{"results":[{"id":"doaj_10.1109/ACCESS.2026.3672109","title":"Raman Spectroscopy Pre-Trained Encoder: A Self-Supervised Learning Approach for Data-Efficient Domain-Independent Spectroscopy Analysis","authors":[{"name":"Abhiraam Eranti"},{"name":"Yogesh Tewari"},{"name":"Rafael Palacios"},{"name":"Amar Gupta"}],"abstract":"Deep-learning methods have boosted the analytical power of Raman spectroscopy, yet they still require large, task-specific, labeled datasets and often fail to transfer across application domains. The study explores pre-trained encoders as a solution. Pre-trained encoders have significantly impacted Natural Language Processing and Computer Vision with their ability to learn transferable representations that can be applied to a variety of datasets, significantly reducing the amount of time and data required to create capable models. The following work puts forward a new approach that applies these benefits to Raman Spectroscopy. The proposed approach, RSPTE (Raman Spectroscopy Pre-Trained Encoder), is designed to learn generalizable spectral representations without labels. RSPTE employs a novel domain adaptation strategy using unsupervised Barlow Twins decorrelation objectives to learn fundamental spectral patterns from multi-domain Raman Spectroscopy datasets containing samples from medicine, biology, and mineralogy. Transferability is demonstrated through evaluation on several models created by fine-tuning RSPTE for different application domains: Medicine (detection of Melanoma and COVID), Biology (Pathogen Identification), and Agriculture. As an example, using only 20% of the dataset, models trained with RSPTE achieve accuracies ranging 50%\u0026#x2013;86% (depending on the dataset used) while without RSPTE the range is 9%\u0026#x2013;57%. Using the full dataset, accuracies with RSPTE range 81%\u0026#x2013;97%, and without pre-training 51%\u0026#x2013;97%. Current methods and state-of-the-art models in Raman Spectroscopy are compared to RSPTE for context, and RSPTE exhibits competitive results, especially with less data as well. These results provide evidence that the proposed RSPTE model can effectively learn and transfer generalizable spectral features across different domains, achieving accurate results with less data in less time (both data collection time and training time).","source":"DOAJ","year":2026,"language":"","subjects":["Electrical engineering. Electronics. Nuclear engineering"],"doi":"10.1109/ACCESS.2026.3672109","url":"https://ieeexplore.ieee.org/document/11426888/","is_open_access":true,"published_at":"","score":70},{"id":"doaj_10.19111/bulletinofmre.1819341","title":"Importance of grain size distribution in quantitative analysis using Rietveld Method: An experimental study","authors":[{"name":"Arif Talay"},{"name":"Cumhur Özcan Kiliç"}],"abstract":"The Rietveld method refines a theoretical line profile until it fits the measured profile using a least squares methodology. In Rietveld method, complete qualitative mineral determination, mineralchemistry, appropriate XRD analytical conditions and sample preparation steps should be applied correctly. This study aims to determine the grain size-dependent variations in the quantitativecompositions of minerals with various chemical compositions and crystallographic characteristics. Eight pure minerals (quartz, calcite, halite, colemanite, barite, polyhalite, gypsum, thenardite) are been selected, powdered, pulverized and separated into 3 different grain sizes as 228μm (Dv90), 29μm (Dv90) and 8μm (Dv90). These minerals are mixed in certain proportions to prepare three mixture samples. Mixture samples are evaluated using the Rietveld Method on XRD whole rock patterns and then compared to the actual reference mixture sample whose mixing ratio is known for each grain size. Sample with a grain size of 8μm (Dv90) with random orientation gave the closest result compared to the reference content. If the structural and physical refinement stages are processed properly, accuracy of percentage mineralogical composition increases when the grain size decreases.","source":"DOAJ","year":2025,"language":"","subjects":["Mineralogy"],"doi":"10.19111/bulletinofmre.1819341","url":"https://dergipark.org.tr/tr/download/article-file/5400703","pdf_url":"https://dergipark.org.tr/tr/download/article-file/5400703","is_open_access":true,"published_at":"","score":69},{"id":"arxiv_2507.16777","title":"Silicate mineralogy and bulk composition of exoplanetary material in polluted white dwarfs","authors":[{"name":"Laura K. Rogers"},{"name":"Amy Bonsor"},{"name":"Érika Le Bourdais"},{"name":"Siyi Xu"},{"name":"Kate Y. L. Su"},{"name":"Benjamin Richards"},{"name":"Andrew Buchan"},{"name":"Nicholas P. Ballering"},{"name":"Marc Brouwers"},{"name":"Patrick Dufour"},{"name":"Markus Kissler-Patig"},{"name":"Carl Melis"},{"name":"Ben Zuckerman"}],"abstract":"White dwarf planetary systems uniquely link the bulk elemental composition of exoplanetary material to the mineralogy as photospheric abundances can be compared to circumstellar dust mineralogy. This study re-examines Spitzer/IRS spectra of eight white dwarfs with both circumstellar dust and photospheric metals. All systems show 10$μ$m silicate emission features consistent with a mixture of olivine and pyroxene silicates, with varying dominance. New Hubble Space Telescope ultraviolet spectroscopic