Abstract Carbonaceous chondrites contain phosphorus, whose speciation and thus history remain to be investigated. Phosphorus/sulfur‐bearing assemblages have been reported in carbonaceous CM chondrites, but there is no consensus about their exact compositions and origins. Here, we present submicrometer‐scale investigations by analytical transmission electron microscopy of phosphorus/sulfur‐bearing assemblages from the CM chondrites Murray and Murchison. Results indicate that, in CM chondrites, phosphorus associated with sulfides occurs under distinct oxidation states. In Murray, we identified a pyrrhotite–schreibersite nanocrystalline assemblage associated with carlsbergite and chromite. Its reduced nature and petrographic context are indicative of a nebular formation mechanism, possibly through kamacite sulfidation. In contrast, Murchison contains nanocrystalline pentlandite assemblages associated with carlsbergite and likely with phosphate phases that we interpret as being produced via interactions with an oxidizing fluid under asteroidal conditions. Thermodynamic modeling suggests that such complex assemblages hosting reactive forms of both phosphorus and nitrogen could promote the synthesis of activated phosphate species such as diamidophosphate, an efficient phosphorylation reagent, thereby underscoring their potential prebiotic significance.

This study investigates the dissolution kinetics of synthetic basaltic glass under circum-neutral to basic conditions (pH20 degrees C from 6 to 10) and temperatures of 30, 60 and 90 degrees C, with a particular focus on the roles of dissolved oxygen (O2(aq)) and silica (SiO2(aq)) concentrations. Surface retreats were measured using vertical scanning interferometry, and the thickness of alteration layers (amorphous silica-rich surface layer, referred to as ASSL) using X-ray reflectivity and transmission electron microscopy performed on focused ion beam-milled lamellae. As expected, the dissolution rate of basaltic glass increases with increasing pH from neutral to basic conditions. A modest influence of O2(aq) concentrations was observed, attributed to Fe(II) oxidation and the associated formation of a passivating Fe(III)-Si-rich surface layer. Most strikingly, the dissolution rate was found to decrease exponentially with increasing SiO2(aq) concentrations, which is inconsistent with the transition state theory. Instead, this behavior is consistent with a mechanism governed by classical nucleation theory in the studied conditions, resulting in the following overall dissolution rate law: r = () k0.10n.pHT.exp Ea.exp k1 k2, with r being the dissolution rate (in mol/m2/s), k0 = 552 mol/ RT |ln[SiO2(aq) ]/KTeq | m2/s, n = 0.35, Ea = 84 kJ/mol, k1 = 0.40, k2 = 3.87, pHT is the pH value at the considered temperature T, R the gas constant, and KTeq the solubility constant of amorphous silica at the considered temperature. Taken together, these findings provide new insights into the coupled effects of pH, O2(aq), and SiO2(aq) on basaltic glass reactivity, offering a refined kinetic framework for modeling glass weathering in natural and engineered environments.

The aim of this study was to investigate the contribution of Fe(III)-reducing microorganisms to the dissolution rates of Fe(III)-rich synthetic basaltic glass. Hyperthermophilic archaeon Pyrobaculum islandicum and thermophilic bacterium Thermus scotoductus were incubated for 7 or 15 days with basaltic glass, and the surface retreat of the glass was determined using vertical scanning interferometry. Pyrobaculum islandicum was shown to enhance basaltic glass dissolution rate two-fold compared to abiotic controls in 7-days incubations. However, this effect was only 1.3-fold in 15-days incubations. In contrast, Thermus scotoductus did not impact or slightly inhibited the dissolution. Accordingly, alteration microstructures of the surface were visible only with Pyrobaculum islandicum cultures which promoted the formation of (Al, P, S)-rich layers thickening with time at the surface of the glass as well as of (Fe, S)-bearing crystals. To identify the underlying mechanisms that could explain such differences, Fe(III) reduction assays were performed in cultures with Fe(III) citrate, revealing higher rates of Fe(III) reduction in incubations with Pyrobaculum islandicum compared to those with Thermus scotoductus. Collectively, these findings suggest that Fe(III)-reducing microorganisms can enhance basaltic glass dissolution, but that the process could be limited by the rate of Fe(III) reduction and by surface alteration products.

