle the debate was to take a shot at finding moresamples, Steinhardt explains. He put together a team of 10 scientists, twodrivers and one cook and set out on a four-day expedition across Siberiaback to the stream where Kryachko had found the original sample. Once there,they panned 1.5 tonnes of sediment from the stream bank, eventuallyisolating a few kilograms for analysis.After six weeks of painstaking grain-by-grain analysis, they hit onsomething special. We found a grain with a fleck of metal on it. Not onlydid it contain quasicrystals, but the oxygen-isotope ratio was exactly thesame [as the original sample], says Steinhardt. It was an incrediblemoment. Out in the field, no-one bet on a more than 1% chance ofsuccessfully finding anything, he adds. The team isolated a total of ninequasicrystal samples. It is thought these samples all come from the samemeteorite, and analysis of the sediment layers suggests it landed within thelast 15,000 years.Extreme formationAs the quasicrystals come from a carbonaceous-chondrite meteorite, they musthave formed in the earliest days of the solar system. Carbonaceouschondrites are thought to have collided together to form the cores of therocky planets, and so Steinhardt's quasicrystals are older than the Earthitself. However, current models cannot account for the presence of thesequasicrystals. We need a novel kind of geological process to form them andso it challenges our ideas of solar-system formation, Steinhardt says.The intense conditions present in the solar system's youth also challengethe prevailing view of quasicrystals as objects that need a carefullycontrolled laboratory set-up to produce. Quasicrystals are not the delicatematerials previously thought. The ones we found must have been formed underrobust and hardy conditions in the early solar system, Steinhardt says.Others agree that the world of quasicrystals could be changed by this10-fold increase in the number of known naturally
Re: [meteorite-list] Meteoritic Quasicrystals: Secret Diaries,Smugglers and KGB Agents; Oh My!
Let me try that again: http://physicsworld.com/cws/article/news/2012/aug/13/further-proof-of-extraterrestrial-origin-of-quasicrystals Phil Whitmer - Original Message - From: dorifry dori...@embarqmail.com To: meteorite central meteorite-list@meteoritecentral.com Sent: Tuesday, August 14, 2012 10:58 AM Subject: [meteorite-list] Meteoritic Quasicrystals: Secret Diaries,Smugglers and KGB Agents; Oh My! You would think if carbonaceous chondritic asteroids could make crystals with 10-fold rotational symmetry, they could make something like RNA too? http://physicsworld.com/cws/article/news/2012/aug/13/further-proof-of-extraterrestrial-origin-of-quasicrystalsFurtherproof of extraterrestrial origin of quasicrystalsAn international team ofresearchers has found nine new samples of naturallyoccurring quasicrystals.The work also provides further proof thatquasicrystals were delivered to theEarth by a meteorite. The team'sdiscovery challenges our understanding ofboth crystallography andsolar-system formation.Conventional crystalstructures are made of atoms, or clusters of atoms,that repeat periodically.These patterns are normally restricted to two,three, four or sixfoldrotational symmetry - the numbers corresponding tohow many times the crystalappears the same during a rotation through 360°.For a long time these wereconsidered hard and fast rules, and no crystalsthat broke these conditionswere thought to exist.Ordered, but not periodicHowever, Israeli physicistDaniel Shechtman found just such a rule-breakingcrystal in 1984 and wasawarded the 2011 Nobel Prize for Chemistry for hisefforts. Shechtman haddiscovered a quasicrystal - a crystal that, whileordered, does not containstructures that repeat periodically. Schectman'scrystal also had 10-foldrotational symmetry. Even after his discovery,there was a lot of scepticismabout the existence of such a material. But asthe years went by, otherphysicists began to construct quasicrystals oftheir own and now more than100 different types have been found. These,however, are synthetic and havebeen created under precisely controlledlaboratory conditions. Just as it wasoriginally assumed that quasicrystalscould not exist, after their discoveryit was assumed that they could notexist naturally in the wider world.Thatassumption was called into question in 2009 when Princeton University'sPaulSteinhardt - the man who originally coined the term quasicrystal -appearedto have discovered a naturally occurring variety in a rock samplefromRussia. Steinhardt and his colleague Luca Bindi, from the UniversityofFlorence, Italy, measured the ratio of oxygen isotopes within the sampleandtheir results suggested that the rock belongs to a class of meteoritesknownas carbonaceous chondrites. Not only did this rock contain anaturallyoccurring quasicrystal, it also came from outer space.ThrillingpastBut the scepticism that had followed quasicrystals around sincetheirdiscovery continued. The rock sample was traced back to ValeryKryachko, aRussian who in 1979 had been panning for platinum in a streamflowingthrough the Koryak mountains in far-eastern Siberia. The rock hadsomehowturned up in Bindi's museum collection in Italy. People weresceptical ofthe rock's back story as the tale of how it got to Florenceinvolves secretdiaries, smugglers and KGB agents, Steinhardt toldphysicsworld.com.The only way to settle the debate was to take a shot atfinding moresamples, Steinhardt explains. He put together a team of 10scientists, twodrivers and one cook and set out on a four-day expeditionacross Siberiaback to the stream where Kryachko had found the originalsample. Once there,they panned 1.5 tonnes of sediment from the stream bank,eventuallyisolating a few kilograms for analysis.After six weeks ofpainstaking grain-by-grain analysis, they hit onsomething special. We founda grain with a fleck of metal on it. Not onlydid it contain quasicrystals,but the oxygen-isotope ratio was exactly thesame [as the original sample],says Steinhardt. It was an incrediblemoment. Out in the field, no-one beton a more than 1% chance ofsuccessfully finding anything, he adds. The teamisolated a total of ninequasicrystal samples. It is thought these samplesall come from the samemeteorite, and analysis of the sediment layerssuggests it landed within thelast 15,000 years.Extreme formationAs thequasicrystals come from a carbonaceous-chondrite meteorite, they musthaveformed in the earliest days of the solar system. Carbonaceouschondrites arethought to have collided together to form the cores of therocky planets, andso Steinhardt's quasicrystals are older than the Earthitself. However,current models cannot account for the presence of thesequasicrystals. Weneed a novel kind of geological process to form them andso it challenges ourideas of solar-system formation, Steinhardt says.The intense conditionspresent in the solar system's youth also challengethe prevailing view ofquasicrystals as objects
