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.

Phosphorus is essential for extant and nascent life. However, phosphate’s low terrestrial abundance and the poor aqueous solubility of phosphorus-bearing minerals pose major hurdles for prebiotic chemistry. Here, we show that silicate-phosphate immiscibility in volcanic melts could have provided a widely available mechanism for the local enrichment of phosphate. Starting with a phosphorus-enriched Archean melt, we observe that rapid cooling results in the formation of immiscible glassy droplets with up to 21 weight % phosphorus pentoxide, which can be delivered to the surface by volcanic processes. In aqueous leaching, we detect millimolar phosphate concentrations, which enable the synthesis of phosphorylating agents such as polyphosphates and imidazole phosphate with up to 34% yield. These results demonstrate how volcanic processes can enrich phosphate to fuel prebiotic chemistry.

The stratovolcano Mt. Pelée, Martinique, exhibits eruptive styles ranging from dome formation to sustained, highly violent explosive activity. Historical eruptions have produced lava domes and pyroclastic density currents, collectively termed Peléan activity. In pre-colonial times, several Plinian eruptions took place. Here, we explore physical controls on the proportions of fine particles produced—i.e., the fragmentation efficiency—during primary fragmentation. Samples were collected from ignimbrites from the 1929–1932 and 1902–1905 Peléan eruptions and the P1 (1300 CE), P2 (280 CE), and P3 (79 CE) Plinian eruptions. All samples are andesitic in bulk composition and contain a rhyolitic groundmass glass. The Peléan materials are more crystalline and less porous than their Plinian counterparts, a consequence of more extensive outgassing during dome formation. Representative blocks were cored and experimentally fragmented following rapid decompression (> 1 GPa·s⁻¹ from initial pressure between 5 and 20 MPa). Dry sieving allowed for determining grain size distributions, from which the fractal dimensions, D_f, were calculated as a quantification of fragmentation efficiency. Our results indicate different behaviors for Peléan and Plinian samples. While fragmentation efficiency is positively correlated with applied potential energy for Peléan samples, this relationship is not observed for the Plinian samples, possibly due to syn-fragmentation gas escape above a certain porosity. The rapid decompression experiments were designed to minimize secondary fragmentation by shear along the walls or impact while preserving the entirety of produced materials. Thus, our experimental grainsize data are physically linked to sample textures and overpressure. By comparison with natural pyroclastic products—commonly incompletely preserved—we can approach quantitatively constraining the energetic conditions underlying individual eruptions.

The movement of valves of bivalved invertebrates is enabled through the action of muscles and the interplay between the muscles and the hinge ligament. The muscles that move the valves attach to their internal surface. To promote the structural integrity at the mechanically mismatched interfaces, a specific crystal microstructure and texture are present at the muscle attachment sites. These are different from the crystal microstructure and texture of the rest of the valves. We present here for modern two- and three-layered brachiopod shells (Magellania venosa, Liothyrella neozelanica and Gryphus vitreus) the mode of crystal organisation at sites of adductor and diductor muscle attachments (i) relative to the microstructure and texture that forms the other sections of the valves and (ii) relative to crystal organisation of muscle attachment sites of bivalved invertebrates of other phyla, namely, species of the class Bivalvia. We discuss similarities/differences in Ca-carbonate phase, microstructure and texture between rhynchonellate brachiopods and bivalves, and discuss whether the Ca-carbonate crystal organisation of muscle attachment sites is convergent for bivalved marine organisms. We show significant differences in muscle attachment site architecture and highlight the different structural solutions developed by nature for shells of marine organisms that serve the same purpose.

Scaphopod molluscs are marine, infaunal, cosmopolitan animals. They encase their soft tissue with an aragonitic tusk-shaped shell that has at its two ends an orifice, the aperture and the apex. We investigated the shell of the dentaliid species Fissidentalium metivieri and Antalis weinkauffi and characterized shell crystal organization with electron backscatter diffraction (EBSD) and laser confocal and scanning electron microscopies. Based on crystal size, morphology, organization and growth-line spacing, we distinguish five different crystal arrangement motifs in the investigated shells. We find two slightly different microstructures for the shell proper, two microstructures for the attachment of muscles to the shell and one microstructure for a secondary hard tissue growth product, secreted at the apical orifice. Crystal organization motifs are crossed-lamellar, dendritic and prismatic. Crystal textures are crossed-lamellar, axial-like and crossed-lamellar-like. Crystal organization with a crossed arrangement is utilized for shell formation by representatives of many Ca-carbonate shell-secreting mollusc classes/subclasses: Scaphopoda, Gastropoda, Bivalvia, Polyplacophora (crossed-lamellar), and Patellogastropoda (crossed-foliated). Based on structural–crystallographic attributes, we highlight a basic shell structure that is broadly similar for the species of these mollusc classes/subclasses. However, this basic crystal arrangement motif is significantly modulated by the specific crystal organization that is inherent for a particular mollusc class/subclass.

Phosphorus is an essential element of life, as observable in modern life forms that have perfected phosphorus accumulation and recycling. Prebiotic chemistry, on the other hand, was likely challenged by the low abundance and poor solubility of phosphorus minerals on early Earth.Current experimental approaches to solve this so-called phosphate problem mainly focus on the solubilization of phosphate minerals like apatite or reduced phosphorus species in extraterrestrial schreibersite. However, the possibilities for prebiotic chemistry through magmatic evolution and phosphate enrichment in basaltic melts have not yet been considered.Here, we show the formation of phosphate-rich glass droplets, driven by liquid immiscibility in basaltic melts, and explore its downstream utilization for prebiotic chemistry. We synthesized two glasses mimicking an average composition of 2.2 – 3.8 Ga old basalts containing more than 0.5 wt.% phosphorus, and doped them with 1 and 10 wt.% P2O5 respectively. In the latter, unmixing lead to the formation of Fe-P-rich droplets in a Si-rich matrix with a partition coefficient of DP ~3.9. Subsequent leaching behavior of the synthesized glass was investigated over a range in pH and organic solvents delivering up to 5 mM dissolved phosphate. The concentration in the experimental leachate was sufficient to form di- and triphosphate afterwards at elevated temperatures and phosphorylation of adenosine was possible.We further found that our initially produced leachates were able to trigger the synthesis of imidazole phosphate with up to 34 % yield and the downstream phosphorylation of glycerol in wet/dry cycles with up to 17 % yield. Our results thus show an alternative source of phosphate for prebiotic chemistry through its early enrichment in the magma and present an alternative approach to solving the phosphate problem for the origin of life.