observations of two of these systems, GD56 and WD1150-153, reveal that both are accreting dry, rocky material. WD1150-153 is accreting material consistent with Bulk Earth, while GD56 is accreting core-rich material with an inferred core mass fraction of 0.59$^{+0.08}_{-0.09}$ (0.37$^{+0.08}_{-0.08}$ by mole). A comparison between the bulk elemental composition of the accreted planetary material and the dust mineralogy of the eight systems reveals a tentative correlation between the dominant silicate mineralogy and the Mg/Si ratio, indicating that the circumstellar and photospheric material are compositionally similar. This suggests that rapid and well-mixed accretion is occurring with minimal compositional alteration. Furthermore, new GGCHEM equilibrium chemistry models confirm that Mg-rich planetary material preferentially forms olivine-rich dust, highlighting the importance of equilibrium in planetary chemistry and that a host star or rock's Mg/Si can be used to predict whether its silicate mineralogy is olivine- or pyroxene-dominated, influencing its capacity to structurally store water, recycle key nutrients, and possibly habitability.","source":"arXiv","year":2025,"language":"en","subjects":["astro-ph.EP","astro-ph.SR"],"url":"https://arxiv.org/abs/2507.16777","pdf_url":"https://arxiv.org/pdf/2507.16777","is_open_access":true,"published_at":"2025-07-22T17:23:36Z","score":69},{"id":"doaj_10.1038/s42003-024-06534-6","title":"Unraveling the pathological biomineralization of monosodium urate crystals in gout patients","authors":[{"name":"Carlos Rodriguez-Navarro"},{"name":"Kerstin Elert"},{"name":"Aurelia Ibañez-Velasco"},{"name":"Luis Monasterio-Guillot"},{"name":"Mariano Andres"},{"name":"Francisca Sivera"},{"name":"Eliseo Pascual"},{"name":"Encarnación Ruiz-Agudo"}],"abstract":"Abstract Crystallization of monosodium urate monohydrate (MSU) leads to painful gouty arthritis. Despite extensive research it is still unknown how this pathological biomineralization occurs, which hampers its prevention. Here we show how inflammatory MSU crystals form after a non-inflammatory amorphous precursor (AMSU) that nucleates heterogeneously on collagen fibrils from damaged articular cartilage of gout patients. This non-classical crystallization route imprints a nanogranular structure to biogenic acicular MSU crystals, which have smaller unit cell volume, lower microstrain, and higher crystallinity than synthetic MSU. These distinctive biosignatures are consistent with the template-promoted crystallization of biotic MSU crystals after AMSU at low supersaturation, and their slow growth over long periods of time (possibly years) in hyperuricemic gout patients. Our results help to better understand gout pathophysiology, underline the role of cartilage damage in promoting MSU crystallization, and suggest that there is a time-window to treat potential gouty patients before a critical amount of MSU has slowly formed as to trigger a gout flare.","source":"DOAJ","year":2024,"language":"","subjects":["Biology (General)"],"doi":"10.1038/s42003-024-06534-6","url":"https://doi.org/10.1038/s42003-024-06534-6","is_open_access":true,"published_at":"","score":68},{"id":"arxiv_2404.15426","title":"Exoplanet Mineralogy","authors":[{"name":"Keith D. Putirka"}],"abstract":"This chapter begins with some basic concepts regarding the structure and mineralogy of rocky planets, how to read and construct ternary diagrams, and why partial melting occurs when plate tectonics is operative. Partial melting is a key concept in that it governs crust and core formation, which in turn control mineralogy. These sections are for astronomers, or geologists new to the study of igneous petrology. From there, computational approaches for estimating planetary mineral assemblages will be introduced. These quantitative methods are simple, consonant with the level of information currently available on exoplanet compositions, and while largely intended for mineralogists, should be accessible to non-specialists as well. Such methods are followed by a study of error when plotting mineral abundances in ternary diagrams, for mineralogists and petrologists who construct such diagrams. The chapter concludes with caveats, and the ways in which exoplanets might surprise us.","source":"arXiv","year":2024,"language":"en","subjects":["astro-ph.EP","astro-ph.SR","physics.geo-ph"],"url":"https://arxiv.org/abs/2404.15426","pdf_url":"https://arxiv.org/pdf/2404.15426","is_open_access":true,"published_at":"2024-04-23T18:19:03Z","score":68},{"id":"arxiv_2405.11061","title":"The Empirical and Radiative Transfer Hybrid (EaRTH) Disk Model: Merging Analyses of Protoplanetary Dust Disk Mineralogy and Structure","authors":[{"name":"William Grimble"},{"name":"Joel Kastner"},{"name":"Christophe Pinte"},{"name":"Beth Sargent"},{"name":"David A. Principe"},{"name":"Annie Dickson-Vandervelde"},{"name":"Aurora Belen Aguayo"},{"name":"Claudio Caceres"},{"name":"Matthias R. Schreiber"},{"name":"Keivan G. Stassun"}],"abstract":"Our understanding of how exoplanets form and evolve relies on analyses of both the mineralogy of protoplanetary disks and their detailed structures; however, these key complementary aspects of disks are usually studied separately. We present initial results from a hybrid model that combines the empirical characterization of the mineralogy of a disk, as determined from