Extremophiles, microorganisms that thrive in extreme environments, have broadened our understanding of fundamental life processes. Cultivated strains of extremophiles have demonstrated the viability of life at temperatures up to 122 degrees C and pressures up to 125 MPa. These physical extremes affect intracellular mechanisms such as metabolism. At high temperatures, the key metabolite adenosine triphosphate (ATP) is subject to abiotic hydrolysis. In cells, ATP is complexed mostly with Mg2+. Although this complexation is well known, its role during abiotic ATP hydrolysis under extreme conditions has rarely been investigated. This study presents novel kinetic data which are supported by thermodynamic modeling pertaining to ATP hydrolysis at elevated temperatures and 20 MPa in presence of Mg2+ and other cations. Kinetic parameters for abiotic hydrolysis were determined using in situ Raman spectroscopy in combination with a hydrothermal diamond anvil cell and a gas-pressurized autoclave equipped with a sapphire cell. Hydrolysis rate constants were studied using Mg2+, Ca2+, and Na+ as ATP counterions at temperatures of 80 degrees C, 100 degrees C, and 120 degrees C under pressures of 20 MPa. Our findings indicate that Na+ and Ca2+ ions have negligible effects on ATP hydrolysis rates. In contrast, increasing the Mg2+ concentration to fourfold the ATP concentration resulted in a pronounced decrease of the hydrolysis rate, with reductions of approximately 30 % at 80 degrees C and 50 % at 120 degrees C. By comparison with known biotic pool turnover rates, this kinetic stabilization of ATP reinforces previous findings that its abiotic hydrolysis is not a limiting factor for life at high temperature. Furthermore, these results suggest that Mg2+-rich intracellular compositions can reduce the energy investment required to maintain ATP homeostasis in biological systems. Thermodynamic modeling revealed increasing complexation of ATP with Mg2+ ions with increasing temperature and magnesium ions concentration. Under experimental conditions of pH 2 to 3, a continuous formation of MgH2ATP complexes was calculated, leading to a deceleration of the abiotic hydrolysis rate. At pH 6 to 9, the formation of MgATP2-was calculated at equimolar concentrations of ATP and Mg2+ ions. Above 80 degrees C and pH values between 6 and 9, thermodynamic modelling indicated the formation of Mg2ATP when the Mg2+ concentration was increased above the equimolar point.

In cells, many small molecules are membrane-permeant. This feature opens a road to analyze their flux of production or consumption by quantitatively interpreting the map of their extracellular concentration within a reaction-diffusion frame. Here, this approach is implemented with a new wide-field lifetime imaging protocol applied to single microalgae cells sparsely deposited on an agarose pad loaded with a luminescent dioxygen (O2) nanosensor. The resulting maps are processed to access the spatial distribution of the O2 concentration in the plane of the cells. After fitting the data, the cellular O2 flux is extracted, evidencing a span of magnitudes and angular dependencies in the balance between photosynthesis and respiration. Beyond pointing to the disparity of individual behavior within the same colony, this work validates a simple approach for characterizing metabolic fluxes of membrane-permeant molecules down to the single-cell level.

Geological structures known as alkaline hydrothermal vents (AHVs) likely displayed dynamic energy characteristics analogous to cellular chemiosmosis and contained iron-oxyhydroxide green rusts in the early Earth. Under specific conditions, those minerals could have acted as non-enzymatic catalysts in the development of early bioenergetic chemiosmotic energy systems while being integrated into the membrane of AHV-produced organic vesicles. Here, we show that the simultaneous addition of two probable AHV components, namely nickel and amino acids, impacts green rust’s physico-chemical properties, especially those required for its incorporation in lipid vesicle’s membranes, such as decreasing the mineral size to the nanometer scale and increasing its hydrophobicity. These results suggest that such hydrophobic nano green rusts could fit into lipid vesicle membranes and could have functioned as a primitive, inorganic precursor to modern chemiosmotic metalloenzymes, facilitating both electron and proton transport in early life-like systems.

Carbonate minerals are important in Earth's system sciences and have been found on Mars and in meteorites and asteroids, highlighting the importance of impacts in planetary processes. While extensively studied under static compression, the behavior of carbonates under shock compression remains underexplored, with no in situ X-ray investigations reported so far. Here we investigate natural magnesiosiderite (Fe_0.6Mg_0.4CO_3) under nanosecond laser-driven shock compression at pressures up to 150 GPa, coupled with in situ ultrafast synchrotron X-ray absorption spectroscopy (XAS). The interpretation of the experimental spectra is complemented using first-principles absorption cross-section calculations performed on crystalline phases at different pressures and on a dense liquid phase obtained using density functional theory-based molecular dynamics (DFT-MD) simulations. Under laser-driven shock compression, the magnesiosiderite crystal phase remains unchanged up to the melt. Under shock reverberation, the absorption spectra show changes similar to those attributed to a high-spin to low-spin transition observed under static compression. At higher pressures, the laser shock induces the formation of CO_4 tetrahedral units in the melt. Upon unloading from the shocked state, only a few nanoseconds later, the original magnesiosiderite phase is recovered.

