Jens Najorka

The Carri Laufquen Lakes System is a highly alkaline, basalt‐hosted lacustrine environment in northern Patagonia, Argentina. Diverse morphologies of Late Pleistocene sub‐fossil stromatolites occur along the lakeshores. Using detailed optical and electron microscopy, spectroscopy and organic geochemical analyses, this study shows that stromatolite growth and early diagenetic processes were strongly influenced by microbially controlled organomineralisation. Mineralisation of extracellular polymeric substances and cyanobacterial sheaths promoted early lithification and exceptional preservation of stromatolite fabrics and biosignatures. Organic matter is closely associated with Al–bearing silicate minerals at the micro–nanoscale, enhancing fossilisation potential and preserving biogeochemical signatures. The resulting mineral assemblage in the Carri Laufquen stromatolites, dominated by Mg‐carbonate with minor Al‐silicates and carbonaceous material, resembles the geochemistry of ancient lacustrine deposits around the margins of Jezero crater, highlighting the propensity of such deposits for biosignature preservation, and providing a framework for detailed characterisation of such materials following Mars Sample Return.

Silk is an extraordinary natural material whose unique chemistry and hierarchical organization enable performance beyond that of many synthetic counterparts. However, its poor processability arising from the molecular folding patterns of fibroin makes fabricating shapes other than fibres conceptually challenging. Here we report a simple and rapid thermomechanical process to fuse silk fibres into solid materials of arbitrary shapes. This approach avoids silk dissolution and subsequent regeneration – processes typically associated with a substantial environmental footprint due to extensive solvent use. The resulting fused silk exhibits remarkable mechanical properties (flexural strength up to 510 MPa, tensile toughness up to 45 MJ m ⁻³ ), optical transparency in the visible range, pronounced optical activity in the terahertz range with large polarization rotation and processing-dependent biocompatibility and biodegradability. The molecular organization of fused silk emerges from interdiffusion of the naturally present amorphous phase, generating strong intrafibre and interfibre molecular bonds without damaging the original hierarchical organization and the crystalline regions. This direct conversion of natural silk fibres into structural and optically active materials enhances the prospects for scalable production and real-world deployment.

Fire-making is a uniquely human innovation that stands apart from other complex behaviours such as tool production, symbolic culture and social communication. Controlled fire use provided adaptive opportunities that had profound effects on human evolution. Benefits included warmth, protection from predators, cooking and creation of illuminated spaces that became focal points for social interaction^1,2,3. Fire use developed over a million years, progressing from harvesting natural fire to maintaining and ultimately making fire⁴. However, determining when and how fire use evolved is challenging because natural and anthropogenic burning are hard to distinguish^5,6,7. Although geochemical methods have improved interpretations of heated deposits, unequivocal evidence of deliberate fire-making has remained elusive. Here we present evidence of fire-making on a 400,000-year-old buried landsurface at Barnham (UK), where heated sediments and fire-cracked flint handaxes were found alongside two fragments of iron pyrite—a mineral used in later periods to strike sparks with flint. Geological studies show that pyrite is locally rare, suggesting it was brought deliberately to the site for fire-making. The emergence of this technological capability provided important social and adaptive benefits, including the ability to cook food on demand—particularly meat—thereby enhancing digestibility and energy availability, which may have been crucial for hominin brain evolution³.

Samples of asteroid (101955) Bennu delivered by the OSIRIS-REx mission offer the opportunity to study pristine planetary materials unchanged by exposure to the terrestrial environment. Here we use a combination of X-ray diffraction and various electron microscopy techniques to explore the detailed mineralogy of Bennu samples and determine the alteration history of the planetesimal protolith from which they originated. The samples consist largely of hydrated sheet-silicate minerals, namely nanoscale serpentine and saponite of varied grain size, which are decorated with micro- to nanoscale Fe-sulfides, magnetite and carbonates. We observe sheet silicates parallel and normal to sulfide surfaces and as inclusions in sulfides; sulfur-rich veins transecting the sheet-silicate matrix; zoned carbonates and phosphates and sulfide and magnetite grains exhibiting embayment. The mineralogical evidence indicates alteration of accreted minerals by a fluid that evolved with time, leading to etching, dissolution and reprecipitation. Sulfide compositions indicate alteration at ~25 °C, similar to conditions inferred for asteroid (162173) Ryugu and Ivuna-type (CI) chondrite meteorites. The fluid probably evolved from neutral to alkaline, culminating with the precipitation of highly soluble salts. We conclude that Bennu’s protolith comprised mainly nanometre to micrometre silicates, with fewer chondrules and calcium–aluminium-rich inclusions than those of most chondrite groups.