its mid-infrared spectral features, with the MCFOST radiative transfer disk model, a combination we call the EaRTH Disk Model. With the results of the mineralogy detection serving as input to the radiative transfer model, we generate mid-infrared spectral energy distributions (SEDs) that reflect both the mineralogical and structural parameters of the corresponding disk. Initial fits of the SED output by the resulting integrated model to Spitzer Space T elescope mid-infrared (IRS) spectra of the protoplanetary disk orbiting the nearby T Tauri star MP Mus demonstrate the potential advantages of this approach by revealing details like the dominance of micron-sized olivine and micron-sized forsterite in this dusty disk. The simultaneous insight into disk composition and structure provided by the EaRTH Disk methodology should be directly applicable to the interpretation of mid-infrared spectra of protoplanetary disks that will be produced by the James Webb Space Telescope.","source":"arXiv","year":2024,"language":"en","subjects":["astro-ph.EP","astro-ph.SR"],"url":"https://arxiv.org/abs/2405.11061","pdf_url":"https://arxiv.org/pdf/2405.11061","is_open_access":true,"published_at":"2024-05-17T19:28:44Z","score":68},{"id":"doaj_10.5194/adgeo-59-59-2023","title":"Sources of Contaminants of Emerging Concern in Groundwater of Barcelona Urban Area","authors":[{"name":"D. Schmidlin"},{"name":"L. Scheiber"},{"name":"M. Teixidó"},{"name":"E. Vázquez"},{"name":"R. Criollo"},{"name":"A. Jurado"},{"name":"D. Puigserver"},{"name":"S. Burdons"},{"name":"M. Enrich"}],"abstract":"\u003cp\u003eGroundwater is a vital resource for the development of\nurban areas, where the problem focuses on the quantity and on the quality of\nthis freshwater resource. Barcelona is a good example as because currently\ngroundwater is used for irrigation of parks and gardens and street cleaning\ndue to its poor quality as drinking water source. Among the pollutants found\nin groundwater, of special interest are contaminants of emerging concern\n(CEC), as they pose a high risk to the aquatic environment and human health.\nThe behaviour, spatial distribution and processes that control them in the\naquatic environment are still uncertain and most of them are unregulated. In\nthis paper we study the inputs and processes controlling the hydrochemistry\nof Barcelona urban groundwater with special emphasis on the CEC. We selected\n29 CEC that were detected at high concentrations of up to 1 \u003cspan class=\"inline-formula\"\u003eµ\u003c/span\u003eg L\u003cspan class=\"inline-formula\"\u003e\u003csup\u003e−1\u003c/sup\u003e\u003c/span\u003e  (e.g.\ngemfibrozil, benzotriazole, among others). Towards the higher zones we\nidentify groundwater with relative low mineralization more proximate to the\nnatural recharge composition, while towards the urban area the anthropic\ninputs are evident (e.g. nitrate concentrations range from 50 to 200 mg L\u003cspan class=\"inline-formula\"\u003e\u003csup\u003e−1\u003c/sup\u003e\u003c/span\u003e).\nNear the Besòs river there is a clear contribution from this superficial\nwater highly polluted, mostly from wastewater treatment plant (WWTP)\ndischarges, and reducing conditions. The main contributor of CEC pollution\nin groundwater was the river-aquifer interaction (Besòs river), while\ntowards the urban area it might come from sewage seepage and probably a\nminor input from urban runoff. The redox state of these waters seems to\ncontrol the fate and occurrence of several of these CEC. The limitations of\nthis study are restricted to a single sampling campaign, therefore these\nresults should be corroborated with other sampling campaigns, including the\nseasonal variations, which would allow establishing more robust conclusions.\u003c/p\u003e","source":"DOAJ","year":2023,"language":"","subjects":["Science","Geology","Dynamic and structural geology"],"doi":"10.5194/adgeo-59-59-2023","url":"https://adgeo.copernicus.org/articles/59/59/2023/adgeo-59-59-2023.pdf","is_open_access":true,"published_at":"","score":67},{"id":"doaj_10.3390/geosciences13040114","title":"Rock Magnetism and Magnetic Fabric Study of the Icelandite and Rhyodacite Long Volcanic Sequence at Mauna Kuwale, Wai’anae Volcano, Oahu, Hawaii, USA","authors":[{"name":"Emilio Herrero-Bervera"},{"name":"Mario Moreira"}],"abstract":"In order to understand further the emplacement (i.e., volcanic growth) of 22 Icelandite and 3 Rhyodacite cooling units in one of the long volcanic sequences known as Mauna Kuwale of the Wai’anae volcano (ca. 3.3 Ma), Oahu Hawaii we have conducted appropriate rock magnetic experiments described below as well as anisotropy of magnetic susceptibility (AMS) studies of such 25 units. We have undertaken rock magnetic investigations such as continuous and partial thermo-magnetic cycles of low field magnetic susceptibility versus temperature dependence, (k-T) curves experiments. We classified the k-T heating-cooling dependence of susceptibility in three groups A, B and C. Type A: yielded two components of titano-magnetite with a predominat Ti rich phase and occasionally a relevant magnetite component phase. Type B: samples are characterized by Ti poor magnetites. Magnetite dominates as the main magnetic carrier. Type C: k-T curves show one single phase of titanomagnetite, and Ti poor magnetite. The coercivity or remanence, determined by