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Abstract We report the discovery of (Al,Cu)‐bearing metallic alloys in two micrometeorites found in the Project Stardust collection gathered from urban rooftop environments in Norway. Most of the alloys are the same as those found in the Khatyrka meteorite and other micrometeorites, though one has a composition that has not been reported previously. Oxygen isotope ratio measurements using secondary ion mass spectrometry show that the Project Stardust samples reported here, like all earlier examples of natural (Al,Cu)‐bearing alloys, contain material of chondritic affinity. 

Experiments on shock amorphization of plagioclase in Mars-like basalt reconcile the pressure scale for martian meteorites. 

We report the discovery of a dodecagonal quasicrystal Mn 72.3 Si 15.6 Cr 9.7 Al 1.8 Ni 0.6 —composed of a periodic stacking of atomic planes with quasiperiodic translational order and 12-fold symmetry along the two directions perpendicular to the planes—accidentally formed by an electrical discharge event in an eolian dune in the Sand Hills near Hyannis, Nebraska, United States. The quasicrystal, coexisting with a cubic crystalline phase with composition Mn 68.9 Si 19.9 Ni 7.6 Cr 2.2 Al 1.4 , was found in a fulgurite consisting predominantly of fused and melted sand along with traces of melted conductor metal from a nearby downed power line. The fulgurite may have been created by a lightning strike that combined sand with material from downed power line or from electrical discharges from the downed power line alone. Extreme temperatures of at least 1,710 °C were reached, as indicated by the presence of SiO 2 glass in the sample. The dodecagonal quasicrystal is an example of a quasicrystal of any kind formed by electrical discharge, suggesting other places to search for quasicrystals on Earth or in space and for synthesizing them in the laboratory. 

Icosahedral quasicrystals (i-phases) in the Al–Cu–Fe system are of great interest because of their perfect quasicrystalline structure and natural occurrences in the Khatyrka meteorite. The natural quasicrystal of composition Al 62 Cu 31 Fe 7 , referred to as i-phase II, is unique because it deviates significantly from the stability field of i-phase and has not been synthesized in a laboratory setting to date. Synthetic i-phases formed in shock-recovery experiments present a novel strategy for exploring the stability of new quasicrystal compositions and prove the impact origin of natural quasicrystals. In this study, an Al–Cu–W graded density impactor (GDI, originally manufactured as a ramp-generating impactor but here used as a target) disk was shocked to sample a full range of Al/Cu starting ratios in an Fe-bearing 304 stainless-steel target chamber. In a strongly deformed region of the recovered sample, reactions between the GDI and the steel produced an assemblage of co-existing Al 61.5 Cu 30.3 Fe 6.8 Cr 1.4 i-phase II + stolperite (β, AlCu) + khatyrkite (θ, Al 2 Cu), an exact match to the natural i-phase II assemblage in the meteorite. In a second experiment, the continuous interface between the GDI and steel formed another more Fe-rich quinary i-phase (Al 68.6 Fe 14.5 Cu 11.2 Cr 4 Ni 1.8 ), together with stolperite and hollisterite (λ, Al 13 Fe 4 ), which is the expected assemblage at phase equilibrium. This study is the first laboratory reproduction of i-phase II with its natural assemblage. It suggests that the field of thermodynamically stable icosahedrite (Al 63 Cu 24 Fe 13 ) could separate into two disconnected fields under shock pressure above 20 GPa, leading to the co-existence of Fe-rich and Fe-poor i-phases like the case in Khatyrka. In light of this, shock-recovery experiments do indeed offer an efficient method of constraining the impact conditions recorded by quasicrystal-bearing meteorite, and exploring formation conditions and mechanisms leading to quasicrystals.