We present measurements on Fe2O3 amorphization and melt under laser-driven shock compression up to 209(10) GPa via time-resolved x-ray diffraction. At 122(3) GPa, a diffuse signal is observed indicating the presence of a noncrystalline phase. Structure factors have been extracted up to 182(6) GPa showing the presence of two well-defined peaks. A rapid change in the intensity ratio of the two peaks is identified between 145(12) and 151(12) GPa, indicative of a phase change. The noncrystalline diffuse scattering is consistent with shock amorphization of Fe2O3 between 122(3) and 145(12) GPa, followed by an amorphous-to-liquid transition above 151(12) GPa. Upon release, a noncrystalline phase is observed alongside crystalline α−Fe2O3. The extracted structure factor and pair distribution function of this release phase resemble those reported for Fe2O3 melt at ambient pressure. Published by the American Physical Society 2025

Phosphorus is an essential building block of life, likely since its beginning. Despite this importance for prebiotic chemistry, phosphorus was scarce in Earth's rock record and mainly bound in poorly soluble minerals, with the calcium-phosphate mineral apatite as key example. While specific chemical boundary conditions have been considered to address this so-called phosphate problem, a fundamental process that solubilizes and enriches phosphate from geological sources remains elusive. Here, we show that ubiquitous heat flows through rock cracks can liberate phosphate from apatite by the selective removal of calcium. Phosphate's strong thermophoresis not only achieves its 100-fold up-concentration in aqueous solution, but boosts its solubility by two orders of magnitude. We show that the heat-flow-solubilized phosphate can feed the synthesis of trimetaphosphate, increasing the conversion 260-fold compared to thermal equilibrium. Heat flows thus enhance solubility to unlock apatites as phosphate source for prebiotic chemistry, providing a key to early life's phosphate problem.

Manufactured infrastructures of urban areas, including buildings and roads, are contributors of solid particles to the environment due to wear processes and further weathering. Mineral dusts produced by such mechanisms are transported by air or water across urban compartments until they accumulate in surrounding natural and artificial sediment reservoirs, mixing with other minerals of geogenic sedimentary origin. With the expansion of artificialized urban surfaces over time, the contribution of urban-sourced minerals is expected to increase in sediment fluxes, thus taking an increasing importance in biogeochemical cycles. In this study, we postulate that mineral particles emitted from specific man-made materials could be traced in different compartments of urban environments on the basis of their mineralogical signature. Such identified urban mineralogical components could then serve as useful markers to monitor urbanization wear processes and subsequent emprise of urbanization at the regional scale. Here, we have analyzed a collection of urban samples, which comprises urban dusts, road sediment deposits, suspended particulate matter from the Seine and Orge rivers near Paris, and sediments accumulating in stormwater basins along high traffic roads in the Paris region (N118, N104). In almost all of the solid samples studied (n = 34), whose sampling span over a ten-year period, we show by powder X-ray diffraction (XRD) the presence of minerals belonging to the amphibole group, which are necessarily derived from human activities since these minerals do not belong to the Parisian sedimentary basin. Detailed analysis of a mineral pellet embedded in bitumen of road treads sampled in a Paris street by analytical electron microscopies and Rietveld refinement analysis of powder XRD pattern show that a ferro-magnesio-actinolite is a major constituent (17 wt%) of this road material. Further analysis of an amphibole grain in a road dust sample by single crystal X-ray diffraction also points to such FeMg-actinolite of Ca2.15Mg2.44Fe2.56Si8O22(OH)2 composition. Other samples collected in the vicinity of areas subjected to road water runoff also contain amphibole minerals of close crystal-chemical composition to this FeMg-actinolite, likely designating road aggregates as sources of amphiboles in our broad set of samples. A large distribution of sizes was observed for amphibole particles using electron microscopy, from massive (100-10 mu m) to micrometric packages of elongated mineral particles, likely produced by cleavage of massive particles. The presence of micrometric minerals with elongated fiber habit raises questions about public exposure to such urban dusts. This amphibole signature is also detected in samples of river suspended particulate matter from strongly artificialized urban areas, including in a punctual sample collected in the Seine River, which emphasizes the pervasive occurrence of such minerals in this urban environment. Additionally, the presence of amphibole is suggested by X-ray diffraction on a sample taken on a building roof, which calls for a quantitative investigation of amphibole transport pathways, including air transport, in urban areas. Finally, we propose that this amphibole mineralogical pattern could be used as a mineralogical tracer of city wear and urbanization influence on sedimentary fluxes produced by urban materials.

