We discovered a brucite, quartz and moissanite bearing natural rock of mantle affinity containing relics of two now decomposed minerals, so far known from meteorites only, constituting 4 vol

This study re-evaluates the anomalous subgroup of australites known as high Na/K (HNa/K) tektites (Chapman and Scheiber, 1969). Although previous compositional and isotopic analyses suggested a distinct origin, the group has never been formally recognized as a separate tektite strewn field. We present new data from six HNa/K tektites, complementing the eight specimens already described. We conducted a comprehensive investigation, including petrographic (optical and electron microscopy, and micro-X-ray tomography), geochemical (major and trace element compositions, Sr-Nd isotopic composition, 40Ar/39Ar dating), and spectroscopic (for the identification of inclusions) analyses. We concluded that the HNa/K tektites originated from a separate impact event compared to Australasian tektites; they have an andesitic to dacitic composition and arc-related trace element signatures. Lechatelierite (and phosphate) inclusions as well as high levels of chondritic contamination support an impact origin, for which we provide a more precise 40Ar/39Ar age: 10.76 +/- 0.05 Ma. For now, Sr-Nd isotopic data and trace elements composition point to three possible sources associated with active volcanic arcs: Luzon (Philippines), Sulawesi (Indonesia), and the Bismarck region (Papua New Guinea). Systematic petrographic and geochemical differences observed between tektites from the western and eastern parts of the -900-km-wide hypothesized strewn field (located in Southern Australia) may help to constrain the location of the source crater, but they need to be confirmed by the study of more specimens. We propose the name "Ananguite" for this new group of tektites.

Dissociated zircon is largely used as a robust indicator of glasses generated by impact cratering and airbursts. The reaction of zircon dissociation, i.e. ‘ZrSiO 4 → ZrO 2 + SiO 2 ’, requires high temperatures (>1670°C) only reached by extreme geological processes. Using high‐temperature experiments, this study shows that zircon can dissociate and form ZrO 2 ‐rich coronitic rims at temperatures of 900–1000°C (P = 1 bar), in the presence of a specific chemical environment made of NaCl or a mixture of NaCl and caliche soil (Ca‐sulfates). The use of silica glass vessels provides a SiO 2 ‐rich environment during the experiments. We observe that the dissociation is strongly related to the complexity of the surrounding system (e.g. the presence of other minerals that act as a flux) in which the reaction occurs. For these reasons, we suggest considering a more careful approach in using dissociated zircon as indicative of very high temperatures in glass‐forming processes.

CI1 chondrites are rare meteorites with high scientific value. In fact, they are the most chemically primitive meteorites and show evidence of intense parent‐body aqueous alteration. They also share strong similarities with samples from Ryugu and Bennu asteroids returned by the JAXA Hayabusa2 and NASA's OSIRIS‐REx missions. In this work, we present a detailed study of the Oued Chebeika 002 meteorite, a ~420 g CI1 chondrite found in Morocco in 2024. We describe its petrography, texture, and mineralogy, with a focus on clay mineralogy. We provide the bulk and mineral chemical composition, as well as the bulk oxygen, iron, and chromium isotopic compositions. Spectroscopic properties were studied by means of infrared and Raman spectroscopies. We also measured the density, grain density and magnetic properties. Our results confirm that Oued Chebeika 002 is a CI1 chondrite, with close similarities to the other five know CI1 chondrites, and samples from Ryugu and Bennu asteroids. Several lines of evidence indicate that Oued Chebeika 002 has suffered no significant terrestrial alteration. It is more pristine in that regard than Alais, Orgueil and Ivuna CI1 chondrites, and more similar to samples from asteroids Ryugu and Bennu. Subtle differences exist between Oued Chebeika 002 and other CI1 chondrites that cannot be accounted for by terrestrial alteration of the latter. For instance, olivine and calcite were not observed. It is also noteworthy that the magnetic mineral assemblage of Oued Chebeika 002 is significantly different from that of Alais, Ivuna and Orgueil, but undiscernible from that of Ryugu samples. Chromium and iron isotopic composition of Oued Chebeika 002 confirms that CI1 chondrites, like Ryugu samples, are distinct from meteorites belonging to the non‐carbonaceous and carbonaceous isotopic groups and may have originated from the same region where ice giant planets and Oort Cloud comets were formed.