back field magnetization is always \u003c60 mT, which suggest the predominance of magnetic components of low coercivity, like magnetite. Usually, two coercivity components are identified in the specimens. In addition we also conducted magnetic granulometry analyses on 27 specimens to determine the domain state of the flows. The ratio of hysteresis parameters (Mr/Mrs versus Hcr/Hc) show that overall samples fall in the Pseudo-Single Domain (PSD) region with high values of Mr/Mrs and very low values of Hcr/Hc. Only two samples from cooling units 17 and specially 22 show a Single Domain (SD) magnetic behavior and a sample from one unit approaches the SD-MD mixture region. We measured the magnetic susceptibility of all cooling units and we found out that in all analyzed units the magnetic susceptibility is low 13.7 ± 8.8 (10\u003csup\u003e−3\u003c/sup\u003e SI). Magnetic anisotropy/magnetic fabric is used as a tool in rock fabric analyses to investigate the preferred orientation of magnetic minerals in rocks. Magnetic anisotropy is low on all (measured) flows from the Icelandite cooling units from 1 to 17 (mean P’ = 1.010), but becomes noticeably distinct and high in rhyodacite cooling units 23, 24 and 25 (mean P’ = 1.074). Four units show a magnetic fabric with k\u003csub\u003e3\u003c/sub\u003e axes vertical to sub-vertical which may be denoted as normal for the horizontal to sub horizontal units. Two Icelandite cooling units display oblate shapes and two other cooling units triaxial shapes. K\u003csub\u003e1\u003c/sub\u003e axes are horizontal but point in different directions, i.e., NE and NW. Remaining cooling units show different magnetic fabric. Units 17, 23, 24 and 25, despite important variations in anisotropy (low for units 25 and high for units 23 and 24) and shape of ellipsoid (oblate in cooling unit 23, prolate in 24 and triaxial in 25) the k\u003csub\u003e3\u003c/sub\u003e axes show the same orientation, SW to SSW dipping around 45° and a very steady magnetic lineation azimuth NW nearly horizontal to sub horizontal. The magnetic mineralogy and magnetic fabric indicate that both the Icelandite and Rhyodacite cooling units the magmatic evolution during the shield stage of the entire Wai’anae volcano and that such growth was not affected by tectonic deformation.","source":"DOAJ","year":2023,"language":"","subjects":["Geology"],"doi":"10.3390/geosciences13040114","url":"https://www.mdpi.com/2076-3263/13/4/114","is_open_access":true,"published_at":"","score":67},{"id":"doaj_10.1016/j.cscm.2023.e02642","title":"Antimicrobial geopolymer paints based on modified natural zeolite","authors":[{"name":"Aleksandar Nikolov"},{"name":"Lili Dobreva"},{"name":"Svetla Danova"},{"name":"Jeny Miteva-Staleva"},{"name":"Ekaterina Krumova"},{"name":"Viktor Rashev"},{"name":"Neli Vilhelmova-Ilieva"},{"name":"Liliya Tsvetanova"},{"name":"Borislav Barbov"}],"abstract":"Many antimicrobial coatings deliver a peak release of antimicrobial agent at an early age, after which they lost antimicrobial activity over time. In the present study a novel geopolymer paints with long term antimicrobial activity were developed based on natural zeolite modified with silver and copper ions. The obtained geopolymer paints were applied by brushing on concrete, ceramic, gypsum paperboard and steel. The coating was characterized by excellent adhesive strength and hiding properties. The long-term antimicrobial effect was evaluated by accelerated aging in carbonation chamber. Microstructural changes were analyzed by powder X-ray diffraction and Fourier transformed infrared spectroscopy. Cytotoxicity, antibacterial, antifungal and virucidal properties were investigated on raw and carbonated geopolymer paints. Geopolymer paints based on modified natural zeolite seems promising antimicrobial coating material that can be implemented in the global fight against the spread of diseases and pathogens.","source":"DOAJ","year":2023,"language":"","subjects":["Materials of engineering and construction. Mechanics of materials"],"doi":"10.1016/j.cscm.2023.e02642","url":"http://www.sciencedirect.com/science/article/pii/S2214509523008227","is_open_access":true,"published_at":"","score":67},{"id":"arxiv_2308.09505","title":"A mineralogical reason why all exoplanets cannot be equally oxidising","authors":[{"name":"Claire Marie Guimond"},{"name":"Oliver Shorttle"},{"name":"Sean Jordan"},{"name":"John F. Rudge"}],"abstract":"From core to atmosphere, the oxidation states of elements in a planet shape its character. Oxygen fugacity (fO$_2$) is one parameter indicating these likely oxidation states. The ongoing search for atmospheres on rocky exoplanets benefits from understanding the plausible variety of their compositions, which depends strongly on their oxidation states -- and if derived from interior outgassing, on the fO$_2$ at the top of their silicate mantles. This fO$_2$ must vary across compositionally-diverse exoplanets, but for a given planet its value is unconstrained insofar as it depends on how iron (the dominant multivalent element) is partitioned between its 2+ and 3+ oxidation states. Here we focus on another factor influencing how oxidising a mantle is -- a factor modulating fO$_2$ even at fixed Fe$^{3+}$/Fe$^{2+}$ -- the planet's mineralogy. Only certain minerals (e.g., pyroxenes) incorporate Fe$^{3+}$. Having such minerals in smaller mantle