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Spears, daggers, and axes with obsidian tips and blades made by inhabitants of the Admiralty Islands (Manus Province, Papua New Guinea) were intensively collected by Europeans during the later 19th and early 20th centuries and are widely represented in museum collections. Prior studies have shown how islanders creatively responded to increasing European demand by changing style and manufacturing strategies. What is less well understood is how the colonial encounter, particularly during its early stages, opened new opportunities for producers to work outside traditional patterns of ownership. Obsidian source assignments for a large sample of implements dated c. 1850–1990 show that as museum collecting intensified, the number of sources utilized expanded from a single source to multiple obsidian flows, indicating that customary production monopolies had broken down in response to opportunities for commercial trade. This case study demonstrates the valuable role that chemical characterization can play in studies of cross-cultural encounter and engagement. [ABSTRACT FROM AUTHOR]

Northwest Africa (NWA) 12384 is a lunar polymict breccia composed almost entirely of basaltic components. The clast content includes low‐ to very‐low‐Ti volcanic picritic glass, basaltic vitrophyre, and crystalline pigeonite basalt—an assemblage of volcanic materials that can be tested for petrogenetic relationships. We present the inferred history of select mare components of NWA 12384 as suggested by texture, mineralogy, and petrography, and compare them to Apollo samples and other lunar meteorites. In addition, we used the volcanic glasses in the breccia as a primary composition for crystallization modeling and comparison to the lithic clast compositions. We find that the mafic clasts in NWA 12384 cannot be derived from the picritic glass through a common liquid line of descent because of higher Ti content, though they may have crystallized from a separate, common liquid line of descent. These clasts could represent local source‐region heterogeneity or differential assimilation of more Ti‐rich material. Pb‐Pb SIMS analyses of a large basalt clast in NWA 12384 reveal an age of 3044 ± 41 Ma (2σ), which is used together with the chemical data and 4π cosmic ray exposure age of less than 20 kyr and terrestrial age of between 3.1 and 17.3 kyr to constrain the possible locations of provenance for this meteorite. [ABSTRACT FROM AUTHOR]

In western Asia, the Zagros foothills played a fundamental role in the formulation of early explanatory hypotheses on the origins of agriculture. The excavations at the emblematic Neolithic site of Ali Kosh, Deh Luran, led to the development of the so-called "marginal zone hypothesis." However, some chronological inconsistencies remained until a new stratigraphic excavation was carried out in 2017 to revise the findings. According to the new evaluation, Ali Kosh was occupied from ca. 7500–6500 cal b.c. During the Boz Mordeh phase (ca. 7500–7350 b.c.), the inhabitants occupied the site seasonally, but they became increasingly sedentary in the succeeding Ali Kosh phase (ca. 7350–7000 b.c.). In addition to obsidian, they also imported beads of stone and sea shell. Moreover, they increasingly relied on herding sheep and fully domesticated goats. The emergence of Neolithic life in the lowlands was a direct consequence of cultural changes in the central Zagros. It is not yet known whether this was a result of climatic deterioration or population pressure in the highlands. [ABSTRACT FROM AUTHOR]

The editorial discusses the changing eruptive behavior of volcanoes, transitioning between effusive and explosive eruptions, with examples from various locations like Pinatubo, Mount Saint Helens, and Popocatépetl. The causes of these mood swings are not fully understood, leading to challenges in forecasting eruption styles and magnitudes. The text highlights the importance of studying volcanic processes, magma composition, and monitoring parameters to better understand and mitigate volcanic hazards. Additionally, it emphasizes the need for further research to comprehend the impacts of these regime changes on the environment and climate change. [Extracted from the article]

