Abstract We report the discovery of the second (Al,Cu)‐alloy–bearing micrometeorite, FB‐A2, recovered from Mount Gariglione (southern Italy), representing the sixth such occurrence worldwide. Although chondritic in nature, FB‐A2 differs markedly from previously described microspherules. It is a scoriaceous micrometeorite dominated by silicates and contains a relict clast composed of Mg‐rich olivine and pyroxene phenocrysts set in a Fe‐rich silicate matrix. The particle rim hosts fine aggregates of phosphates, magnetite, Ni‐bearing magnetite, and sulfides, whereas the interior contains nepheline crystals. A 120 μm (Al,Cu)‐alloy grain occurs at one corner of the particle. The porphyritic texture of the clast indicates a chondrule fragment—the first identified in an (Al,Cu)‐bearing micrometeorite—while polyhedral sub‐grain boundaries and metal–sulfide veins record shock metamorphism. Iron‐rich alteration of relict silicates is consistent with high‐temperature (<560 °C) metasomatism typical of CV3 chondrites and is supported by oxygen isotope compositions close to the Carbonaceous Chondrite Anhydrous Mineral Line. Brecciation of chondrule olivine suggests impact‐induced fluid pressure excursions during early Solar System metasomatism, whereas impact melt enveloping elongate olivines indicates a later impact that introduced the (Al,Cu)‐alloys. Overall, the texture, mineralogy, and isotopic composition of FB‐A2 provide the most detailed constraints yet on the origin of (Al,Cu)‐bearing micrometeorites and confirm a genetic link to the Khatyrka meteorite.

The Trinity nuclear test of July 16, 1945, generated extreme transient conditions that produced trinitite, a silicate glass containing rare metallic phases. Here we report the discovery and structural and chemical characterization of a previously unknown Ca-Cu-Si type-I clathrate, (Ca3.3Cu0.4Fe0.3)Σ=4Si23, identified within a Cu-rich metallic droplet embedded in red trinitite. Single-crystal X-ray diffraction shows that this phase adopts the cubic clathrate-I topology, representing the first crystallographically confirmed clathrate structure documented among the solid-state products of a nuclear explosion. Beyond its intrinsic significance, this phase is notable for its close contextual association with the previously reported Si-rich icosahedral quasicrystal formed in the same detonation. Both phases formed under identical extreme conditions, occur within similar Cu-rich droplets, and share an unusually Si-rich Ca-Cu-Si-(Fe) chemistry, motivating an evaluation of whether the quasicrystal could be structurally derived from a clathrate framework. To evaluate this possibility, we performed density functional theory calculations on clathrate-based icosahedral models across a range of Cu contents. The results indicate that clathrate-derived icosahedral structures are mechanically plausible and metastable at low Cu concentrations (~10 to 11%) but become unstable as Cu content approaches that of the Trinity quasicrystal. These findings constrain viable structural models for the quasicrystal and argue against a simple clathrate-derived interpretation.

Here we present the first single-crystal X-ray diffraction analysis of zolenskyite, a chromium-bearing sulfide mineral (FeCr2S4) and newly identified polymorph of daubr & eacute;elite, discovered in the Muonionalusta meteorite, a well-characterized IVA iron meteorite. Zolenskyite occurs as rare micron-scale grains associated closely with daubr & eacute;elite and stishovite, within a troilite matrix. Chemical analysis confirms a pure, homogeneous FeCr2S4 composition. The crystal structure was refined in the monoclinic C2/m space group, revealing a framework of face-sharing octahedra, consistent with a cation-deficient NiAs-type structure, distinct from the spinel-type structure of daubr & eacute;elite. Zolenskyite forms under high-pressure (>7 GPa) and high-temperature (>1000 K) conditions, probably through solid-state transformation from daubr & eacute;elite during shock events. The serendipitous recognition of zolenskyite emphasizes the value of careful micron-scale mineralogical investigations in revealing transient or metastable phases that record otherwise inaccessible physicochemical conditions. These findings contribute to understanding the thermal and shock history of meteorite parent bodies and the stability of Fe-Cr sulfides in extraterrestrial environments.