proportions concentrates Fe$^{3+}$, increasing fO$_2$. Mineral proportions change within planets according to pressure, and between planets according to bulk composition. Constrained by observed host star refractory abundances, we calculate a minimum fO$_2$ variability across exoplanet mantles, of at least two orders of magnitude, due to mineralogy alone. This variability is enough to alter by a hundredfold the mixing ratio of SO$_2$ directly outgassed from these mantles. We further predict that planets orbiting high-Mg/Si stars are more likely to outgas detectable amounts of SO$_2$ and H$_2$O; and for low-Mg/Si stars, detectable CH$_4$, all else equal. Even absent predictions of Fe$^{3+}$ budgets, general insights can be obtained into how oxidising an exoplanet's mantle is.","source":"arXiv","year":2023,"language":"en","subjects":["astro-ph.EP"],"doi":"10.1093/mnras/stad2486","url":"https://arxiv.org/abs/2308.09505","pdf_url":"https://arxiv.org/pdf/2308.09505","is_open_access":true,"published_at":"2023-08-18T12:30:03Z","score":67},{"id":"doaj_10.1029/2021GC009730","title":"Internal Water Facilitates Thermal Resetting of Clumped Isotopes in Biogenic Aragonite","authors":[{"name":"C. W. Nooitgedacht"},{"name":"H. J. L. van der Lubbe"},{"name":"M. Ziegler"},{"name":"P. T. Staudigel"}],"abstract":"Abstract Biogenic and inorganic calcium carbonates contain considerable amounts of internal water, both as free and organically associated water. The oxygen isotopic compositions (δ18O) of internal water and hosting carbonate are analyzed for various carbonates before and after heating at 175°C for 90 minutes. During heating, the δ18O values of internal water significantly increased in biogenic aragonites and speleothem calcite, whereas the δ18O carbonate values were lowered. Correspondingly, an aragonitic bivalve’s clumped‐isotope distribution (Δ47) changed during heating, increasing reconstructed paleotemperatures. In contrast, an inorganic aragonite crystal, containing a comparable amount of internal water, showed no oxygen isotope exchange, and its Δ47 values remained unaltered during heating, implying that there is a link between internal oxygen isotope exchange and Δ47 resetting. This alteration process occurred without any detectable transformation from aragonite to calcite. Our results therefore reveal a mechanism that facilitates oxygen isotope exchange between biogenic aragonite and its internal water, while simultaneously resetting the Δ47 values, without affecting mineralogy. Future studies may therefore apply coupled water‐carbonate analyses to scrutinize these kinds of diagenetic alteration processes. It appears that in biogenic aragonites, more carbonate is available for exchange reactions with the internal water reservoir than in inorganic aragonites, a feature that can be attributed to the distribution of organic‐associated water and/or high surface area fluid inclusions. This water‐aragonite exchange occurs at lower temperatures than those required for solid‐state bond reordering at the same timescale, and thus likely has occurred earlier during the burial of biogenic aragonites.","source":"DOAJ","year":2021,"language":"","subjects":["Geophysics. Cosmic physics","Geology"],"doi":"10.1029/2021GC009730","url":"https://doi.org/10.1029/2021GC009730","is_open_access":true,"published_at":"","score":65},{"id":"arxiv_2102.07634","title":"Thermal alteration of CM carbonaceous chondrites: mineralogical changes and metamorphic temperatures","authors":[{"name":"Ashley J. King"},{"name":"Paul F. Schofield"},{"name":"Sara S. Russell"}],"abstract":"The CM carbonaceous chondrite meteorites provide a record of low temperature aqueous reactions in the early solar system. A number of CM chondrites also experienced short-lived, post-hydration thermal metamorphism at temperatures of 200C to over 750C. The exact conditions of thermal metamorphism and the relationship between the unheated and heated CM chondrites are not well constrained but are crucial to understanding the formation and evolution of hydrous asteroids. Here we have used position-sensitive-detector X-ray diffraction (PSD-XRD), thermogravimetric analysis (TGA) and transmission infrared (IR) spectroscopy to characterise the mineralogy and water contents of 14 heated CM and ungrouped carbonaceous chondrites. We show that heated CM chondrites underwent the same degree of aqueous alteration as the unheated CMs, however upon thermal metamorphism their mineralogy initially (300 to 500C) changed from hydrated phyllosilicates to a dehydrated amorphous phyllosilicate phase. At higher temperatures (over 500C) we observe recrystallisation of olivine and Fe-sulphides and the formation of metal. Thermal metamorphism also caused the water contents of heated CM chondrites to decrease from 13 wt percent to 3 wt percent and a subsequent reduction in the intensity of the 3 micron feature in IR spectra. We estimate that the heated CM chondrites have lost 15 to 65 percent of the water they contained at the end of aqueous alteration. If impacts were the main cause of metamorphism, this is consistent with shock pressures of 20 to 50 GPa. However, not all heated CM chondrites retain shock features suggesting that some were instead heated by solar radiation. Evidence from the Hayabusa2 and ORSIRS-REx missions suggest that dehydrated materials may be common on the