Ildikó Gyollai

This study reveals the effects of artificial space-like proton irradiation on three meteorite samples that are Northwest Africa (NWA) 4560 LL3.2 and NWA 5838 H6 chondrite meteorites, as well as the Dhofar (Dho) 007 eucrite. We used low-vacuum scanning electron microscopy (LV-SEM) and Raman Spectroscopy to examine the structure and composition of olivine and pyroxene grains in the meteorites before and after the irradiation events. This article focuses on the strongest and most intense irradiation, which was performed by protons up to 12 keV with a fluence value of 10¹⁹ ions/cm² that lasted ~30 h. According to the Raman spectra, significant lattice disruption in all analyzed silicates occurred, and a more extensive amorphous, glassy layer developed under the strongest irradiation conditions. Relative to the second irradiation, peak 1 (820.0 cm⁻¹) shifts slightly negatively (–0.46 cm⁻¹) with a small FWHM increase (+0.88 cm⁻¹), while peak 2 (850.3 cm⁻¹) shifts positively in both parameters (+0.40 and +4.04 cm⁻¹) in NWA 4560 olivines. In NWA 5838 olivines, both olivine peaks (820.5 and 850.8 cm⁻¹) shift positively (+7.40 and +7.90 cm⁻¹) and broaden (+2.75 and +4.29 cm⁻¹). In Dho 007 pyroxenes, peak 1 (997.1 cm⁻¹) shifts positively (+3.01 cm⁻¹) with an FWHM decrease (−0.46 cm⁻¹), peak 2 (669.7 cm⁻¹) shifts slightly negatively (−0.75 cm⁻¹) while broadening strongly (+29.23 cm⁻¹), and peak 3 (327.7 cm⁻¹) shifts positively (+0.86 cm⁻¹) with reduced FWHM (−4.55 cm⁻¹). Three characteristic amorphous bands appear in all examined meteorite silicates, located at ~550–1000 cm⁻¹, ~1100–1700 cm⁻¹, and ~1700–1850 cm⁻¹. Olivines in NWA 4560 and NWA 5838 exhibited similar responses across all irradiation events. In contrast, Dho 007 pyroxenes showed variable compositional changes without a consistent or well-defined pattern in our SEM dataset. The Fo decrease in our experiments likely results from preferential Mg sputtering in the olivine lattice, leading to relative Fe enrichment, similar to but more pronounced than after the first irradiation. Pyroxenes exhibit a comparable response, with Fs and En increasing and Wo sharply decreasing, reflecting preferential Ca loss relative to Mg alongside Fe enrichment. Investigating these processes improves the interpretation of planetary remote sensing data and advances our understanding of planetary surface evolution, while also clarifying how surface materials respond to space environmental conditions.