High-energy nuclear detonations generate extreme, transient physicochemical environments capable of producing previously unknown materials. We report the discovery of a previously unknown multicomponent alloy preserved within a hiroshimaite spherule recovered from beach sands of Hiroshima Bay, formed during the 6 August 1945 atomic airburst. The micrometer-sized metallic grain occurs within a quenched glassy matrix. Electron microprobe analyses reveal a homogeneous, Si-rich multielement composition (Fe-Cr-Ni-Mn-Mo-Si-Al). Single-crystal x-ray diffraction shows that the phase crystallizes in space group P213 with the ordered AlAu4-type structure, an ordered derivative of β-Mn. The alloy likely formed by condensation from a mixed metallic vapor followed by ultrafast quenching in the expanding fireball. This finding demonstrates that nuclear plasma events may stabilize complex metallic phases and highlights atomic-blast debris as a natural laboratory for nonequilibrium alloy formation and materials discovery.

Iron silicides, including hapkeite (Fe2Si), are rare minerals found in both terrestrial and extraterrestrial environments. In this study, we present the discovery of trigonal Fe2Si in glass from the Blackville site, South Carolina, USA, in a discrete, deeply buried layer where it is associated with suessite and other impact-related materials. The site has been previously studied for its rich assemblage of Fe-Si spherules, platinum, iridium and nanodiamonds. Using advanced micro-computed tomography, scanning electron microscopy, electron microprobe analysis, and single-crystal X-ray diffraction, we have characterised the crystal structure of trigonal Fe2Si, identifying it as a distinct phase from the cubic hapkeite. The high concentrations of V, Ti and P in trigonal Fe2Si and its co-occurrence with suessite suggest an impact-related origin or a lightning strike. Anthropogenic processes, although unlikely, cannot yet be completely ruled out. While this compound represents a new polymorph of Fe2Si, we refrain at this time from proposing it as a new mineral species to the International Mineralogical Association (IMA) because of remaining uncertainties about its formation. Further research is needed to determine whether this trigonal Fe2Si was produced by natural processes or by anthropogenesis.

This paper argues that modern science is undergoing a fundamental shift from direct observation to inference-based reconstruction of inaccessible systems. Using the Event Horizon Telescope’s imaging of a black hole as a paradigm, it highlights how knowledge increasingly emerges from integrating fragmented, indirect signals within computational and theoretical frameworks. Extending this perspective to geoscience, the author proposes a global “Earth Telescope” – a distributed, multi-sensor system capable of reconstructing the dynamic, four-dimensional structure of the Earth’s interior from heterogeneous data. The paper further draws connections with the discovery of natural quasicrystals, which form under extreme, non-equilibrium conditions and encode information about high-energy cosmic processes. Across astrophysics, geophysics, and materials science, a shared epistemology emerges: the extraction of structure from transformed signals through inversion and modelling. This convergence suggests that cross-disciplinary methods can advance the study of extreme environments across scales. Ultimately, the author advocates for an integrative, multiscale approach to science, positioning the Earth as part of a broader cosmic continuum and arguing that innovations such as an Earth Telescope could transform our understanding of planetary dynamics and the evolution of matter in the Universe.

Pyrochlores, general formula A(2-m)B(2)X(6-w)Y(1-n) and cubic Fd (3) over barm (Z = 8) symmetry, are oxide and fluoride minerals with a peculiar structure consisting of a framework of corner-linked BX6 octahedra. The framework is arranged such that it forms tunnels parallel to the [110] direction, which are occupied by the A and Y sites at the centre (or in slightly displaced neighbouring positions). Atoms hosted at the tunnel sites are particularly susceptible to ion-exchange processes, especially when these sites are occupied by highly mobile species (e.g. water) or are partially vacant; this is the case for hydropyrochlore and hydrokenopyrochlore from the Lueshe carbonatite, both extensively altered and hydrated due to intense weathering. Their ion-exchange properties are remarkable, making them suitable candidates for Tl+ sequestration from aqueous matrices. This study focuses on the kinetics of the ion-exchange reaction involving monovalent thallium, incorporated by single crystals through progressively longer imbibition experiments in Tl-rich solutions. Structural (single-crystal X-ray diffraction) and chemical (electron microprobe analysis) investigations carried out before and after each imbibition experiment showed that Tl+ is incorporated in the structure at both tunnel sites and tends to order preferentially at A with increasing A:B occupancy ratios. The entry of Tl+ seems to be accompanied by a progressive shift in colour of the crystals (from colourless to dark brown). The incorporation process is relatively quick, as it approaches a saturation limit (similar to 70-75% of the A site occupancy) in, cumulatively, 450 minutes of treatment; longer imbibition experiments (930 minutes) only led to a slight redistribution of electrons among the tunnel sites.