When exposed to high-temperature conditions (~1670°C), zircon crystals (ZrSiO4) decompose according to the reaction: ZrSiO4→ZrO2+SiO2 [2,8]. Under optical and electron microscopes, decomposed zircons are easily identified by the presence of bright rims of baddeleyite (ZrO2) surrounding the unaltered primary crystal core (ZrSiO4). Due to the high temperatures needed for this reaction to occur (i.e., exceeding the highest temperatures normally reached by magmatic processes or wildfires on the Earth’s surface), finding decomposed zircons in natural glass has become a handy unequivocal way to relate natural glass to extreme processes like meteoritical impacts [1], airbursts [6], or lightning [3]. If recognizing fulgurites (i.e., products of lightning) is more easily done because of their morphology, the identification of impact glasses can be problematic, especially when they are not associated with a known impact crater. This work aims to demonstrate the reliability of zircon decomposition as a geothermometer, used to identify impact (or airbursts) glasses.Through high-temperature experiments, we show that the decomposition of zircons can occur in natural systems at lower temperatures than the ones predicted by models. At T=900-1000°C (P=1 bar, exposed to air), in the presence of Ca-sulfates and NaCl-rich soil called ‘caliche’ (from the Atacama Desert, chosen for its relation with one of the most recent debated case, that of Pica glass – [4,5,6,7]), zircons decomposed forming the typical bright rims. Using FEG-SEM-EDS, Raman spectroscopy, and TEM (on thin foils prepared using FIB), however, we show that the Zr-rich rim mineralogy in our experiments differs from previous petrographic descriptions, with assemblages of baddeleyite, baddeleyite + Ca-Zr-oxide, or only Ca-Zr-oxide.In conclusion, we demonstrate that decomposed zircons could also result from lower temperature processes than impacts or airbursts and should be used more carefully in assessing the origin of glasses. Also, we suggest that a more detailed mineralogical characterization of decomposed zircons (rarely done after their detection) is needed to correctly assess the formation conditions of samples containing such rims. References [1] El Goresy A., 1965. Baddeleyite and its significance in impact glasses. Journal of Geophysical Research, 70:3453-3456.[2] Kaiser A., et al., 2008. Thermal stability of zircon (ZrSiO4). Journal of the European Ceramic Society, 28:2199-2211.[3] Kenny G.G. and Pasek M.A., 2021. The response of zircon to the extreme pressures and temperatures of a lightning strike. Scientific Reports, 11:1560.[4] Roperch P., et al., 2017. Surface vitrification caused by natural fires in Late Pleistocene wetlands of the Atacama Desert. Earth and Planetary Science Letters, 469:15-26.[5] Roperch P., et al., 2022. Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile: COMMENT. Geology, 50.5:e550.[6] Schultz P.H., et al., 2022. Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile. Geology, 50.2:205-209.[7] Schultz P.H., et al., 2022. Widespread glasses generated by cometary fireballs during the late Pleistocene in the Atacama Desert, Chile: REPLY. Geology, 50:e551.[8] Timms N.E., et al., 2017. A pressure-temperature phase diagram for zircon at extreme conditions. Earth-Science Reviews, 165:185-202.