surfaces of primitive asteroids and our results will support upcoming analysis of samples returned from asteroids Ryugu and Bennu.","source":"arXiv","year":2021,"language":"en","subjects":["astro-ph.EP","physics.geo-ph"],"doi":"10.1016/j.gca.2021.02.011","url":"https://arxiv.org/abs/2102.07634","pdf_url":"https://arxiv.org/pdf/2102.07634","is_open_access":true,"published_at":"2021-02-15T16:15:42Z","score":65},{"id":"doaj_10.30479/jmre.2020.10200.1237","title":"برآورد احتمالاتی توزیع بار در واحدهای فرآوری مواد معدنی با روش زنجیره مارکف","authors":[{"name":"مهدی نوروزی"},{"name":"سید محمد اسماعیل جلالی"},{"name":"اصغر عزیزی"}],"abstract":"در روش‌های مرسوم موازنه جرم، برای تعیین عیار فلز، درصد جامد و توزیع دانه\u003cem\u003e‌\u003c/em\u003eبندی نمونه‌برداری در مسیرها (شاخه\u003cem\u003e‌\u003c/em\u003eها) انجام می\u003cem\u003e‌\u003c/em\u003eشود و در نهایت خطاهای مربوط به آنها سرشکن می\u003cem\u003e‌\u003c/em\u003eشود. در این روش\u003cem\u003e‌\u003c/em\u003eها، برای هر واحد فرآوری (تجهیزات کارخانه)، در خصوص مقدار بار و عیار یا محتوای فلز اطلاعات لحظه‌ای وجود ندارد. در این مقاله با بهره‌گیری از نظریه فرآیند‌های تصادفی، مقادیر کمی و کیفی بار ورودی به هر یک از واحدهای عملیاتی در مسیر فرآوری به شکل احتمالات در نظر گرفته و توزیع بار در واحدهای مذکور برآورد شده است. به این منظور، ابتدا کارخانه فرآوری به صورت یک گراف جهت‌دار و موزون مدل‌سازی شده است. در این گراف، هرگره بیانگر یک واحد عملیاتی و هر یال، نشان‌دهنده مسیر واقع بین دو واحد است. وزن هر یال معرف وزن مواد عبوری در مسیر از گره‌ای به گره دیگر بوده و در یک بازه زمانی مشخص به‌عنوان یک متغیر تصادفی منظور شده است. پس از مدل‌سازی فرآیند، مدل گرافی به‌دست آمده که در برگیرنده شاخص‌های تصادفی است با استفاده از نظریه\"زنجیرهای مارکف\" تحلیل شده است. با روش ارایه شده در این مقاله نه تنها توزیع بار، بلکه احتمال حضور هر ذره یا کانی، در هر یک از واحدهای عملیاتی کارخانه فرآوری نیز قابل پیش‌بینی است. همچنین در صورت توقف کارخانه، می\u003cem\u003e‌\u003c/em\u003eتوان تناژ موجود در هر یک از واحدها را تخمین زد و اقدامات لازم برای تخلیه آنها را فراهم کرد. در این تحقیق، خط فرآوری سنگ آهن چادرملو با روش بالا، مدل‌سازی و نتایج حاصل تحلیل و سپس با استفاده از شاخص‌های احتمالات گزارش شده است.","source":"DOAJ","year":2020,"language":"","subjects":["Mineralogy"],"doi":"10.30479/jmre.2020.10200.1237","url":"http://jmre.journals.ikiu.ac.ir/article_2100_da9bc8bce07fedae582af1533bb73fd1.pdf","pdf_url":"http://jmre.journals.ikiu.ac.ir/article_2100_da9bc8bce07fedae582af1533bb73fd1.pdf","is_open_access":true,"published_at":"","score":64},{"id":"doaj_10.3390/app10207321","title":"Localisation of Ancient Migration Pathways inside a Fractured Metamorphic Hydrocarbon Reservoir in South-East Hungary","authors":[{"name":"Tivadar M. Tóth"},{"name":"László Molnár"},{"name":"Sándor Körmös"},{"name":"Nóra Czirbus"},{"name":"Félix Schubert"}],"abstract":"Numerous fractured hydrocarbon reservoirs exist in the metamorphic basement of the Pannonian Basin in Hungary. Many decades of experience in production have proven that these reservoirs are highly compartmentalised, resulting in a complex mosaic of permeable and impermeable domains situated next to each other. Consequently, in most fields, only a small amount of the total hydrocarbon reserve can be extracted. This paper aims to locate the potential migration pathways inside the most productive basement reservoir of the Pannonian Basin, using a multiscale approach. To achieve this, evaluation well-log data, DFN modelling and a composition analysis of fluid trapped in a vein-filling zeolite phase are combined. Data on a single well are presented as an example. The results of the three approaches indicate the presence of two highly fractured intervals separated by a barely fractured amphibolite. The two zones are probably part of the communicating fracture system inside the single metamorphic mass. The gas analysis further specifies the migrated fluids and indicates hydrocarbons of a composition similar to that of the recently produced oil. Consequently, we conclude that the two zones do not only form an ancient migration pathway but are also members of a more recent hydrocarbon system.","source":"DOAJ","year":2020,"language":"","subjects":["Technology","Engineering (General). Civil engineering (General)","Biology (General)","Physics","Chemistry"],"doi":"10.3390/app10207321","url":"https://www.mdpi.com/2076-3417/10/20/7321","is_open_access":true,"published_at":"","score":64},{"id":"arxiv_2007.01856","title":"$^{26}$Al-$^{26}$Mg isotopic, mineralogy, petrography of a Hibonite-Pyroxene Spherule in Allan Hills 77307 (CO3.03): Implications for the origin and evolution of these objects","authors":[{"name":"Ritesh Kumar Mishra"}],"abstract":"10 Hibonite-pyroxene/glass spherules discovered hitherto are a rare suite of refractory inclusions that show the largest range of exotic isotopic properties (anomalies in neutron rich isotopes (e.g., $^{48}$Ca, $^{50}$Ti), abundance of $^{26}$Al) despite their defining simple spherical morphology and mineralogy consisting predominantly of few hibonites nestled within/with glassy or crystallised calcium, aluminium-rich pyroxene. $^{26}$Al-$^{26}$Mg chronological studies along with petrography and mineralogy of a relatively large (~120 micron diameter), found in Allan Hills 77307 (CO3.03) has been performed. Uniquely, both hibonite and pyroxene show discordant abundance of short-lived now-extinct radionuclide $^{26}$Al