Quasicrystals, materials with long-range order but no periodicity, were first discovered in nature within the Khatyrka meteorite, a CV3 carbonaceous chondrite. Their occurrence demonstrated that hypervelocity impacts can generate quasiperiodic phases under transient conditions far from equilibrium, which survived for billions of years. Icosahedral and decagonal quasicrystals from Khatyrka formed at pressures exceeding 5 GPa and temperatures above 1200°C, as shown by their microstructures and association with shock-melted silicates and high-pressure polymorphs. Laboratory shock-recovery experiments reproduced these phases, confirming their synthesis during microsecond-scale shock pulses and their persistence after release. The presence of metallic aluminium, rarely stabilized in natural systems, indicates that extreme redox conditions are transiently established during impacts, enabling unusual alloy chemistries. Although rare in the meteoritic record, quasicrystals may be more widespread, their scarcity reflecting preservation biases and limited analytical focus on metallic phases. Advanced nanoscale diffraction and tomography methods, coupled with systematic surveys, are essential to uncover their distribution. Beyond meteorites, terrestrial craters, lunar breccias, Martian meteorites and asteroid samples are promising targets. Quasicrystals thus represent durable witnesses of impact processes, expanding the mineralogical tools for tracing high-energy events that shaped the early solar system.

Quasicrystals have structural properties intermediate between crystalline and amorphous materials. They can be synthesized in the lab but, as Luca Bindi explains, they may also be present in natural materials formed under extreme conditions.

Mineralogical crystallography has evolved from the geometric and observational studies of the eighteenth century to a dynamic, predictive science capable of probing matter at atomic and nano-scales. Contemporary advances, including ultrafast X-ray free-electron lasers, high-pressure diamond anvil cells, cryo- and environmental electron microscopy, and multimodal in situ techniques, now permit real-time observation of mineral transformations under extreme conditions. Coupled with computational modelling and predictive simulations, these methods are transforming crystallography into an integrative, interdisciplinary discipline with applications ranging from Earth and planetary sciences to materials engineering. This essay explores technological innovations and emerging frontiers of mineralogical crystallography, highlighting its enduring role in revealing the hidden architectures of matter and guiding the exploration of both natural and synthetic materials.

The Suizhou meteorite is a heavily shock-metamorphosed L6 chondrite which contains thin shock melt veins. So far, 26 high-pressure phases have been identified from the meteorite. Among the high-pressure phases, ten of them were approved as new minerals which include tuite, xieite, wangdaodeite, chenmingite, hemleyite, poirierite, asimowite, hiroseite, elgoresyite, and ohtaniite, by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association. Other high-pressure phases identified from the meteorite are ahrensite, akimotoite, bridgmanite, lingunite, magnesiowüstite, majorite, majorite–pyropess, maskelynite, riesite, ringwoodite, wadsleyite, and 5 other phases including phase A, vitrified phase B and phase C, phase D (Ca-rich majorite), and partly inverted ringwoodite. The occurrence and abundance of high-pressure phases makes this meteorite the one with the richest variety of high-pressure minerals to date.