The iron speciation and valence state of meteorites reflect the formation conditions and evolution of primitive bodies in the solar system. This idea is illustrated in an iconic plot in planetary science, the so-called Urey-Craig (UC) diagram, where the amount of iron accommodated in sulfides and metallic alloys is plotted versus that found in oxides and silicates. Hydrous carbonaceous chondrites (i.e., CI and CM type) are usually considered as the oxidized end-member. Here, we reevaluate the position of CIs in the UC diagram based on available data from recent space missions that sampled CI-like materials and by a recently found CI meteorite (Oued Chebeika 002) using X-ray diffraction and Mossbauer spectroscopy. Moreover, we report new data for C2-ungrouped (e.g., Tagish Lake and Tarda), CM, and CR chondrites containing varying proportions of clay minerals. The results show that the recently fallen CI and C2-ungrouped samples contain a considerable amount of iron sulfides, and metallic iron was identified in less altered CM samples, indicating that they are not completely oxidized. The updated UC diagram shows that the formation environments of CI materials are much more reduced than previously assumed, possibly implying that the oxygen fugacity that prevailed during CI material formation might not be far from that of some non-carbonaceous chondrites (e.g., L and LL type). Furthermore, the metal-bearing CM samples have Fe3+-rich poorly-crystalline phases, and the Fe3+/(Fe3++Fe2+) ratio in clay minerals decreases with increasing alteration intensity. The CI and C2-ungrouped samples do not follow this CM trend, suggesting distinct redox-controlling processes.

Iron oxide nanoparticles have been proposed for magnetic hyperthermia treatment of tumors. However, efficacy depends on the injection of large amounts of such nanoparticles and the equipment is costly. Here, a new thermal cancer treatment is described, in which a tumor containing a low concentration of nonpyrogenic pure iron oxide nanominerals coated with carboxy-methyl-dextran (M-CMD), corresponding to modified magnetosomes, are exposed to ultrasound. Heating PC3 prostate carcinoma cells between 43 and 46 degrees C using ultrasound in the presence of M-CMD resulted in significant necrotic cell death. Furthermore, deposition of M-CMD containing 3 mu g of iron per mm3 of tumor in subcutaneous xenografts of PC3-Luc tumors of 150 mm3 followed by 6 to 10 sessions of ultrasound application (1 W cm-2, 1 MHz) of 10 min each led to a tumor temperature of 43-46 degrees C per session and to total tumor disappearance without regrowth over 6 months following treatment start. Sequential histological analyses of the tumor tissues revealed partial tumor occupation by M-CMD and an increase in cell death over time. Neither lesions, nor magnetosome accumulation were found in microscopic sections of various internal organs collected from treated mice euthanized 6 months after the beginning of the treatment, indicating that M-CMD may not lead to long-term side effects.

Magnetotactic bacteria (MTB) possess the ability to precipitate intracellular nanosized magnetite. Their emergence may date back to the early Archean (e.g. 3 Ga) but evidence of such a long history has yet to be provided. MTB identification in the rock record relies on magnetofossils, the residual magnetite crystals that may survive in time to rock deformation and low-grade metamorphism. Several criteria such as size, shape and magnetic properties have been proposed to distinguish magnetofossils from other magnetite sources. Recent experimental work on the freshwater strain Magnetospirillum magneticum AMB-1 revealed that Fe isotope composition represents a promising additional criterion, but isotopic characterization of distinct MTB strains and of their magnetite needs to be provided to evaluate the robustness of iron isotope signatures for paleontological applications. In the present work, we investigate the marine strain Magnetovibrio blakemorei MV-1 under various conditions selected to examine the influence of Fe concentration (50, 100 and 150 mu M) and redox state (Fe(II)-ascorbate or Fe(III)citrate) on bacterial biomineralization and determine associated Fe isotope fractionations. Our results confirm the preferential incorporation of light iron isotopes into magnetite relative to the bacterial growth medium previously observed in AMB-1. Modeling the evolution of the growth medium and magnetite isotope compositions by Rayleigh distillation process yields iron isotope fractionations (i.e. Delta 56Fegrowth medium-magnetite = delta 56Fegrowth medium-delta 56Femagnetite) ranging between 0.2 and 0.9 %o with a mean value of 0.55 (+/- 0.35) %o. This isotope fractionation shows no clear relation with iron concentration or redox state. Importantly, the enrichment in light iron isotope of biological magnetite contrasts with the isotopic characteristics of magnetite formed by abiotic precipitation, the latter being enriched in heavy isotopes. This suggests that Fe isotopes could be used as a biosignature for magnetofossils identification in terrestrial or extraterrestrial samples. Finally, in contrast with previous results obtained on AMB-1, no specific enrichment of 57Fe (relative to 54Fe, 56Fe and 58Fe) could be detected in MV-1 magnetite, which we interpret by differences in iron budgets between the two strains.