The obsidian dating method converts the quantity of diffused molecular water within a near‐surface hydration layer to elapsed time using an experimentally derived diffusion coefficient predicted from the structural water content of the glass. Infrared spectroscopic transmission measurements on transparent archaeological samples record vibrational responses of water bands in the near‐infrared region, permitting determination of structural water content (OH), and the amount of diffused ambient water (H2O). In this application, the H2O water band at 5200 cm−1 is measured directly. The accuracy of the approach is assessed by an evaluation of the precision of each contributing variable. The new protocol is evaluated using obsidian artifacts from radiocarbon‐dated deposits at Salamanca Cave in Argentina. [ABSTRACT FROM AUTHOR]

Conclusion: We have identified the rhyolitic samples from the HT geothermal drillhole KT-8 in the Tianzhen area, northeastern Datong Basin. Such rock consists of phenocryst grain of quartz, perthite, and biotite with minor volcanic glass. The geothermometer of ternary-feldspar yields the crystallized temperatures ranging from 600 to 800 °C with average value of 700 °C, representing the crystallized temperature of rhyolitic magma. According to major and trace element characteristics as well as Sr-Nd isotope, such magma likely derived from partial melting of Archean gneissic complexes that was triggered by the segregation of mantle-derived basalts in the studying area. The magmatic evolution is important link between deeply magmatic source and shallow volcanic activity. Combined with tectonic background and geothermal investigation, the rhyolite and its surrounding gneissic complexes would be as the source and reservoir for the HT geothermal system in the Tianzhen area, respectively. The final publication is available at Springer via https://doi.org/10.1007/s12583-024-0035-y. [ABSTRACT FROM AUTHOR]

We have obtained the first data on the chemical composition of the eruptive materials from the explosive eruption of Bezymianny volcano on April 7, 2023. Our unique collection includes freshly sampled pumice lapilli from the eruption and juvenile blocks from pyroclastic flows. We have identified interesting patterns in both macro components and specific chalcophile elements, such as copper. The rocks we studied belong to medium-K two-pyroxene basaltic andesite (55.5‒57 wt % SiO2), with mafic enclaves characterized by a slightly more primitive composition (53.7 wt % SiO2). According to mineral geothermometry data, the phenocrysts of basaltic andesite crystallized at temperatures in the range from 940 to 960°C, while the formation of phenocryst rims and microlites occurred at 980°C, which corresponds to conditions immediately before the eruption. The composition of volcanic glass allows us to estimate the pressure at which the magma reached the last equilibrium with crystallizing phases before eruption (0.5‒0.6 kbar). Based on these findings, we have formulated hypotheses about the potential evolution of the shallow magma chamber of Bezymianny volcano during the period from 2017 to 2023. [ABSTRACT FROM AUTHOR]

Advancements in scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX) technologies have reached the point where rapid, fully quantitative, non-destructive and high-resolution acquisition of effectively all major element chemical information from polished sample material is possible. Here, we discuss optimisation parameters and demonstrate the data quality that can be achieved for SEM-EDX analysis of magmatic glass samples; glass represents a particular challenge due its lack of stoichiometry and potential for beam-induced element mobilisation. We test our approach through analysis of reference materials and demonstrate the advantages of SEM-EDX for several volcanic glasses that were previously investigated with electron probe micro-analysis (EPMA). SEM-EDX analysis is typically undertaken at a much lower beam current than EPMA, allowing for non-destructive analysis of geologic material that are sensitive to a higher beam current, such as sodium-rich glass. With careful instrument set-up, robust standardisation, and optimal experiment parameters, SEM-EDX analysis can achieve major and minor element data comparable with that collected via EPMA, with the exception of low abundance elements (those below 0.2 wt%). In addition, SEM-EDX analysis typically uses a smaller beam diameter and so permits analysis of smaller features than EPMA. Our results show that this technique can be potentially used as a quantitative tool on a wide range of geological materials with faster analysis, improved spatial resolution and cost advantages making it a complementary or alternative analytical method to EPMA. [ABSTRACT FROM AUTHOR]