The investigation of mineral inclusions in diamonds represents a unique tool to better understand the mineralogy and composition of hidden portions of Earth's mantle and, hence, determine conditions of pressure and temperature at the time of diamond formation. Using a combination of experimental techniques and different geothermobarometric approaches, we characterized a natural diamond from Udachnaya kimberlite pipe entrapping nine inclusions; the inclusions are five garnets, three clinopyroxene and one sulfide and represent an eclogitic paragenesis. Here, we adopted, for the first time, the elastic geobarometry method to the garnetdiamond inclusion-host system to calculate the entrapment conditions for the diamond-garnet pair, resulting in 5.7(+/- 0.3) GPa at 1154 degrees C. These P-T data are compared with estimates obtained through chemical geothermobarometry, employing T projection onto the local geotherm, a common approach used for eclogite xenoliths in absence of robust calibrated barometers. Our data demonstrate that elastic geobarometry for the garnet-diamond pair results to be a very reliable tool to determine the diamond formation also for eclogitic systems and this will allow to expand our knowledge on eclogitic diamonds in terms of depth of formation.

& Aring;sgruvanite-(Ce), ideally Ce16Ca5Al(SiO4)6(AsO3)8(CO3)2Cl3(ClF3)(OH)2, is a new mineral species (IMA-CNMNC 2025-004) from the & Aring;sgruvan Fe-skarn deposit, Norberg, V & auml;stmanland, Sweden, which is directly related to the Bastn & auml;s type of rare earth element (REE) mineralisations in the Palaeoproterozoic Bergslagen ore province. & Aring;sgruvanite-(Ce) occurs as anhedral, occasionally elongated grains up to 400 mu m. It is greyish green to nearly colourless, with a white streak and a vitreous to greasy lustre. Cleavage is distinct on {001} and less so on {100}; the mineral is brittle, and its fracture is uneven. The calculated density is 4.79(1) g cm-3. & Aring;sgruvanite-(Ce) is optically uniaxial (+), with a refractive index above 1.8; the calculated average is 1.88 (Gladstone-Dale approach). & Aring;sgruvanite-(Ce) crystallises in the trigonal system in space group P-3m1 (Z=1), with the following unit cell parameters: a=10.5728(6) & Aring; and c=15.0899(11) & Aring;. & Aring;sgruvanite-(Ce) occurs in a magnetite-REE skarn, but its formation postdates the groundmass carbonate and skarn assemblage, and it is associated with late-stage calcite, dolomite, a dollaseite-like allanite group mineral, gadolinite-(Y/Nd), and a fluorocarbonate related to bastn & auml;site-(Ce), with variable F contents. The structure was refined to R1=6.23 % for 987 reflections. It is unique and consists of two alternating layers, A and B, along the c axis. Layer A (similar to 8.4 & Aring;) has the composition [(Ce12Ca3)AlSi6(C1.50S0.50)Sigma 2.00O30(OH)2]15+. Layer B (similar to 6.7 & Aring;) corresponds to the composition [(Ce4Ca2)As83+O24Cl4F3]15-. These layers form tunnel-like features parallel to [100], which are partially occupied by Cl atoms. Spectroscopic data (infrared and micro-Raman) support the structural model.

Natural quasicrystals, compounds with characteristics intermediate between crystalline material and glass, have been so far discovered in extraterrestrial materials only. Furthermore, their occurrence in nature is limited to metallic, Al-bearing alloys. The presence of metallic aluminum in these minerals raised doubts about their potential occurrence in terrestrial rocks. The geochemical conditions needed to form metallic Al are so reducing that they are considered very unlikely in a terrestrial environment. Given the report of dodecagonal symmetry in the synthetic Ta1.6Te quasicrystal, the search for terrestrial quasicrystals was focused on natural tellurides.Here, we report the discovery of the first terrestrial approximant of a dodecagonal quasicrystal, a Pd-Ni-telluride with formula Pd3Ni4Te8 and tetragonal symmetry, which was found as small inclusions in a rock sample from Kalgoorlie, Western Australia. Periodic approximants are crystalline materials that share a similar chemical composition with quasicrystals but have a slightly altered atomic structure, aligning their symmetry with the traditional principles of three-dimensional crystallography. These crystalline approximants provide insights into the local atomic structure of their corresponding quasicrystals.Natural Pd3Ni4Te8 has been approved as a new mineral by the International Mineralogical Association with the name proxitwelvefoldite (IMA 2024-034). The Pd3Ni4Te8 composition has never been reported to form quasicrystal approximants among synthetic products and could indicate the possible existence of a 12-fold quasicrystal in the Pd-Ni-Te system. The discovery points to the possibility that the quasicrystalline structure may be much more common than previously thought, even in non-alloy systems.

