Hasil untuk "Mineralogy"

D. Lauretta, H. McSween

Estrid Buhl Naver, Katrine Wulff Nikolajsen, Martin Sæbye Carøe et al.

The next great leap in Martian exploration will be the return of samples to Earth. To ensure the maximum scientific return from studying these samples, the development and utilisation of nondestructive analytical techniques are essential to enable early three-dimensional characterisation of their interiors. Neutron computed tomography is a powerful method in this context: it is highly sensitive to hydrogen and complements the more conventional X-ray computed tomography. Because the distribution and nature of hydrous phases are central to understanding the habitability, the climatic and geological evolution, and potential biosignatures of Mars, identifying hydrogenbearing phases in Martian crustal rocks is of particular importance. Using the only Martian crustal material available on Earth, the NWA 7034 meteorite and its pairs, we show that combined neutron and X-ray computed tomography enables non-destructive sample-wide mapping of hydrogen and reveals the distribution and petrographic contexts of hydrous phases. We identify hydrogen-rich iron oxyhydroxides within ancient igneous clasts, forming a macroscopic mineralogical water reservoir within the meteorite. These alteration assemblages closely resemble those observed in samples collected by the Perseverance rover in Jezero crater, where hydrated iron oxyhydroxides are also present. This similarity suggests that such phases may represent a widespread near-surface water reservoir on early Mars.

Rumyana Eneva, Stephan Engibarov, Irina Lazarkevich et al.

Nanotechnology has emerged as a promising option in combating the worsening situation with antibiotic resistance. We studied the antimicrobial effectiveness of four types of green synthesized zinc oxide nanoparticles (ZnO-NPs), obtained via Pluronic-assisted co-precipitation by lavender and thyme essential oils and their praseodymium-doped variants. Resazurin Microtiter Assay was applied to a panel of Gram-positive and Gram-negative bacteria from Risk 1 and 2 groups and the ESKAPE group. In relation to the pro-oxidative features of the ZnO-NPs, the production of superoxide dismutase (SOD) and catalase (CAT) in the tested microorganisms was also investigated, as these enzymes are important participants in the antioxidant defense of the bacterial cell and are considered virulence factors. We hypothesized that the sensitivity of microorganisms to the action of ZnO-NPs is related to their innate levels of antioxidant enzyme activity. The results showed that all types of studied ZnO-NPs had an antibacterial effect against the entire panel of tested strains, but with different potencies. The strongest effect was found for <i>Arthrobacter nicotianae</i>, <i>Oerskovia paurometabola</i>, <i>Bacillus subtilis</i>, and <i>Escherichia coli</i>. Less inhibition was observed for bacteria from Risk group 2 maybe due to their better antioxidant protection, especially for <i>Pseudomonas aeruginosa</i>. Praseodymium doping contributed to enhancing the bactericidal effect. A correlation between susceptibility of bacteria to ZnO-NPs and their antioxidant enzyme activity was observed.

Sara Capriotti, Alessio Devoto, Simone Scardapane et al.

Classification of ceramic thin sections is fundamental for understanding ancient pottery production techniques, provenance, and trade networks. Although effective, traditional petrographic analysis is time-consuming. This study explores the application of deep learning models, specifically Convolutional Neural Networks (CNNs) and Vision Transformers (ViTs), as complementary tools to support the classification of Levantine ceramics based on their petrographic fabrics. A dataset of 1,424 thin section images from 178 ceramic samples belonging to several archaeological sites across the Levantine area, mostly from the Bronze Age, with few samples dating to the Iron Age, was used to train and evaluate these models. The results demonstrate that transfer learning significantly improves classification performance, with a ResNet18 model achieving 92.11% accuracy and a ViT reaching 88.34%. Explainability techniques, including Guided Grad-CAM and attention maps, were applied to interpret and visualize the models' decisions, revealing that both CNNs and ViTs successfully focus on key mineralogical features for the classification of the samples into their respective petrographic fabrics. These findings highlight the potential of explainable AI in archaeometric studies, providing a reproducible and efficient methodology for ceramic analysis while maintaining transparency in model decision-making.

Josep M. Trigo-Rodríguez, Pau Grèbol-Tomàs, Jordi Ibáñez-Insa et al.