In our solar system, terrestrial planets and meteoritical matter exhibit various bulk compositions. To understand this variety of compositions, formation mechanisms of meteorites are usually investigated via a thermodynamic approach that neglect the processes of transport throughout the protosolar nebula. Here, we investigate the role played by rocklines (condensation/sublimation lines of refractory materials) in the innermost regions of the protosolar nebula to compute the composition of particles migrating inward the disk as a function of time. To do so, we utilize a one-dimensional accretion disk model with a prescription for dust and vapor transport, sublimation and recondensation of refractory materials (ferrosilite, enstatite, fayalite, forsterite, iron sulfur, kamacite and nickel). We find that the diversity of the bulk composition of cosmic spherules can be explained by their formation close to rocklines, suggesting that solid matter is concentrated in the vicinity of these sublimation/condensation fronts. Although our model relies a lot on the number of considered species and the availability of thermodynamic data governing state change, it suggests that rocklines played a major role in the formation of small and large bodies in the innermost regions of the protosolar nebula. The results of our model are consistent with the composition of chondrules and cosmic spherules. Our model gives insights on the mechanisms that might have contributed to the formation of Mercury's large core.

In our solar system, terrestrial planets and meteoritical matter exhibit various bulk compositions. To understand this variety of compositions, formation mechanisms of meteorites are usually investigated via a thermodynamic approach that neglects the processes of transport throughout the protosolar nebula. Here, we investigate the role played by rocklines (condensation/sublimation lines of refractory materials) in the innermost regions of the protosolar nebula (PSN) to compute the composition of particles migrating inward as a function of time. To do so, we utilize a one-dimensional accretion disk model with a prescription for dust and vapor transport, sublimation, and recondensation of refractory materials [1]. Figure 1 shows the computed composition of the PSN in the Mg-Fe-Si ternary diagram, and Figure 2 shows the same profiles but where we represent the Fe wt% as a function of heliocentric distance. We find that the diversity of the bulk composition of cosmic spherules, chondrules, and chondrites can be explained by their formation close to rocklines. This suggests that solid matter is concentrated in the vicinity of these sublimation/condensation fronts. Although our model only focuses on the most abundant refractory species (ferrosilite, enstatite, fayalite, forsterite, iron sulfide, kamacite, nickel) and relevant thermodynamic data, it suggests that rocklines played a major role in the formation of small and large bodies in the innermost regions of the protosolar nebula. The increase in iron abundance close to iron alloys rocklines gives some hints on the origin of dust particles that formed Mercury’s large core.

In this study, the insertion of fluorine into LiFePO4 was carried out under molecular fluorine F-2 at different temperatures. The reactivity strongly depends on the applied fluorination temperature, leading to very different products: core delithiation of the material is observed at low temperatures with the formation of a LiF shell around particles, while the material decomposes to gradually form a mixture of alpha-FeF3 and alpha-Li3FeF6 iron fluorides at higher temperatures. A second thermal treatment under N-2 leads to the formation of LiFePO4F in a new way that has not been reported before. Supported by X-ray diffraction, Raman, infrared, M & ouml;ssbauer spectroscopies, Li-7 nuclear magnetic resonance and electrochemical characterization of the different materials, this report demonstrates various fluorination mechanisms for LiFePO4, from chemical delithiation to the stable pure fluorinated form LiFePO4F and illustrates an innovative method that can be extended to obtain the triphylite form of NaFePO4.

A new type of silica-rich glass has been discovered associated with the known impact glass strewn field of the Atacama Desert. Based on petrography, chemical composition and indistinguishable Ar-40/Ar-39 formation ages at circa 6.6 Ma, we infer that these two glasses were produced by the same impact event, which gave rise to two successive compositionally different melt batches in close succession. The first one is a silicarich melt derived from a mixture of quartz sand and weathered magmatic rocks. It is reduced and devoid of extraterrestrial contamination. The second one, much more abundant and which corresponds to the normal glass, is oxidised, highly contaminated by the iron type impactor and derived from an underlying unweathered dacitic rock. This scheme sheds a new light on the first second of the interaction between the Earth surface and a large metallic asteroid.