The Jadar deposit (Serbia) is a unique end member of the volcano-sedimentary Li deposit class, where the main ore mineral is jadarite (LiNaSiB3O7(OH)), to date only recorded at the Jadar locality. We provide the first account of the features of the Jadar deposit based on the study of drill hole material, complemented by petrographic analysis, whole-rock, and isotopic geochemistry. The Li-B mineralization is hosted by sediments interlayered with tuffs that were deposited in a fault-bounded lacustrine basin. Mineralization processes initially involved alteration of volcanic glass through near-neutral and heated meteoric fluids, which resulted in the formation of hectorite. Lithium clays were later overprinted by higher-pH brines, which underwent significant evaporation, combined with conditions of Na+ and SiO2(aq) saturation, resulting in formation of siliceous gels that were the precursors to jadarite formation and extensive zeolitization of the intrabasinal sediments. Formation of jadarite occurred in two stages: (1) early diagenesis accompanied by zeolitization and precipitation of primary dolomite, which resulted in the sediment-hosted Li mineralization, (2) late remobilization of Li(B-Na)–saturated fluids, leading to formation of epigenetic jadarite-albite infills of fractured rocks. Isotopic geochemistry combined with mineral chemistry proxies indicate that early mineralizing processes were largely dominated by diagenetic fluids that experienced a thermal influence from the coeval cooling of the Miocene S-type granite member of the nearby Cer Mountain Complex. Late thermal maturation of organic matter then resulted in acidic fluids that dissolved the early ore assemblage and led to formation of late diagenetic lithiophosphate and low-Na borates.

Exceptional preservation of biogeochemical complexity in the Precambrian is largely limited to cherts, phosphates and shales; however, ancient fossils, including microbial mats and microbially induced sedimentary structures, also occur, more rarely, in poorly sorted, coarse-grained siliciclastics. The precise micromechanics by which exceptional retention of organic microbial traces occur within such rocks over billion-year geological timescales remain poorly understood. Herein, we explore the micro–nano-scale characteristics of microbial mats preserved in ~2.9 billion-year-old sandstones from the Mosquito Creek Formation (Pilbara, Australia) using a suite of advanced spatially correlated microscopy and geochemistry techniques. We demonstrate that sedimentary horizons rich in K–Al-phyllosilicates exhibit exceptional and unexpected preservation of biogeochemical complexity despite the age and metamorphic grade of the sequence. We propose that authigenic phyllosilicates intercalated with microbial kerogen at the nanoscale promote the preservation of nanoscopic domains of poorly ordered amorphous and turbostratic carbonaceous materials through pressure compensation associated with the kaolinite–illite transition during burial diagenesis and metamorphism, impeding the maturation of organic materials. Elucidating organic preservation in coarse-grained siliciclastics opens new avenues for biosignature searches both in ancient Earth sequences and on Mars, where similar phyllosilicate-bearing sandstones have been collected by the Mars 2020 Perseverance rover for near-future sample return.