Undifferentiated asteroids, particularly the parent bodies of carbon-rich chondrite groups, might be promising candidates for future space resource utilization due to their primitive composition and potential to host valuable metals and rare earth elements. However, our understanding of their bulk elemental composition remains limited, as most data are derived from reflectance spectra with low mineralogical resolution. Sample return missions have started to change that, as returned materials are already available to study. Still the available meteorites provide a valuable source of information about the diversity of undifferentiated asteroids in the interplanetary space. To improve compositional insights, we conducted Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and ICP-AES (Inductively coupled Plasma Atomic Emission Spectroscopy) analyses on a representative suite of carbonaceous chondrites. These meteorites, considered analogs of undifferentiated asteroids, preserve materials from the early solar system and provide a geochemical record of their parent bodies. Our results highlight the abundance and distribution of transition metals, siderophile elements, and rare earth elements across several chondrite groups. These findings support the view that C-type asteroids may serve as viable sources of critical materials, while also informing future mission planning, extraction strategies, and the development of new technologies for low-gravity resource operations.

J. Farihi, K. Y. L. Su, C. Melis et al.

This letter reports 12 novel spectroscopic detections of warm circumstellar dust orbiting polluted white dwarfs using JWST MIRI. The disks span two orders of magnitude in fractional infrared brightness and more than double the number of white dwarf dust spectra available for mineralogical study. Among the highlights are: i) the two most subtle infrared excesses yet detected, ii) the strongest silicate emission features known for any debris disk orbiting any main-sequence or white dwarf star, iii) one disk with a thermal continuum but no silicate emission, and iv) three sources with likely spectral signatures of silica glass. The near ubiquity of solid-state emission requires small dust grains that are optically thin, and thus must be replenished on year-to-decade timescales by ongoing collisions. The disk exhibiting a featureless continuum can only be fit by dust temperatures in excess of 2000K, implying highly refractory material comprised of large particles, or non-silicate mineral species. If confirmed, the glassy silica orbiting three stars could be indicative of high-temperature processes and subsequent rapid cooling, such as occur in high-velocity impacts or vulcanism. These detections have been enabled by the unprecedented sensitivity of MIRI LRS spectroscopy and highlight the capability and potential for further observations in future cycles.

Yanick Ricard, Frédéric Chambat

Condensed planets contract or expand as their temperature changes. With the exception of the effect of phase changes, this phenomenon is generally interpreted as being solely related to the thermal expansivity of the planet's components. However, changes in density affect pressure and gravity and, consequently, the planet's compressibility. A planet's radius is also linked to its rate of rotation. Here again, changes in pressure, gravity and compressibility are coupled. In this article we clarify how the radius of a condensed planet changes with temperature and rotation, using a simple and rigorous thermodynamic model. We consider condensed materials to obey a simple equation of state which generalizes a polytopic EoS as temperature varies. Using this equation, we build simple models of condensed planet's interiors including exoplanets, derive their mass-radius relationships, and study the dependence of their radius with temperature and rotation rate. We show that it depends crucially on the value of $ρ_s g R/K_s$ ($ρ_s$ being surface density, $g$ gravity, $R$ radius, $K_s$ surface incompressibility). This non-dimensional number is also the ratio of the dissipation number which appears in compressible convection and the Gruneïsen mineralogic parameter. While the radius of small planets depends on temperature, this is not the case for large planets with large dissipation numbers; Earth and a super-Earth like CoRoT-7b are in something of an intermediate state, with a moderately temperature-dependent radius. Similarly, while the radius of these two planets are functions of their rotation rates, this is not the case for smaller or larger planets.

Marko Bermanec, Noa Vidović, Liubomyr Gavryliv et al.

Abstract Crystal structures of minerals are defined by a specific atomic arrangement within the unit‐cell, which follows the laws of symmetry specific to each crystal system. The causes for a mineral to crystallize in a given crystal system have been the subject of many studies showing their dependency on different formation conditions, such as the presence of aqueous fluids, biotic activity and many others. Different attempts have been made to quantify and interpret the information that we can gather from studying crystal symmetry and its distribution in the mineral kingdom. However, these methods are mostly outdated or at least not compatible for use on large datasets available today. Therefore, a revision of symmetry index calculation has been made in accordance with the growing understanding of mineral species and their characteristics. In the gathered data, we observe a gradual but significant decrease in crystal symmetry through the stages of mineral evolution, from the formation of the solar system to modern day. However, this decrease is neither uniform nor linear, which provides further implications for mineral evolution from the viewpoint of crystal symmetry. The temporal distribution of minerals based on the number of essential elements in their chemical formulae and their symmetry index has been calculated and compared to explore their behaviour. Minerals with four to eight essential elements have the lowest average symmetry index, while being the most abundant throughout all stages of mineral evolution. There are many open questions, including those pertaining to whether or not biological activity on Earth has influenced the observed decrease in mineral symmetry through time and whether or not the trajectory of planetary evolution of a geologically active body is one of decreasing mineral symmetry/increasing complexity.