that suggest disparate and distinct regions of origin of hibonite and pyroxene. The pristine petrography and mineralogy of this inclusion allow discernment of their genesis and trend of alteration in hibonite-pyroxene/glass spherules.","source":"arXiv","year":2020,"language":"en","subjects":["astro-ph.EP","astro-ph.SR"],"url":"https://arxiv.org/abs/2007.01856","pdf_url":"https://arxiv.org/pdf/2007.01856","is_open_access":true,"published_at":"2020-07-02T18:18:27Z","score":64},{"id":"doaj_10.1002/dep2.71","title":"Salinity, microbe and carbonate mineral relationships in brackish and hypersaline lake sediments: A case study from the tropical Pacific coral atoll of Kiritimati","authors":[{"name":"Susan Schmitt"},{"name":"Jessica L. Conroy"},{"name":"Theodore M. Flynn"},{"name":"Robert A. Sanford"},{"name":"Melinda C. Higley"},{"name":"Mingfei Chen"},{"name":"Bruce W. Fouke"}],"abstract":"Abstract Microbiological activity can exert a substantial influence on carbonate mineral precipitation, but linking specific microbiological processes to carbonate minerals in an environmental setting is complex, as both abiotic and biotic factors ultimately influence carbonate mineral precipitation. The coral atoll of Kiritimati, Republic of Kiribati (1.9°N, 157.4°W), in the central tropical Pacific Ocean, contains hundreds of shallow water brackish to hypersaline lakes that contain a range of carbonate and evaporite minerals. Previous studies of Kiritimati lakes have investigated the microbial communities of finely laminated microbial mats and associated microbialites found in several of the more hypersaline lakes on the island. However, the microbial communities of the more brackish lakes are unknown. These brackish lakes precipitate metres of fine‐grained carbonate muds, which are useful for palaeoenvironmental reconstruction. Here, the relationships between carbonate abundance, mineralogy, water chemistry, and bacterial and archaeal communities are investigated in a suite of brackish to hypersaline lakes (8.7‐190 ppt) on Kiritimati. Next generation 16S rRNA gene sequencing of bacteria and archaea indicate that brackish lake sediments contain distinct microbial communities. In relation to carbonate precipitation, the relative abundance of Cyanobacteria, Choloroflexi and Deltaproteobacteria is greater in the brackish lake sediments, suggesting photosynthesis and sulphate reduction associated with these taxa may strongly influence alkalinity and carbonate precipitation in brackish lakes. The presence of dolomite in certain hypersaline lakes also coincided with the presence of a methanogenic family, indicating that methogenesis may contribute to dolomite precipitation in these lakes.","source":"DOAJ","year":2019,"language":"","subjects":["Geology"],"doi":"10.1002/dep2.71","url":"https://doi.org/10.1002/dep2.71","is_open_access":true,"published_at":"","score":63},{"id":"arxiv_1905.11779","title":"Evaluation of mineralogy per geological layers by Approximate Bayesian Computation","authors":[{"name":"Vianney Bruned"},{"name":"Alice Cleynen"},{"name":"André Mas"},{"name":"Sylvain Wlodarczyck"}],"abstract":"We propose a new methodology to perform mineralogic inversion from wellbore logs based on a Bayesian linear regression model. Our method essentially relies on three steps. The first step makes use of Approximate Bayesian Computation (ABC) and selects from the Bayesian generator a set of candidates-volumes corresponding closely to the wellbore data responses. The second step gathers these candidates through a density-based clustering algorithm. A mineral scenario is assigned to each cluster through direct mineralogical inversion, and we provide a confidence estimate for each lithological hypothesis. The advantage of this approach is to explore all possible mineralogy hypotheses that match the wellbore data. This pipeline is tested on both synthetic and real datasets.","source":"arXiv","year":2019,"language":"en","subjects":["stat.AP","physics.geo-ph"],"url":"https://arxiv.org/abs/1905.11779","pdf_url":"https://arxiv.org/pdf/1905.11779","is_open_access":true,"published_at":"2019-05-28T12:48:51Z","score":63},{"id":"arxiv_1907.05506","title":"The Composition and Mineralogy of Rocky Exoplanets: A Survey of \u003e4,000 Stars from the Hypatia Catalog","authors":[{"name":"Keith D. Putirka"},{"name":"John C. Rarick"}],"abstract":"We present a survey of \u003e4,000 star compositions from the Hypatia Catalog to examine whether rocky exoplanets (i.e., those with rocky surfaces, dominated by silicates) might be geologically similar to Earth, at least with respect to composition and mineralogy. To do so, we explore the variety of reported stellar compositions to then determine a possible range of exoplanetary mantle mineralogies. We find that exoplanetary mantles will likely be dominated by olivine and/or orthopyroxene, depending upon Fe partitioning during core formation. Some exoplanets may be magnesiowustite- or quartz-saturated, and we present a new classification scheme based on the weight $\\%$ ratio (FeO+MgO)/SiO$_{2}$, to differentiate rock types. But wholly exotic mineralogies should be rare to absent. We find that half or more of the range of exoplanet mantle mineralogy is controlled by core formation, which we model using $α_{Fe}$ = $Fe^{BSP}$/$Fe^{BP}$, where $Fe^{BSP}$ is Fe in a Bulk Silicate Planet (bulk planet, minus