While there is enormous interest in studying oxide perovskites with stoichiometries based upon or derived from ABO₃, including oxygen-deficient compositions and organometallics, other closely related topologies have been overlooked. Hydroxyperovskites are such a group. Their structures are perovskite-like octahedral frameworks with vacant cavity A sites, and all oxygen atoms form hydroxyl groups. There are fifteen naturally occurring hydroxyperovskites and numerous synthetic analogues. There are two stoichiometries: BB′(OH)₆ and B(OH)₃. The former consist of alternating divalent and tetravalent cations (B = Mg, Ca, Mn²⁺, Fe²⁺, Co²⁺, Cu²⁺, Zn; B′ = Sn, Ge). B(OH)₃ structures have only trivalent cations (Al, Fe³⁺, Ga). The properties and behavior of solid solutions in hydroxyperovskites are largely unexplored. This article summarizes our current knowledge of the crystallography and crystal chemistry of hydroxyperovskites and suggests productive areas of research in relation to their potential as functional materials. It should be evident that much of the findings remains to be discovered.

The main aim of this study was to investigate whether environmental or biological factors predominantly influence bryozoan biomineralization along the South African coast (spanning from 29.263°S; 16.87°E to 27.540°S; 32.677°E), a region known for its diverse oceanographic conditions. New data into the mineralogical (calcite vs. aragonite) and geochemical (Mg content in calcite) composition of bryozoans are provided, enhancing the global database and understanding of biomineralization patterns. To date, there has been a notable scarcity of data on bryozoan skeletal composition in tropical and subtropical regions, representing a significant gap in our knowledge and understanding of the impacts of climate change on marine, calcifying organisms. Our research reveals a diverse array of carbonate skeletons across nearly half of the known bryozoan species in the region, with calcitic forms dominating, followed by bimineralic and aragonite-based forms. The prevalence of aragonite-containing skeletons, particularly within the Cheilostomatida, mirrors global patterns, indicating a correlation with sea temperature gradients. Significant mineralogy and magnesium calcite variability exists within the Flustrina and Membraniporina suborders (Cheilostomatida). Despite exploring various environmental parameters such as temperature, salinity, or impact of currents (Agulhas, Benguela, or mixed), no clear correlation with mineralogical patterns emerged. Instead, the study underscores the substantial influence of biological control on bryozoan skeletal carbonate mineralogy and geochemistry. These findings highlight the importance of comprehensive, multi-parametric analyses to unravel environmental signals in bryozoan biomineralization, contributing to a deeper understanding of the impacts of climate and local conditions on marine calcifiers.

Aim: Quantify the contribution of environmental factors (water temperature, salinity and depth) and evolutionary history to varied skeletal mineralogy in calcifying marine organisms.Location: Global Ocean.Time period: Present.Major taxa studied: Order: Cheilostomatida; Phylum: Bryozoa.Methods: We employed X‐ray diffraction (XRD) to analyse the skeletal mineral composition of 872 individual colonies, representing 437 bryozoan species, in terms of calcite/aragonite ratios. We integrated these data with equivalent published data, thus reaching 981 species, and applied linear models (LMs), generalized linear models (GLMs) and phylogenetic generalized least squares models (PGLSs) to investigate the influences of temperature, salinity, depth and phylogenetic history on the mineralogy of nearly 1000 cheilostome bryozoan species.Results: Cheilostome bryozoans vary considerably in their skeletal mineral composition: in our dataset 65% of the species possess purely calcite skeletons, 15% exclusively employ aragonite and 20% exhibit mixed (i.e. calcite and aragonite) mineralogies. Temperature is the predominant measured environmental factor influencing bryozoan skeletal mineralogy, accounting for 20% of its variability across species, when phylogenetic relatedness is unaccounted for. Bryozoans in lower latitudes, characterized by higher seawater temperatures, have higher aragonite concentrations. By accounting for phylogenetic structure using a subset of 87 species for which we have topological information, 40% of the observed mineralogical variability could be attributed to present‐day temperature. In contrast, depth and salinity played minor roles, explaining less than 1% of the mineralogical variation each.Main conclusions: This study emphasizes the influence of evolutionary history on the mineralogical variability of calcifying organisms, even when it can be shown that a single environmental factor (temperature) explains a substantial amount of this variability. When confronted with changing temperature, calcifiers such as bryozoans are likely to respond in diverse ways, depending on the species, given their phylogenetic relatedness and the external conditions they meet.