Titanium (Ti), a typical rock-forming element, is traditionally considered to be lithophile, incompatible, and fluid-immobile, and is recognized as a significant proxy for understanding the oceanic environments, such as the content of terrestrial materials in modern marine sediments. However, recent investigations have revealed the production of various titania minerals through the alteration of volcanic rocks. Considering the occurrence of abundant volcanic rocks (e.g., volcanoclastics, seamounts, and oceanic crusts) in the oceanic environments, the activities of Ti may have been underestimated. Our study provides novel findings on the occurrence and growth mechanism of authigenic titania in the completely altered volcanic glasses collected from Line and Marshall seamounts by using multiple microanalytical methods. Both specimens primarily consist of mixed-layer illite/smectite (I/S), phillipsite, and carbonate-bearing fluorapatite, revealing that the volcanic glasses underwent palagonization processes. Scanning electron micrographs reveal numerous spherical Ti-rich shells with thicknesses of 450–1000 nm, enveloping spherical mixed-layer I/S aggregates with diameters of dozens to hundreds of microns. From the center to the edge of the spherule-shell structures, the concentration of Ti significantly increased. Further analysis using transmission electron microscopy confirms the presence of authigenic Fe-bearing titania particles within these Ti-rich shells. These titania shells likely form as a result of the migration of dissolved Ti(IV) ions and titania nanoparticles, which fill, nucleate, and aggregate at the interfaces of microspherules originally present in the volcanic glasses, ultimately coalescing into micron-sized particles through oriented attachment. Additionally, numerous titania nanoparticles, with aggregate sizes of 4–32 nm, were observed in the pore spaces of the mixed-layer I/S aggregates, likely be those trapped during Ti migration. Brookite is the dominant titania phase in both the titania shells and the smectite pores, with rutile and anatase occasionally present in the titania shells, implying the continuous mineral phase evolution during the growth of titania particles. The occurrence and distribution of titania suggest short-distance migration of Ti during palagonization processes. These findings offer new insight into the brookite formation and the Ti mobilization in basic and oxygen-rich marine environments, which is crucial for understanding the marine geochemical behaviors of Ti. [ABSTRACT FROM AUTHOR]

Within its location on the Çine plain, south of the Great Meander River, Çine-Tepecik is an important settlement inhabited continuously from the Chalcolithic to the end of the Bronze Age. Çine-Tepecik reflects an advanced lithic assemblage based on different raw material resources from the earliest period. Obsidian is among the earliest finds in Tepecik showing interregional trade based on the system of exchange, and is a resource that societies prioritized in their social lives and interregional communication since the beginning of the settlement process. Starting from the 4th millennium BCE until the end of the 2nd millennium BCE, obsidian was obtained from three main resources in the Aegean. These are Melos and Antiparos from the Cyclades; Giali from the Dodecanese and Göllü Dağ, Nenezi and Acıgöl from Central Anatolia. These connections, based on trade with the Aegean and Central Anatolia, reveal a skilled craft of obsidian tool production, as well as an obsidian and rock crystal vessel tradition in Tepecik during the Middle Bronze Age. The assemblage, which has a special meaning among prestige products, belongs to a craft activity that requires skill and experience, and is an indicator of socio-cultural richness. During the 2nd millennium BCE, in the wide geographical region covering Anatolia, Aegean and the Eastern Mediterranean obsidian and rock crystal vessels were among the special items produced for the royal or elite class. The stone vessel assemblage reflects the political and economic power of these regions, and also provides an understanding of interregional cultural and commercial connections. In the Çine-Tepecik Middle Bronze Age settlement, the obsidian and rock crystal vessel traditions followed a similar chronological development as the geography extending to Anatolia, the Aegean and the Eastern Mediterranean, and brings new finds to regional archaeology. [ABSTRACT FROM AUTHOR]

