Quasicrystals from the edge: extreme environments, impact craters and the quest in other celestial bodies

Quasicrystals, materials with long-range order but no periodicity, were first discovered in nature within the Khatyrka meteorite, a CV3 carbonaceous chondrite. Their occurrence demonstrated that hypervelocity impacts can generate quasiperiodic phases under transient conditions far from equilibrium, which survived for billions of years. Icosahedral and decagonal quasicrystals from Khatyrka formed at pressures exceeding 5 GPa and temperatures above 1200 C, as shown by their microstructures and association with shock-melted silicates and high-pressure polymorphs. Laboratory shock-recovery experiments reproduced these phases, confirming their synthesis during microsecond-scale shock pulses and their persistence after release. The presence of metallic aluminium, rarely stabilized in natural systems, indicates that extreme redox conditions are transiently established during impacts, enabling unusual alloy chemistries. Although rare in the meteoritic record, quasicrystals may be more widespread, their scarcity reflecting preservation biases and limited analytical focus on metallic phases. Advanced nanoscale diffraction and tomography methods, coupled with systematic surveys, are essential to uncover their distribution. Beyond meteorites, terrestrial craters, lunar breccias, Martian meteorites and asteroid samples are promising targets. Quasicrystals thus represent durable witnesses of impact processes, expanding the mineralogical tools for tracing high-energy events that shaped the early solar system.