We studied Caleta el Cobre 022, a nakhlite showing a high abundance of aqueous alteration products, commonly called "iddingsite" and compared it to eight other nakhlites, in order to constrain the composition and the history of the aqueous alteration of nakhlites. Olivine grains in nakhlites display planes of secondary fluid inclusions, composed of pyroxene, magnetite, and a void potentially filled by a fluid. They were formed by a first fluid alteration event, previous to the iddingsite alteration event, probably from a late magmatic fluid circulation. We observed magnetite-pyroxene symplectites in olivine grains in most nakhlites, related to the same fluid-assisted tardi-magmatic event as the crystallization of the secondary inclusion planes. Those secondary inclusions and symplectites can be observed at the center of iddingsite veins, inside the most altered nakhlites, and are thus interpreted as being weakness planes, easing the circulation of the fluid forming the iddingsite inside the olivine grains. In every nakhlite, the alteration veins show at least two types of iddingsite: a coarse iddingsite with crystals around 50 nm, up to 200 nm, and a fine iddingsite with a nanocrystalline to amorphous texture with crystalline domains <10 nm. Both iddingsite types are composed mainly of Si, Mg, and Fe, with anticorrelated Si and Fe contents. The coarse iddingsite is composed of a mixture of phyllosilicates, with Fe-oxyhydroxides and minor siderite, and the fine iddingsite has a composition close to saponite. Organic matter located in coarse iddingsite is detected by Raman spectroscopy in the iddingsite of many nakhlites and was confirmed by the TEM study of NWA 10153. In addition, the TEM study of NWA 10153 displays complex chemical zoning in the fine iddingsite of Mg, Ca, Mn, S, P, and Al, suggesting at least two stages of circulations. Both the compositions and textures of the two types of iddingsite are suggestive of a progressive evolution of the alteration fluid, enriched in elements from basaltic mineral dissolution, with crystallization mainly by filling of existing fractures, and selective dissolution of host olivine. We also observe pyrrhotite-magnetite veinlets at the center of iddingsite veins and cross-cutting iddingsite veins and silicates, which are interpreted as the result of another later fluid circulation.

In this work, we investigate macroscopic characteristics, magnetic susceptibility, mineralogy, and mineral composition of Al Haggounia 001. The samples were collected during eight field missions in the period between 2015 and 2019. In the strewn field of about 65 km in length, the specimens are found either on the surface or shallowly buried in loose sediments, which rules out the previous suggestions that this meteorite is a fossil meteorite. Macroscopically, the samples exhibit three major lithologies with various colors, porosities, and distributions of oxidized veins. The data obtained using transmitted and reflected light microscopy, scanning electron microscopy, and electron microprobe analysis confirm the macroscopic observations and show a heterogenous distribution of silicates and metal sulfides. Al Haggounia 001 is composed of enstatite, plagioclase, kamacite, taenite, schreibersite, daubreelite, troilite, graphite, sinoite, and silica polymorphs. We identified a new type of chondrules that are flattened and composed of rods of albite and enstatite, as well as elongated nodules of metal and sulfides, in addition to compression fractures in the form of subparallel veinlets. These features presumably reflect the deformation caused by shock. The magnetic susceptibility of Al Haggounia 001 (4.39 +/- 0.20) is much lower than that of usual EH (5.48 +/- 0.16) and EL (5.46 +/- 0.04) chondrites but is in the range of E finds (5.05 +/- 0.43). The thermomagnetic and hysteresis measurements are controlled by type, size, distribution of metal-sulfide nodules, arrangement of oxyhydroxide veins, and weathering. Al Haggounia 001 is an anomalous meteorite with a polymict nature. It records multiple events revealing its unique origin which expends the groups of enstatite chondrites and provides insights into the complex formation and evolution history of their parent body.

We propose a probabilistic approach to gauge the plausibility of a genetic link between a distal ejecta and a known impact structure, considering the only possible alternative that the distal ejecta could originate from an unknown impact site.We exemplify this approach in the case of three tektite strewn fields related to three known impact structures-the belizites, related to Pantasma (Nicaragua), the ivorites, related to Bosumtwi (Ghana), the moldavites, related to Ries (Germany), as well as on Manson crater ejecta.The computed probability for the unknown meteoritic impact is about 1% or less for these four cases studies.