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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. 

Banded iron formations (BIF) are chemically precipitated sediments that can record Archean ocean geochemistry. BIFs are laminated silica- and iron-rich deposits that host a range of iron(II, III) minerals, including hematite, magnetite, siderite, greenalite, minnesotaite, and stilpnomelane. This diverse mineralogical assemblage reflects secondary mineralization reactions due to diagenesis and/or post-depositional alteration. While petrographic observations of BIFs sparingly contain the iron silicate greenalite, recent evidence of greenalite nanoparticles preserved in early-mineralizing BIF chert suggest this mineral was a primary phase in BIF progenitor sediments. Therefore, it is critical to investigate the formation and alteration of greenalite to constrain the Archean ocean environment and help unravel post-depositional processes. To examine how iron silicates precipitate and then crystallize and/or transform during diagenesis, we simulated these two processes under Archean ocean conditions. We first precipitated a poorly ordered Fe-rich serpentine with subsidiary ferrihydrite at neutral pH by performing in situ Fe(II) oxidation experiments at 25 °C in the presence of silica. Subjected to simulated diagenesis at 80 °C, the rudimentary Fe-phyllosilicate transformed into a crystalline phyllosilicate characterized as 30% cronstedtite and 70% greenalite accompanied by magnetite and persistent ferrihydrite. At temperatures ≤150 °C, we continued to observe ferrihydrite, increased magnetite formation, and elevated incorporation of Mg into the phyllosilicate as it further recrystallized into Mg-greenalite. Our findings demonstrate a possible formation mechanism of early silicates through partial Fe(II) oxidation and support petrographic observations that magnetite likely mineralizes during diagenesis. Additionally, we suggest that Mg contents in BIF iron phyllosilicates could serve as a tracer for diagenesis, with Mg signaling phyllosilicate-fluid interactions at elevated temperatures. Ultimately, our experiments help reveal how initial iron-silica coprecipitates are altered during diagenesis, providing novel insights into the interpretation of greenalite and magnetite in ancient BIF assemblages. 

We present a new set of reference materials, the ND70‐series, forin situmeasurement of volatile elements (H₂O, CO₂, S, Cl, F) in silicate glass of basaltic composition. The materials were synthesised in piston cylinders at pressures of 1 to 1.5 GPa under volatile‐undersaturated conditions. They span mass fractions from 0 to 6%m/mH₂O, from 0 to 1.6%m/mCO₂and from 0 to 1%m/mS, Cl and F. The materials were characterised by elastic recoil detection analysis for H₂O, by nuclear reaction analysis for CO₂, by elemental analyser for CO₂, by Fourier transform infrared spectroscopy for H₂O and CO₂, by secondary ion mass spectrometry for H₂O, CO₂, S, Cl and F, and by electron probe microanalysis for CO₂, S, Cl and major elements. Comparison between expected and measured volatile amounts across techniques and institutions is excellent. It was found however that SIMS measurements of CO₂mass fractions using either Cs⁺or O⁻primary beams are strongly affected by the glass H₂O content. Reference materials have been made available to users at ion probe facilities in the US, Europe and Japan. Remaining reference materials are preserved at the Smithsonian National Museum of Natural History where they are freely available on loan to any researcher. 

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

Polymer-derived ceramics (PDCs) which are fabricated through pyrolysis of preceramic polymers have attracted increasing attention due to their versatility in structure architecture design and property tailoring. Shaping at the polymer state using 3D printing allows the final ceramic products to exhibit arbitrary shapes and complex architectures that are otherwise impossible to achieve through traditional processing routes. The polymer-to-ceramic phase transition also provides additional space for mechanical property tailoring. A multiscale computational model is developed to explore the phase transition mechanisms and their correlations with processing parameters and failure response. Calculations in this work concern PMHS/DVB preceramic polymers. Molecular dynamics (MD) simulations are carried out first to track the atomic structure evolution at different temperatures. Continuum-scale ceramic phase formation is calculated on the basis of the competition between gas generation and gas diffusion. The effect of processing parameters on mechanical properties of pyrolyzed PMHS/DVB is systematically studied. Conclusions from this study can provide direct guidance for fabricating PDC composites with tailored mechanical properties. 

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.