core), on a cation weight $\\%$ basis (elemental weight proportions, absent anions) and $Fe^{BP}$ is the cation weight $\\%$ of Fe for a Bulk Planet. In our solar system, $α_{Fe}$ varies from 0 (Mercury) to about 0.54 (Mars). Remaining variations in exoplanet mantle mineralogy result from non-trivial variations in star compositions. Our major oxide analysis also verifies earlier, isotopic studies indicating that Earth is non-solar (non-chondritic). We also find that major oxide estimates for Earth's mantle appear to preclude a hidden component in the deep mantle that would allow for a bulk solar/chondritic Earth. If it did exist, such a hidden component must comprise at least 28% of the mass of the total mantle (to avoid negative concentrations of some oxides) and would not look anything like the sources of ocean island or mid-ocean ridge basalts.","source":"arXiv","year":2019,"language":"en","subjects":["astro-ph.EP"],"url":"https://arxiv.org/abs/1907.05506","pdf_url":"https://arxiv.org/pdf/1907.05506","is_open_access":true,"published_at":"2019-07-11T22:04:50Z","score":63},{"id":"arxiv_1904.11414","title":"Olivine-Carbonate Mineralogy of the Jezero Crater Region","authors":[{"name":"Adrian J. Brown"},{"name":"Christina E. Viviano"},{"name":"Timothy A. Goudge"}],"abstract":"A well-preserved, ancient delta deposit, in combination with ample exposures of carbonate rich materials, make Jezero Crater in Nili Fossae a compelling astrobiological site. We use Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) observations to characterize the surface mineralogy of the crater and surrounding watershed. Previous studies have documented the occurrence of olivine and carbonates in the Nili Fossae region. We focus on correlations between these two well studied lithologies in the Jezero crater watershed. We map the position and shape of the olivine 1 μm absorption band and find that carbonates are only found in association with olivine which displays a 1 μm band shifted to long wavelengths. We then use THEMIS coverage of Nili Fossae and perform tests to investigate whether the long wavelength shifted olivine signature is correlated with high thermal inertia outcrops. We find no correlation between thermal inertia and the unique olivine signature. We discuss a range of formation scenarios, including the possibility that these olivine and carbonate associations are products of serpentinization reactions on early Mars. These lithologies provide an opportunity for deepening our understanding of early Mars, and, given their antiquity, may provide a framework to study the formation of valley networks, and the thermal history of the martian crust and interior from the early Noachian to today.","source":"arXiv","year":2019,"language":"en","subjects":["astro-ph.EP"],"doi":"10.1029/2019JE006011","url":"https://arxiv.org/abs/1904.11414","pdf_url":"https://arxiv.org/pdf/1904.11414","is_open_access":true,"published_at":"2019-04-25T15:40:03Z","score":63},{"id":"doaj_10.22108/ijp.2019.114335.1110","title":"Mineralogy, geochemistry and fluid inclusion studies of Dagh-Dali Zn-Pb(±Au) Deposit, Northern Takab, Northwest Iran","authors":[{"name":"Yousef Rahimsouri"},{"name":"Behzad Mehrabi"},{"name":"Shirin Alipour"}],"abstract":"Dagh-Dali Zn-Pb deposit is located 40 km north of Takab city and it consist of Bekhair-Bolaghi and Baldirghani ore zones. Mineralization in Bekhair-Bolaghi is consist of galena, sphalerite, pyrite and chalcopyrite with disseminated texture hosted in the Kahar shales and Jangotaran dolomitized limestone. Sphalerite is mainly associated with galena or surrounded by pyrite. Galena is formed in two forms of disseminated and fine crystalline texture in association with chalcopyrite and massive texture in association with sphalerite. Stibnite is associated with galena and sphalerite, and chalcopyrite is the least frequent sulfide minerals in the deposit. Gold scan study shows a insignificant concentration of gold in pyrite structure. In Baldirghani, As-Sb-Au mineralization occurred in marl, sandstone and tuff of the Qom Formation. Realgar and orpiment with mosaic, stibnite with radial and spheroidal, barite with fibrous and sphalerite with spheroidal textures are hosted in quartz vein. There is trace of gold in realgar and stibnite structure based on gold scan study. Based on geochemical investigation in Bekhair-Bolaghi, Pb-Zn, Pb-Ag, Zn-Sb, Ag-Sb and Pb-Sb pairs and in Baldirghani, Pb-Zn and Pb-Ag pairs have strong positive correlation. Exploration drilling results indicate that mineralization is shallow(\u003c30m). Fluid inclusion analyses indicate that ore bearing fluid salinity is 4.55 to 6.81 wt% NaCl eq. with mean temperature 212.5°C for Bekhair-Bolaghi and 1.65 to 10.48 wt% NaCl eq. with temperatures 170 to 207°C for Baldirghani. Based on geological, mineralogical, geochemical and fluid inclusion studies, it seems that Dagh-Dali Zn-Pb deposit is similar to low sulfidation type deposits.","source":"DOAJ","year":2018,"language":"","subjects":["Petrology"],"doi":"10.22108/ijp.2019.114335.1110","url":"http://ijp.ui.ac.ir/article_23791_b48d9af5e7466bf0e528110ab22c8334.pdf","pdf_url":"http://ijp.ui.ac.ir/article_23791_b48d9af5e7466bf0e528110ab22c8334.pdf","is_open_access":true,"published_at":"","score":62}],"total":41370,"page":1,"page_size":20,"sources":["CrossRef","DOAJ","arXiv"],"query":"Mineralogy"}