To prove the assumption that quasicrystals are energetically stable like crystalline minerals, they should as well occur outside the laboratory under natural processes without any human interaction. This conjecture led to the search for examples of natural occurrences of quasicrystals. Prof. Dan Schechtman, the discoverer of the quasicrystals, and his team analyzed a sample of the collections of the Museo di Storia Naturale di Firenze (Italy) named “Khatyrkit”, after the river “Khatyrka” in Chukotka in far eastern Russia, where they found the mineral. It is a metallic crystal phase of copper and aluminum and, like the synthetic quasicrystals comprises metallic aluminum. The diffraction pattern of the transmission electron microscope approved that the sample had the accurate appearance of an icosahedral quasicrystal.So far, only three natural occurrences of such quasicrystals have been discovered, and all originate from the Khatyrka region in Siberia.
Still, the sample didn’t exclude the possibility that synthetic byproducts contaminated the sample from the collection. Further investigations on the sample showed that the quasicrystal was confined in stishovite, a rare polymorph of SiO2 (silicon dioxide) formed at 1.200 degree Celsius by an ultrahigh pressure of 5 GPa. This pressure is more than 50.000 times of atmospheric one, i.e. around 50.000 bar. This knowledge excluded the fact that the sample was synthetic, but led to the next question of which natural environment could meet these extreme requirements. There were only two possibilities, first, that the quasicrystal was disgorged onto the surface in a superplume, an up-stream of hot rock material from the core-mantle boundary of the earth, or that the quasicrystal was a result of a violent collision of meteorites in space.
They tested the exceptional sample on the ratio of oxygen isotopes to determine if it was terrestrial or extraterrestrial. The resulting measurements coincided with the values of found calcium aluminum-rich meteorites formed in the earliest moments of the solar system. This meant that the materialization of quasicrystals already dated back 4.5 billion years. Quasicrystals, as one of the oldest minerals known, in the form of extraterrestrial meteorites had an influence on the composition of further minerals and even on the formation of planets in our solar system. It is the quasi-crystalline order that dominates the structure of the mineral, which under the conditions prevailing in the world cannot arise and therefore does not come from this planet.
floating meteor from outer space
extraterrestrial space configuration with parallel structures