Artificial space weathering tests on NWA 10580 CO3, NWA 11469 CO3, NWA 5838 H6, NWA 4560 LL3.2, and Dho 007 Eucrite meteorites using solar wind relevant proton irradiation were performed. The experiments revealed increased iron content, amorphization, water loss, and structural changes that typically reduce the mechanical hardness of the outermost surface layer. Results support both meteorite-asteroid linking and optimization of future infrared detector channel arrangement for cubesat asteroid missions.IntroductionArtificial space weathering tests in the laboratory of ATOMKI on meteorites using solar wind relevant proton irradiation were performed. The simulation corresponded to 10-100 million years of space weathering exposure, and the resulting changes were detected by infrared, Raman, SEM and XRD measurements before and after the irradiation actions. The aim was to better understand the modifications by surveying the sample with different methods and interpreting the results jointly. The findings are expected to support a better understanding of asteroid spectra, the linking of meteorites to source asteroids, and improved detector band localization for upcoming missions.Simulated solar wind can induce mineral amorphization, detectable by infrared (IR) spectroscopy (Demyk et al. 2004; Lantz et al. 2015) and Raman spectroscopy (Brucato et al. 2004; Demyk et al. 2004), through band shifts in silicates and compositional changes (Hapke et al. 1975). Nanophase iron-nickel particles have also been identified in CV and CO chondrites post-irradiation (Zhang et al. 2023). These effects are primarily analyzed using Fourier Transform Infrared (FTIR) spectroscopy on bulk samples (Lantz et al. 2017; Brunetto et al. 2014, 2020), and Raman spectroscopy (e.g., olivine: Lantz et al. 2017; polystyrene and olivine: Kanuchova et al. 2015). Beyond scientific interest, understanding the composition and mechanical properties of Near Earth Asteroids - potentially influenced by surface modification of grains within rubble pile structure objects - is essential for developing effective mitigation strategies and improving the spectral correlation with meteorites.MethodsThe meteorite samples (NWA 10580 CO3, NWA 11469 CO3, NWA 5838 H6, NWA 4560 LL3.2, and Dho 007 Eucrite) were irradiated with 1 keV H+ protons produced by the ECR ion source (Biri et al. 2021) at the ATOMKI institute under vacuum conditions, up to a fluence of 1017 ion/cm2. The samples were analyzed before and after irradiation actions using the following facilities. For sample analysis FTIR spectroscopy was performed using a Vertex 70 spectrometer with 32 scans in the 400–4000 cm−1 range, measured for 30 s at 4 cm−1 spectral resolution, processed using Bruker Optics’ Opus 5.5. software. Raman spectroscopy was applied using a Morphologi G3-ID instrument (Malvern Instruments; Garzanti et al. 2015) and a Kaiser Optical Systems Inc. Raman Rxn1 Spectrometer with NIR Laser Diode at 785 nm wavelength. Measurements were taken with an exposure time of 30 s at 10 mW laser power over the 150 - 1150 cm-1 range. The laser spot size was 3 μm at 50× magnification, with a spectral resolution of 1 cm−1 and a focal depth of 1.82 μm. The Scanning Electron Microscope (SEM) used was a JEOL JSM-IT700 HR, operated at a 20 keV voltage and 6 nA beam current, with a 40 s point integration time and 100 s areal integration time.ResultsA range of changes was observed in peak positions, FWHM values, and the disappearance of minor bands, indicating the following sequence of alterations during the series of irradiation and measurement sequences.Metastable phases may form ephemerally under conditions differing from those of stability, as shown by Lindsley et al. (1972) in their identification of metastable pyroxferroite related to smectites in cosmic materials, or in specific mineral-like alloys(Lilienfeld et al., 1987), where irradiation modified grain boundaries and dislocations (Chesser et al., 2024). However, such effects have rarely been explored in irradiated meteorites. Defect production occurred in the crystalline lattice during the next phase, where vacancy migration was likely influenced by temperature (Campbell et al., 2002, ). These defects could reduce band strength and increase FWHM in general. Element migration, replacement, and ion integration occurred, particularly affecting olivine composition, which changed from Fo-50–60 (Hamilton 2010) to Fo-30–35 after irradiation in Frontier Mountain 95,002 and Lancé meteorites (Brunetto et al., 2020), as well as in Tagish Lake sample following ion irradiation (Dukes et al., 2015). We also observed an increase in the Fe/Si ratio during the later stages of the tests at elevated irradiation fluence. Amorphization and mineral decomposition were characteristic of the later phase of the tests, occurring at higher levels of irradiation. Excessive defect formation and element loss or implantation were observed. In silicates, depolymerization of SiO4 tetrahedra and lattice decomposition led to the weakening, and disappearance of spectral bands. We also evaluated mineral identification possibilities using different spectral resolution, as onboard cubesats simple detectors are expected to be used for asteroid missions frequently in the near future. Spectral coarsening, achieved by artificially lowering the resolution with averaging data points, leads to flattening on a smaller scale. Smaller peaks tend to disappear quickly with the worsening resolution.Discussion and ConclusionThe experiments revealed increased iron content, amorphization, water loss, and structural changes that typically reduce the mechanical hardness of the outermost surface layer, supporting the linking of meteorites to asteroids; however, one major further step remains: the inclusion of laser-shot-simulated microscopic impact effects, resulting melting, darkening and nanophase iron formation. The...

Raman and infrared measurements of the same locations were conducted on a northwest African (NWA) 10580 CO3 meteorite sample, before and after three proton irradiations (1 keV ion energy using 10¹¹, 10¹⁴, and 10¹⁷ ion/cm² fluent values), to simulate space weathering effects. In the case of Raman spectroscopy, both FWHM and peak positions of the major olivine and pyroxene bands changed after the irradiation, and the minor bands disappeared. In the FTIR spectra, the minor bands of olivine and pyroxene also disappeared; meanwhile, major IR bands of pyroxene remained visible, demonstrating both positive and negative peak shifts, and the olivines were characterised only by negative peak shifts. The olivines were characterised by negative FWHM changes for major bands, but positive FWHM changes for minor bands. The pyroxenes were characterised by elevated FWHM changes for minor bands after the irradiation. The disappearance of minor bands both of IR and Raman spectra indicates the amorphization of minerals. The negative peak shift in IR spectra indicates Mg loss for olivine and pyroxene, in agreement with the literature. The Raman spectra are characterised by positive peak shift and positive FWHM changes; the IR spectra are characterised by a negative peak shift. The Mg loss, which was detected by negative peak shifts of FTIR bands, may be caused by distortion of the crystal structure, which could be detected by a positive peak shift in Raman spectra. This joint observation and interpretation has not been formulated in the literature, but indicates further possibilities in the confirmation of mineral changes by different instruments. Shock alteration-based observations by other researchers could be used as a reference for irradiation experiments as irradiation makes a similar structural alteration, like a low-grade shock metamorphism.