Ariesky Martínez-Figueredo, Petr Alexéyevich Ignátov

Se identificaron las áreas con potencial para albergar depósitos de arcillas en la provincia de las Tunas, mediante la combinación de datos obtenidos por teledetección e información geológica integrada en el Sistema de Información Geográfica (SIG). Se utilizaron técnicas de mapeo geológico, de teledetección y modelado geoespacial. Los hallazgos revelaron una distribución heterogénea de zonas con moderadas, altas y muy altas potencialidades para albergar depósitos de arcillas en toda la región, con concentraciones significativas en los municipios Manatí, Tunas, Jobabo, Colombia y Amancio. La integración de datos obtenidos por teledetección y fuentes geológicas en un entorno SIG ha demostrado ser eficaz y viable para este tipo de análisis.

Rusi Rusew, Mariya Georgieva, Vanya Kurteva et al.

This study demonstrates the synthesis of five novel quaternary ammonium aldimines through a two-step synthetic route involving a condensation reaction between 4-pyridincarboxyaldehyde and 3,4,5-trimethoxyaniline, followed by the quaternization of the pyridine N-atom with various aromatic α-bromo ketones. The newly obtained compounds underwent characterization for both purity and molecular structure, utilizing HR-MS, 1D, and 2D NMR spectroscopy in solution, as well as a comparison between single-crystal and powder X-ray analyses in a solid state. The thermal behavior of the studied compounds was evaluated using differential scanning calorimetry (DSC). The antioxidant properties of the compounds were assessed through DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and ferric-reducing antioxidant power (FRAP) assays, employing Trolox as a standard. The performed in vitro antibacterial screening indicates a selective antibacterial activity against Gram-negative <i>K. pneumoniae</i> and <i>P. aeruginosa</i>, while no such activity is detected for Gram-negative <i>E. coli</i> and Gram-positive <i>S. aureus</i>.

P. Schneider, D. Balen

<p>Micro-Raman spectroscopy was used to determine the inclusions in magmatic zircon from the Late Cretaceous A-type acid igneous rocks in the Slavonian mountains (Mt. Papuk and Mt. Požeška Gora), in the southwestern part of the Pannonian Basin (Croatia). The mineral inclusions detected in the early-crystallised zircon are anatase, apatite, hematite, ilmenite and possibly magnetite. Numerous melt inclusions comprise albite, cristobalite, hematite, kaolinite, K-feldspar, kokchetavite, kumdykolite muscovite and quartz, where this mineral association is characteristic of so-called nanorocks (nanogranites), commonly found in peritectic garnets from high-grade metamorphic rocks. Here we present the first finding of kokchetavite and kumdykolite in a magmatic zircon. Together with anatase and hematite, these polymorphs are likely evidence of rapid uplift and consequent rapid cooling of hot oxidised magma generated in the lower crust and its emplacement in the upper crustal level. This finding provides further confirmation that kumdykolite and kokchetavite do not require ultra-high pressure (UHP) to form and should not be considered exclusively UHP phases. The rapid uplift was possible due to the formation of accompanying extensional deep rifts during the tectonic transition from compression to extension, associated with the closure of the Neotethys Ocean in the area of present-day Slavonian mountains in the Late Cretaceous (<span class="inline-formula">∼82</span> Ma).</p>

Yuan Wang, Jing Li, Yang Lin et al.

Black shales have attracted the attention of numerous researchers not only due to their high potential as hydrocarbon source rocks and shale gas reservoirs, but also to the enrichment of critical metal elements in black shale series. Black shale of the Cambrian Shuijingtuo Formation is one of the most important black shales in the Yangtze platform. This paper conducts integrated research on the mineralogical and geochemical characteristics of this black shale from the Luojiacun section in Western Hubei Region, aiming at elaborating the enrichment mechanism of elevated critical metal elements in the Shuijingtuo black shale. Minerals in the Shuijingtuo black shale are predominantly composed of quartz (avg. 43.0%) and clay minerals (avg. 32.5%), with small proportions of calcite, albite, clinochlore, and pyrite. The Shuijingtuo black shale is characterized by high total organic carbon (TOC, avg. 3.9%) content and enriched in V-Ni-Cr-U and Sr-Ba critical metal assemblages. The elevated V, Cr, Ni, and U present dominant organic affinities, while Sr and Ba are closely correlated to calcite and pyrite, respectively. The enrichment of V-Cr-Ni-U critical element assemblages in Shuijingtuo black shale are ascribed to the high primary productivity, anoxic depositional conditions, marine biologic production, and low-temperature hydrothermal activities. The enrichment of Sr and Ba is related to the high primary productivity and anoxic depositional conditions, respectively.