There is extensive geologic evidence of ancient volcanic activity on the Moon, but it is unclear how long that volcanism persisted. Magma fountains produce volcanic glasses, which have previously been found in samples of the Moon’s surface. We investigated ~3000 glass beads in lunar soil samples collected by the Chang’e-5 mission and identified three as having a volcanic origin on the basis of their textures, chemical compositions, and sulfur isotopes. Uranium-lead dating of the three volcanic glass beads shows that they formed 123 ± 15 million years ago. We measured high abundances of rare earth elements and thorium in these volcanic glass beads, which could indicate that such recent volcanism was related to local enrichment of heat-generating elements in the mantle sources of the magma. [ABSTRACT FROM AUTHOR]

A recent obsidian provenance study in three sites in the Valle de Altar region of northern Sonora has greatly expanded our understanding of the prehistoric relationship between the southern and northern Sonoran Desert. Based on obsidian source provenance, archaeological sites in the Valle de Altar indicate that contact with the region as far north as west-central and northern Arizona, the northern portion of the Papaquería, the Sierra Pinacate, the Sierra Madre Occidental, and the Basin and Range of Chihuahua was potentially frequent. However, the vast majority of artifacts produced from obsidian were procured apparently locally from an, as yet, unlocated source called here "SON Valle de Altar Unknown." The purpose here is to discuss the relevant regional geology, the source provenance of the obsidian artifact assemblage, and relationships throughout the greater Sonoran Desert. This project also adds significant data to the Southwest Archaeological Obsidian Project (). [ABSTRACT FROM AUTHOR]

Reliable reconstructions of tephrostratigraphy and emplacement mechanisms of Early to Middle Miocene volcaniclastic deposits across the Alpine-Mediterranean region may yield important clues as to the nature, spread, volume, magnitude and frequency of large silicic eruptions of the Carpathian-Pannonian Region. Here we report on a sequence of Middle Miocene volcaniclastic deposits intercalated with lacustrine strata from the Livno-Tomislavgrad Basin, part of the Dinaride Lake System. We applied a multi-proxy approach to elucidate their source, decipher their emplacement mechanism, and evaluate their basin-scale and regional correlativity. New high-precision zircon geochronology (~ 14.32 Ma) reveals their simultaneity with numerous volcaniclastic deposits (and their alteration products) widely spread across the Alpine-Mediterranean region. Additionally, their correlativity is confirmed at the scale of the Livno-Tomislavgrad Basin, based on similar lithostratigraphy, mineralogy and volcanic glass geochemistry. Newly obtained zircon Hf isotope data imply that Livno-Tomislavgrad Basin distal volcaniclastic deposits and ~ 14.36 Ma Harsány ignimbrite of the Carpathian-Pannonian Region had shared a parental eruptive center. However, different volcanic glass geochemistry, bolstered by the high-precision geochronology, suggests distinct eruption events, implying more frequent explosive volcanism of the Carpathian-Pannonian Region during Middle Miocene than previously recognized. We suggest that the ~ 14.32 Ma fine fallout tephra, deposited in the distal basin in the Dinarides (> 400 km from the source), was likely re-mobilized by water-driven hillside erosion from the extensive paleo-relief, and further transported via land-derived gravity flows. Upon entering the lake, the gravity flows likely transformed into subaqueous sediment density flows. These deposited ~ 1 to 7-m-thick overall graded volcaniclastic turbidites, thinning away from the presumed source of tephra re-mobilization. Although over-thickened, the ~ 14.32 Ma Livno-Tomislavgrad Basin volcaniclastic deposits can still serve as a reliable tephro- and tectono-stratigraphic markers due to their rapid mode of accumulation. Schematic illustration of the formation of studied ~14.32 Ma volcaniclastic successions of the SE Livno-Tomislavgrad Basin, Dinaride Lake System [ABSTRACT FROM AUTHOR]