This study investigates the magma plumbing system of the Miocene volcano shield stage of Tenerife (Canary Islands) through a geothermobarometric analysis of clinopyroxenes in ankaramite dykes and lavas from the Teno and Roque del Conde massifs. Ankaramites, characterized by a high phenocryst content of olivine and clinopyroxene, provide valuable insights into magma storage and transport processes. Two different methods have been applied to estimate the pressure and temperature of crystallization of clinopyroxenes: (i) a novel machine learning geothermobarometer and (ii) a geobarometer that uses their structural parameters (Vcell and VM1 polyhedron). The results yielded a pressure distribution between 0 and 8 kbar with a difference between clinopyroxene cores and rims, reflecting a multi-level plumbing system with evidence for the progressive ascent and crystallization of magmas. Further considerations of aluminium incorporation into the tetrahedral site and zonation patterns of clinopyroxene cores revealed three groups with distinct P-T paths, which are Low-T, High-T, and Low-P clinopyroxenes. Low-T clinopyroxenes are the largest ones (up to few centimetres in size) and exhibit resorbed and patchy zonation. This group represents a relatively cold crystal mush formed from a more hydrated magma, accumulated during a long residence time in disequilibrium conditions, as testified by crystal habits. High-T clinopyroxenes show normal zonation pattern and consist of small crystals (1-2 mm in size) directly crystallized from a less hydrated carrier magma during its ascent from depth (> 20 km b.s.l.). This magma, which tore away part of the crystal mush bodies, acted as the transport agent of these two suites of crystals up to the shallower crustal reservoirs (0-7 km). At these depths, clinopyroxene cores of the Low-P group crystallized in the same P-T conditions as those of the rim domain, in a chemical disequilibrium regime, proved by resorbed and patchy textures. In this scenario, ankaramites witness the occurrence of a heterogeneous cargo of clinopyroxenes that formed at different depths in the plumbing system of the Teno and Roque del Conde massifs during the volcano shield stage. The results of our research extend previous geothermobarometric studies and refine the understanding of the ankaramite plumbing system of Tenerife. Our data are consistent with the plumbing systems of other shield volcanoes of the Canary Islands and Hawaii and boost the application of machine learning approaches in revealing the anatomy of volcano plumbing systems.

Fulgurites are natural glasses that form when lightning strikes sand, soil, or rock and fuses the individual grains together to generate what is usually a tubular structure that follows the path of the strike. During this process, localised reducing conditions are conducive to forming rare minerals including iron silicides. This paper examines a fulgurite formed in Southwick, Massachusetts, USA, which displays an iron silicide that has a clearly defined reaction rim. The reaction rim demonstrates the production of a more silicon-rich rind consisting of Fe5Si3 on a core of Fe2Si, and the most likely route to forming this material is by reaction of silicon gas with Fe2Si at high temperature (>1000 degrees C), with a reaction timescale of about one second. This reaction suggests the high temperature, reducing conditions of a lightning strike favour reactions of condensed matter (e.g. liquid or solid iron minerals) with gas that occurs rapidly during the lightning strike. The conditions necessary to form these minerals suggest that the fulgurite became more reducing over time, as more Si entered the solid phase, perhaps as oxygen left the system, either as CO2 or from the breakdown of SiO2 gas.