Marc-Antoine Fortin, Esteban Gazel, Lisa Kaltenegger et al.

The recent first measurements of the reflection of the surface of a lava world provides an unprecedented opportunity to investigate different stages of rocky planet evolution. The spectral features of the surfaces of rocky lava world exoplanets give insights into their evolution, mantle composition and inner workings. However, no database exists yet that contains spectral reflectivity and emission of a wide range of potential exoplanet surface materials. Here we first synthesized 16 potential exoplanet surfaces, spanning a wide range of chemical compositions based on potential mantle material guided by the metallicity of different host stars. Then we measured their infrared reflection spectrum (2.5 - 28 μm, 350 - 4000 cm^{-1}), from which we can obtain their emission spectra and establish the link between the composition and a strong spectral feature at 8 μm, the Christiansen feature (CF). Our analysis suggests a new multi-component composition relationship with the CF, as well as a correlation with the silica content of the exoplanet mantle. We also report the mineralogies of our materials as possibilities for that of lava worlds. This database is a tool to aid in the interpretation of future spectra of lava worlds that will be collected by the James Webb Space Telescope and future missions

Stefano Spadaccia, C. H. Lucas Patty, Holly L. Capelo et al.

Polarization phase curves of asteroids and other small airless bodies are influenced by the compositional and physical properties of their regolith. The mixing of minerals composing the regolith influences the negative polarization at small phase angles because it changes the multiple scattering properties of the medium. This work aims to demonstrate experimentally how the mixing effect influences the polarization phase curve at small phase angles for different mineralogies relevant for asteroids, and to determine how different aggregate sizes affect the negative polarization. We prepared a set of binary and ternary mixtures with different common minerals on asteroids and one set of the same mixture with different aggregate sizes. We measured their reflected light at 530 nm with full Stokes polarimetry at phase angles ranging from 0.8° to 30°. The mixing effect of the mixtures with both bright and dark minerals significantly changes the behavior of the phase curves in terms of minimum polarization, phase angle of the minimum, and inversion angle with respect to the mineral components that are mixed together. The changes in phase curve could explain the polarization observation of particular classes of asteroids (F and L class) and other asteroids with peculiar polarization curves or photometric properties. Furthermore, we demonstrate that the negative polarization is invariant to the presence of dust aggregates up to centimeter sizes.

T. J. Dunai, S. A. Binnie, A. Gerdes

<p>Analysis of cosmogenic nuclides produced in surface rocks and sediments is a valuable tool for assessing the rates of processes and the timing of events that shaped the Earth surface. The various nuclides that are used have specific advantages and limitations that depend on the time range over which they are useful, the type of material they are produced in and not least the feasibility of the analytical effort. Anticipating novel applications in Earth surface sciences, we develop in situ-produced terrestrial cosmogenic krypton (Kr<span class="inline-formula">_it</span>) as a new tool, the motivation being the availability of six stable and one radioactive isotope (<span class="inline-formula">⁸¹</span>Kr, half-life 229 kyr) and of an extremely weathering-resistant target mineral (zircon). We provide proof of principle that terrestrial Kr<span class="inline-formula">_it</span> can be quantified and used to unravel Earth surface processes.</p>

Chang-woo Cho, Cheuk Yin Ng, Chi Ho Wong et al.

We compare the upper critical field of bulk single-crystalline samples of the two intrinsic transition metal dichalcogenide superconductors, 2H-NbSe _2 and 2H-NbS _2 , in high magnetic fields where their layer structure is aligned strictly parallel and perpendicular to the field, using magnetic torque experiments and a high-precision piezo-rotary positioner. While both superconductors show that orbital effects still have a significant impact when the layer structure is aligned parallel to the field, the upper critical field of NbS _2 rises above the Pauli limiting field and forms a Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state, while orbital effects suppress superconductivity in NbSe _2 just below the Pauli limit, which excludes the formation of the FFLO state. From the out-of-plane anisotropies, the coherence length perpendicular to the layers of 31 Å in NbSe _2 is much larger than the interlayer distance, leading to a significant orbital effect suppressing superconductivity before the Pauli limit is reached, in contrast to the more 2D NbS _2 .