This experimental study aims to contribute to functional analysis research on tools which specifically served to work wood and non-woody plants. They were made of obsidian and other volcanic rocks (basalt, trachyte, and phonolite) characterised by an amorphous matrix and phenocrysts of different number and size. In spite of prior functional analysis research resorting to these raw materials, there remain gaps in our understanding of specific activities. The work thus focused on working different types of wood from the Canary Island as well as on harvesting cereals. It is likewise centred on craftwork, especially regarding certain rarely studied contact materials such as palm leaves and rushes. The results reveal use-wear differences stemming from working woody and non-woody plants with both obsidian and other volcanic rocks. A special attention was given to the identification and description of the different features depending on the raw materials and the characteristics of their knapped surfaces. Identifying the combination of attributes has been essential to attain more accurate diagnostics. There are limits to each of the types of raw materials. The surfaces of obsidian are easier to observe and allow more specific identifications. In turn, the heterogeneous surfaces of volcanic rocks with phenocrysts that require more to time to develop diagnostic traces render use-wear amongst these types of rocks more difficult to observe. It is possible to distinguish longitudinal and transversal actions between woody and non-woody plants on every rock. Actions related to basketry, such us splitting and scraping, are more complicated to identify. The state of the worked plant (dry or fresh) and the time of use are key factors to consider in each case. [ABSTRACT FROM AUTHOR]

The Caribbean islands witnessed a population expansion of ceramic‐using horticulturalists during the Early Ceramic Age (ca. 500 BC to 750 AD) from the Orinoco Valley to Puerto Rico. We examined 18 lithic artefacts from Guadeloupe and Dominica initially thought to be obsidian, a material believed to be absent from those islands. We investigated the volcanic or meteoritic origin of this unique and yet unknown material through observation (binocular, SEM, microtomography) and geochemical analyses (PIXE, SEM‐EDS, ED‐XRF, EPMA, LA‐ICP‐MS). Elemental analyses rule out the hypothesis of an origin from a meteoritic impact (i.e. identification as tektites). Most of the artefacts have an andesitic composition (<63% SiO2), which appears to be unique among 'massive' glasses. The only artefact with a rhyolitic composition has been traced back to the Guadeloupe's Volcan du Tuf, where glassy fragments have been collected and analysed. The geological source of the other vitreous artefacts that exhibit an andesitic composition could be from a sublocal subduction‐arc volcanism (maybe from Martinique), although no volcanic vitreous material of this kind has ever been reported worldwide. These results once again highlight the regional mobility of Early Ceramic populations and the production of standard lithic products using a highly original, albeit low‐quality, local lithic resource, and provide valuable references for future identification of similar materials. [ABSTRACT FROM AUTHOR]

This paper explores the strategies implemented by hunter-gatherer groups in Southern Patagonia during the Late Holocene in relation to the circulation of goods and information. Previous archaeological investigations have revealed important changes in human mobility and land-use patterns during this period, associated with increasingly dry environmental conditions. In this context, we undertake a broad spatial scale analysis of the circulation of goods and information through the integrated examination of two lines of evidence: rock art and lithic raw materials. Specifically, we consider the distribution of engravings and black obsidian artefacts assigned to the Late Holocene. The former can offer certain insights into the circulation of information, and the latter are indicative of the circulation of goods. Our analysis suggests that during this period different strategies were developed by hunter-gatherer groups to face the changing environment. Several implications concerning social interaction and the movement of people during this period in Southern Patagonia are discussed. [ABSTRACT FROM AUTHOR]

Background: Sphincter-preserving techniques like autologous compound platelet-rich fibrin foam have gained popularity, offering potential for better functional outcomes in anal fistula treatment. The present study aimed to evaluate the efficacy and safety of Obsidian RFT®. Methods: The study conducted a retrospective analysis from January 2018 to December 2022 on patients who received anal fistula closure with Obsidian RTF® at the Department of General Surgery, Medical University of Vienna. Clinical diagnosis, complemented by radiographic imaging, was employed to confirm inconclusive cases. Demographic and fistula characteristics and postoperative data were collected from electronic records following STROCSS criteria. Results: Fifteen patients received Obsidian RFT® treatment for anal fistulas. We found no intra- and postoperative complications. The median hospital stay was 3 days. After a median follow-up of 32 months, a closure rate of 53.3% was detected. Non-significant differences were observed in various variables, yet trends emerged, indicating associations between abscess presence and non-healing fistulas. A distinct age threshold (≥ 42.7 years) served as an indicator for an inability to achieve anal fistula cure. Conclusion: Obsidian RFT® represents a safe, minimally invasive operative procedure. Approximately half the patients experienced healing, with better outcome in a younger population. Trial Registration: Ethical Approval number Medical University of Vienna (#1258/2018). This study was registered retrospectively in ClinicalTrials.gov (NCT06136325). [ABSTRACT FROM AUTHOR]