Continental rifting of the Tisza microplate started during the Late Jurassic and resulted in phreatic eruptions, peperite, and the construction of a volcanic edifice in the Early Cretaceous in the Mecsek Mountains (South Hungary). In the SE direction from the volcanic edifice at Zengővárkony, a shallow marine (depth 100–200 m) carbonate sediment hosted a vent environment, and iron ore deposition occurred at the end of the Valanginian to early Hauterivian, hosting a diverse, endemic fauna of approximately 60 species. The detailed mineralogical analysis of the transport conduits included Fe oxides (ferrihydrite, goethite, hematite, and magnetite), quartz, mixed carbonate, pyrite, feldspar, Fe-bearing clay minerals, apatite, sulfates (barite, gypsum, and jarosite), and native sulfur. Filamentous, microbially mediated microtextures with inner sequented, necklace-like spheric forms (diameter of 1 μm) and bacterial laminae are also observed inside decapod crustacean coprolites (Palaxius tetraochetarius) and in the rock matrix. This complex ecological and mineralogical analysis provided direct evidence for the presence of bacteria in fossil sediment-hosted vent (SHV) environments on the one hand and for the intimate connection between bacteria and decapod crustaceans in hydrothermal environments 135 Ma before. This observation completes the fossil food chain of chemosynthesis-based ecosystems, from primary producers to the top carnivores reported for the first time from this locality.

Continental rifting of the Tisza microplate has started during the Late Jurassic that resulted phreatic eruptions, peperites, and built up a volcanic edifice in the Early Cretaceous of the Mecsek Mountains (South Hungary). In SE direction from the volcanic edifice at Zengővárkony a shallow marine (depth 100 – 200 m) carbonate sediment hosted vent environment and iron-ore deposition occurred at end Valanginian too early Hauterivian hosting a diverse, endemic fauna of around 60 species. Detailed mineralogical analysis of the transport channels include Fe oxides (ferrihydrite, goethite, hematite, magnetite), quartz, mixed carbonate, pyrite, feldspar, Fe-bearing clay minerals, apatite, sulphates (barite, gypsum, jarosite) and native sulphur. Filamentous, microbially mediated microtexture with inner sequented, necklace-like spheric forms (diameter 1 μm) and bacterial laminae are observed inside the decapod crustacean coprolites (Palaxius tetraochetarius) and in the rock matrix, too. This complex, ecological and mineralogical analysis provided direct evidence for the presence of bacteria at fossil SHV environments on one hand, and the intimate connection between bacteria and decapod crustaceans at hydrothermal environments 135 Ma before. This observation completes this chemosymbiotic fossil food chain from the primary producers to the top carnivores reported for the first time from this locality.

We studied the occurrence of secondary minerals and inferred their formation in the Yamato‐000593 Martian meteorite using multiple technological approaches such as electron probe micro analysis, optical microscope, Raman spectroscopy, scanning electron microscopy, as well as Fourier transform‐infrared microscopy and spectroscopy. Two separate hydrothermal alteration events and their sequence of formation (based on superpositional relationship) can be identified: an elevated temperature phase producing high‐temperature sulfidic hydrothermal alteration and a lower temperature hydrothermal alteration phase by iron‐rich fluids. This meteorite shows signatures more compatible with magmatic effects, rather than impact‐induced hydrothermal alteration, as has been proposed earlier. The sulfidic alteration probably formed by magmatic hydrothermal fluids, whereas iron‐rich hydrothermal fluid circulation after a possible early impact event has also been proposed, when the fluids cooled down to 50 °C. Most of the secondary minerals formed at alkaline‐neutral conditions, and the few observed signatures (clay–silica‐bearing veins, siderite‐iron‐oxide veins) of briny conditions are probably from local spatial effects in larger cavities. The ferrous minerals (hematite and siderite) along the fractures could be crystallized from Fe‐HCO₃‐bearing fluids. Alternatively, the primary magmatic minerals could have been oxidized easily (Fe‐rich olivines, magnetite) during the cooling to iron oxides (hematite, goethite). The results suggest the possible existence of at least ephemerally habitable environments on Mars, mainly at volcanically heated locations. Following published geochemical models, the carbonates formed within acidic‐circumneutral condition, which was followed by formation of phyllosilicates in alkaline condition.

The role of biogenicity in the mineral world is larger than many might assume. Biological processes and physical and chemical processes interact both at the Earth’s surface and far underground, leading to the formation of banded iron and manganese deposits, among others. Microbial mats can form giant sedimentary ore deposits, which include enrichment of further elements. This article reviews the ways in which microbially-mediated processes contribute to mineralization, the importance of mineralized microbial textural features, and the methods that must be used to obtain high-resolution datasets. If the chosen methodology and/or the size dimension of investigation is not appropriate, then it is not possible to recognize that a system is microbially mediated, and the conclusion will be incomplete. We call attention to variable authigenic mineralization as the result of complex mineralization of cells and extracellular polymeric substances in the starving basins, which form giant ore deposits together with ore-forming minerals. Microbial mats and other biosignatures can serve as indicators of environmental reconstruction in ore formations. We suggest tests and analyses that will allow the potential role of biomineralization to be properly investigated for a more comprehensive view of formation processes and their implications.