Pia Lois-Morales, Catherine Evans, Dion Weatherley

The characterisation technologies have advanced rapidly in the last decade. From a qualitative observation of minerals with optical microscopy, more quantitative techniques have emerged. Examples are the SEM-based technologies that focus on mineralogical identification at the microscale and the X-ray microtomography systems that allow identifying rock features in three dimensions.Features such as rock texture and mineralogy have a degree of control on how the rock behaves in the processing plant and thus can affect the project's economic feasibility. None of the available measurement devices is currently capable of identifying all the aspects of rock characteristics that are of interest in linking mineralogy and texture to process response in a single measurement. However, through the integrated use of the techniques in a complementary approach is possible to generate the required suite of information about the mineralogical composition and mineral grain size and shape in a given sample. A multisource method for rock characterisation has been developed in this work. This method includes:• A multistage imaging process that uses 2D and 3D microscopes• An object-segmentation technique to separate mineral grains in the photomicrographs for the quantification of mineralogical and textural properties.• A segmentation technique was developed to create particles of different sizes from a larger image.

Elena N. Yadrenkina, Svetlana B. Bortnikova, Nataliya V. Yurkevich et al.

This article provides the results of the elemental composition study of <i>Carassius auratus</i> organs living in the Komsomolsk mine tailings pond, in which the water contains elevated concentrations of metals and metalloids. It was determined with an electrotomography survey that the pond is bordered vertically and laterally with highly conductive zones, in which pore waters are high-mineralized solutions. Due to the constant infiltration of solutions into the pond water, a stable composition is formed with elevated concentrations of a number of elements (sulfate-ion, As, Sb, Zn, Cd, Se, and others) exceeding background values. In the organs of <i>Carassius auratus</i> living in the pond, the accumulation of many elements occurs, the largest Sb, As, Cd, Hg, and Pb and to a lesser extent Al, Cu, Zn, and Se. Moreover, the concentration of elements is selective. In total, the greatest excess of element concentrations over background values was determined in the heart (15,000 times) and gills (4100 times) of fish, the smallest in muscles (1900 times) and liver (2000 times). The impact of the accumulation of metals and metalloids in fish organs influenced the metabolic rate, a decrease in the growth rate of <i>Carassius auratus</i>, and the appearance of dwarf forms.

Marco Veneranda, Guillermo Lopez-Reyes, Elena Pascual Sanchez et al.

We evaluate what will be the effectiveness of the ExoMars Raman Laser Spectrometer (RLS) to determine the degree of serpentinization of olivine-rich units on Mars. We selected terrestrial analogues of martian ultramafic rocks from the Leka Ophiolite Complex (LOC) and analyzed them with both laboratory and flight-like analytical instruments. We first studied the mineralogical composition of the samples (mostly olivine and serpentine) with state-of-the-art diffractometric and spectroscopic laboratory systems. We compared these results with those obtained using our RLS ExoMars Simulator. Our work shows that the RLS ExoMars Simulator successfully identified all major phases. Moreover, when emulating the automatic operating mode of the flight instrument, the RLS ExoMars simulator also detected several minor compounds, some of which were not observed by NIR and XRD. Thereafter, we produced RLS dedicated calibration curves (R2 between 0.9993 and 0.9995 with an uncertainty between 3.0% and 5.2% with a confidence interval of 95%) to estimate the relative content of olivine and serpentine in the samples. Our results show that RLS can be very effective to identify serpentine, a scientific target of primary importance for the potential detection of biosignatures on Mars the main objective of the ExoMars rover mission.

Marco Veneranda, Jesus Saiz, Aurelio Sanz-Arranz et al.

The multi analytical study of terrestrial analogues is a useful strategy to deepen the knowledge about the geological and environmental evolution of Mars and other extraterrestrial bodies. In spite of the increasing importance that LIBS, NIR and Raman techniques are acquiring in the field of space exploration, there is a lack web-based platform providing free access to a wide multi-spectral database of terrestrial analogue materials. The Planetary Terrestrial Analogue Library (PTAL) project aims at responding to this critical need by developing and providing free web accessibility to LIBS, NIR and Raman data from more than 94 terrestrial analogues selected according to their congruence with Martian geological contexts. In this framework, the present manuscript provides the scientific community with a complete overview of the over 4500 Raman spectra collected to feed the PTAL database. Raman data, obtained through the complementary use of laboratory and spacecraft-simulator systems, confirmed the effectiveness of this spectroscopic technique for the detection of major and minor mineralogical phases of the samples, the latter being of critical importance for the recognition of geological processes that could have occurred on Mars and other planets. In light of the forthcoming missions to Mars, the results obtained through the RLS ExoMars Simulator offer a valuable insight on the scientific outcome that could derive from the RLS spectrometer that will soon land on Mars as part of the ExoMars rover payload.