Geopolymer mortars, which cause less CO2 emissions than concrete and its raw material cement, are an innovative, environmentally friendly and sustainable building material. Geopolymers are formed by activating silica and alumina materials with alkaline activators. In this study, a geopolymer mortar containing obsidian (OB), also known as volcanic glass, which is free, and silica fume (SF), which is the waste material of the silicon and ferrosilicon industry, was investigated. The behavior of OB‐based geopolymer mortars under different curing times ranging from 2 to 120 h and different thermal treatment temperatures such as 90, 150, and 200°C were examined. The effectiveness of OB and SF on the physical features, compressive strength (CS), and micro‐structural of the geopolymers were characterized. Results demonstrated that the peak CSs were acquired in 96 h at 90 and 150°C heat treatment temperatures, while the highest CSs were acquired in 72 h for specimens subjected to 200°C heat treatment. Reduces in CSs were detected when the curing time exceeded the ideal limit. OB‐based geopolymer was found to be stable with SF and there was a linear relationship between SF substitution ratio and CS. The density of the mortar pieces decreased with increasing thermal curing hours. Devolving on the thermal temperature and curing time, the microstructures became more compact and microvoids and cracks decreased. It was observed that SF substitution reduced the total pore size of the geopolymers and allowed the pore structure size to be reduced. The results obtained from the study are expected to encourage the utilize of industrial wastes and new binders in the manufacture of geopolymers. [ABSTRACT FROM AUTHOR]

The reconstruction of paleo‐elevation serves a dual purpose to enhance our comprehension of geodynamic processes affecting terrestrial landforms and to contribute significantly to the interpretation of atmospheric circulation and biodiversity. The oxygen (δ18Ow) and deuterium (δDw) isotopes in atmospheric precipitation are systematically depleted with the increase of altitude, which are typical and widely applicated paleo‐altimeters. The utilization of hydrogen isotope of hydrous silicate minerals within the shear zone system, volcanic glass, and plant leaf wax alkanes offers valuable insights for addressing evaporation and diagenesis. In this paper, we review the principle, application conditions, and influencing factors of the hydrogen isotope paleo‐altimeter. In addition, we discuss the feasibility of utilizing this technique for quantitatively estimating the paleo‐elevation of the southeastern Tibetan Plateau, where multiple shear zones extend over hundred kilometers parallel to the topographic gradient. [ABSTRACT FROM AUTHOR]

Here we present a taxonomic treatment for the Brazilian species of Syrbatus (Reitter, 1882), including the description of three new species (Syrbatus moustache Asenjo & Valois sp. nov., Syrbatus obsidian Asenjo & Valois sp. nov. and Syrbatus superciliata Asenjo & Valois sp. nov.) from the Quadrilátero Ferrífero (Minas Gerais, Brazil). In addition, we designated lectotypes for the Brazilian species of species-group 2, Syrbatus centralis (Raffray, 1898), Syrbatus hetschkoi (Reitter, 1888), Syrbatus hiatusus (Reitter, 1888), Syrbatus transversalis (Raffray, 1898), and Syrbatus trinodulus (Schaufuss, 1887), besides recognizing the holotype for Syrbatus brevispinus (Reitter, 1882), Syrbatus bubalus (Raffray, 1898), and Syrbatus grouvellei (Raffray, 1898). The mitochondrial genomes (mitogenomes) of the three new species are presented, for which we present the phylogenetic placement among Staphylinidae with previously published data. [ABSTRACT FROM AUTHOR]