Vargite, ideally MnCu2Mn2(OH)4(H2O)4(AsO4)2 - named after the Swedish miner Erik Gustaf Varg (1886-1970), who collected the type specimen - was found in the L & aring;ngban Fe-Mn deposit. It occurs in open cavities in a brecciated and later hydrothermally leached carbonate groundmass, in association with hausmannite, calcite, rhodochrosite, baryte, a serpentine-group mineral, and galena. Additional minor phases are hedyphane, phlogopite and yarrowite. Paragenetically, it is a late-stage mineral, formed as a result of the interaction between an As-rich hydrothermal fluid and Mn-oxide(s) and Cu-sulphide, under low P- and T-conditions. Vargite forms bright green, semi-spherical aggregates up to 0.5 mm across, consisting of numerous thin, lath-shaped crystals, elongated along [100] and with a maximum length of 200 mu m. Mohs hardness is approximate to 3 and Dcalc = 3.49(1) gcm-3. The empirical chemical formula obtained from electron probe micro-analyses analyses and based on 16 anions is (Cu1.77Mg0.33)Sigma 2.10(Mn2.94Ca0.04Pb0.01)Sigma 2.99(As1.95Si0.02)Sigma 1.97O8(OH)4.033.98H2O. The crystal structures of vargite and the isotypic mineral akrochordite [MnMn2Mn2(OH)4(H2O)4(AsO4)2] have been refined in the space group P21/c from single-crystal X-ray diffraction data to R1 = 3.07% and 2.46%, respectively, giving the following sets of unit-cell parameters: a = 5.6251(14), 5.6832(11) & Aring;, b = 17.452(5), 17.631(5) & Aring;, c = 6.905(2), 6.8417(19) & Aring;, beta = 100.21(5)degrees, 99.51(4)degrees, and V = 667.2(3), 676.1(3) & Aring;3, with Z = 2. A Raman spectrum of vargite, with major bands at 3510, 1610, 850, 780, 476, 428, 389, and 308 cm-1, strongly resembles that of isotypic guanacoite, [MgCu2Mg2(OH)4(H2O)4(AsO4)2]. Vargite, akrochordite, and guanacoite constitute the newly established akrochordite group.

Exceptionally well-developed crystals of akaganeite, (Fe3+,Ni2+)(8)(OH,O)(16)Cl-1.25nH(2)O, were observed during the investigation of rust samples from the Muonionalusta iron meteorite, constituting ideal candidates for the first single-crystal X-ray diffraction investigation carried out on this mineral. Other techniques here employed to study akaganeite include SEM-EDS and Raman spectroscopy. The structure refinement (R1 = 2.23%) confirmed akaganeite to be monoclinic in symmetry (space group I2/m), with a = 10.560(4) & Aring;, b = 3.0268(12) & Aring;, c = 10.512(4) & Aring;, beta = 90.050(15)degrees and V = 336.0(2) & Aring;(3). The mineral is also confirmed to be isostructural with monoclinic members of the hollandite supergroup, with 2 x 2 tunnels parallel to the b axis constituted by edge-linked Fe-octahedral chains. Chemical analyses resulted in a Cl range of 2.8-5.6 wt.% and an average mole Fe/Cl ratio of 7.6, with trace amounts of Si, Al and S (< 0.1 wt.%), and no detectable Ni or Co. The combination of structural and chemical data yielded the stoichiometric formula Fe8O7(OH)(9)Cl. The Raman spectrum of the Muonionalusta akaganeite is comparable with Raman spectra from synthetic akaganeite, showing several peaks between 138 and 1390 cm(-1) and the O-H stretching band at 3510 cm(-1); no peaks are observed in the H2O bending-mode area of the spectrum, in keeping with the structural data. Taking into account all the collected data, we propose two possible new formulae for akaganeite (Z = 8): FeO1-x(OH)(1+x)Cl-x (0.01 < x < 0.20) or, taking Ni into account, (Fe1-xNix)O1-x-y(OH)(1+x+y)Cl-y (0 < x < 0.19 and 0.01 < y < 0.20). In the Muonionalusta corrosion rust, in addition to akaganeite, nickel-bearing humboldtine [Fe(C2O4)2H(2)O] was also identified through Raman spectroscopy, powder X-ray diffraction and chemical analyses. It possibly represents the first occurrence of an oxalate mineral as a product of terrestrial weathering of a meteorite.