Alkaline hydrothermal vents are plausible environments for the emergence of life on Earth. By means of a simplified analogical reconstruction of the vent-ocean interface of these systems reproducing early Earth conditions, we show that iron (oxy-hydr)oxide minerals may have carried out proto-bioenergetic processes driven by pH and redox gradients. The initial pH gradient precipitates the iron (oxy-hydr)oxide mineral barriers (magnetite, green rust and amakinite) and yields reducing conditions, enabling the production of metallic iron at room temperature via the disproportionation of Fe2+ to Fe3+ and Fe0. The crystallographic association of Fe0 surrounded by magnetite suggests the coupling of Fe3+ / H2 co-production at ambient temperature by amakinite oxidation with the thermodynamically unfavorable reduction of Fe2+ to Fe0. This abiotic disproportionation process coupling exergonic and endergonic reactions may serve as a proto-bioenergetic mechanism increasing the non-equilibrium reduction state of the system and offers an interesting analog of the biological electronic bifurcation reaction, the free energy coupling being a fundamental thermodynamic trait of life-as-we-know-it.

The origin and formation mechanisms of phosphate minerals in L and LL ordinary chondrites remain an open question. Here we report detailed quantitative data on the abundances, grain sizes and compositions of apatite and merrillite in L, LL and L/LL chondrites, covering a total analysed area of -2730 mm2. Our results show that the abundances of phosphate minerals are slightly higher in L than in LL chondrites and reveal distinct petrographic differences between merrillite and apatite. Merrillite abundance is anti-correlated with Fe, Ni metal content and increases with petrologic type, as does grain size - indicating grain coarsening processes - supporting the formation of this mineral during thermal metamorphism. In contrast, apatite shows no clear trend in abundance or grain size with petrologic type. Although chlorine contents are similar between apatites from L and LL chondrites, the small dispersion of Cl concentration and its decrease with petrologic type in LL chondrites indicate that apatites in these chondrites undergo equilibration with increasing thermal metamorphism, a pattern not observed in L chondrites. Although the Cl contents in apatites are fairly homogeneous across the samples, scarce F-rich apatites have been observed in some meteorites, leading to significant variability in Cl#. However, due to low concentrations and analytical challenges, we argue that comparisons between different OC groups should primarily be based on Cl concentrations. Furthermore, apatite and merrillite have different grain size distributions in L chondrites, but similar ones in LL chondrites, where they also occur as close assemblages, suggesting a petrogenetic relationship between apatite and merrillite in LL chondrites, but not in L chondrites. Overall, the present study suggests that phosphates did not have exactly the same history in L and LL chondrites.

Abstract Iron sulfide (Fe-S) minerals such as mackinawite (FeS), greigite (Fe3S4) and pyrite (FeS2) are widespread on Earth, where their formation and dissolution are strongly linked to the biogeochemical cycles of iron, sulfur, carbon, oxygen, nutrients and trace metals. Recent studies have shed light on how microorganisms mediate their formation, with breakthroughs linked to biogenic pyrite. In this review, we highlight the formation pathways of Fe-S minerals, starting with the increasingly recognized roles of Fe(III) and intermediate sulfur species (e.g. S0 and polysulfides) during the initial steps. The mechanisms by which microorganisms affect Fe-S mineral formation are compiled and discussed for low (25–35°C) and high (≥ 80°C) temperatures, with specific examples from experimental studies. The morphology and precipitation rates obtained from experiments are compared to natural environments, and their similarities and differences are critically discussed. We then review the current state of the art for Fe-S minerals in the context of the origin of life and as environmental proxies and biosignatures in the geological record using their texture and chemical and isotopic compositions. We end by highlighting the importance of Fe-S minerals for current societal issues, such as the sequestration of organic carbon, the formation of acid drainages, metal recovery and nitrate removal, and their potential use as technological bio-materials in the future.