We examine provenance data collected from three types of geological resources recovered at Goat Spring Pueblo in central New Mexico. Our goal is to move beyond simply documenting patterns in compositional data; rather, we develop a narrative that explores how people's knowledge and preferences resulted in culturally and materially determined choices as revealed in those patterns. Our analyses provide evidence that residents of Goat Spring Pueblo did not rely primarily on local geological sources for the creation of their glaze paints or obsidian tools. They did, however, utilize a locally available blue-green mineral for creation of their ornaments. We argue that village artisans structured their use of raw materials at least in part according to multiple craft-specific and community-centered ethnomineralogies that likely constituted the sources of these materials as historically or cosmologically meaningful places through their persistent use. Consequently, the surviving material culture at Goat Spring Pueblo reflects day-to-day beliefs, practices, and social relationships that connected this village to a broader mosaic of interconnected Ancestral Pueblo taskscapes and knowledgescapes. [ABSTRACT FROM AUTHOR]

In Moncongloe area, Maros Regency, South Sulawesi Province, Indonesia, zeolite mineralization in porphyritic rhyolite and green tuff was identified occurred in a volcano-sedimentary sequence, members of the Miocene Camba Formation. This paper describes a recent study of the zeolite mineralization on the basis of field and laboratory data, which focused on its genetic aspects and potential utilizations based on its mineralogical and chemical characteristics. The laboratory works applied in this study include mineralogical analysis (petrography and XRD) and bulk chemical analysis (XRF for major oxides, ICP-OES and ICP-MS for trace elements). Microscopic and XRD studies indicate that the zeolite is a phillipsite type, which is associated with smectite, and was formed as an alteration product of the primary K-feldspar phenocrysts as well as fine crystalline ground mass and volcanic glass. The presence of phillipsite-type zeolite associated with smectite were also confirmed by the chemical compositions. The zeolite mineralization associated with smectite in the study area were formed by alteration process by hydrothermal fluid in alkaline seawater condition, during Late Miocene to Pliocene. So, it can be concluded that the hydrothermal alteration is occurred in that time range. The magma that forms the volcanic host rocks is an alkaline series magma, intermediate to acid in composition, and originates from subduction zone.The K-rich phillipsite-type zeolite in the study area can be used for, among other things: to remove lead from water, remove paraquat from wastewater, extract potassium from seawater, remove thorium from carbonate solutions, as catalyst in knoevenagel, as dietary supplementation for pets, to uptake ammonia in water, and for colorectal cancer therapy. [ABSTRACT FROM AUTHOR]

The application of Social Network Analysis to the study of archaeological networks has become increasingly common around the world, with a proven track record of processing large, complex, spatial and temporal archaeological datasets. This study builds upon previous network‐based analyses of interaction between communities of the Lapita Cultural Complex, with a specific focus on the Early Period (c.3300/3200–3100 calBP) in the Bismarck Archipelago, Papua New Guinea. Employing motif inventories from 13 Early Lapita Period assemblages, motif similarity and Centrality Analysis are undertaken, with the results compared to data from portable material culture, particularly obsidian and pottery, to further define the networks of interaction that linked communities during this period. We conclude that motif similarities and Centrality Analysis scores show good agreement with patterns of interactions established from the analysis of other types of portable material culture, which together support the existence of northern west to east and southern obsidian distribution networks, comprised of communities that employed unique types of interaction tailored towards their own cultural and societal circumstances and needs. Finally, we further conclude that these two networks may have arisen during the initial formation of the Lapita Cultural Complex, as populations established new social connections with other settler communities and incumbent populations across the region to survive in a new and foreign environment. [ABSTRACT FROM AUTHOR]

Konak Asarı is located in a plateau and forested area in the southeast of Eşme district in Uşak, Central Western Anatolia. In the settlement located on a high ridge to the east of Asar Hill, various pottery shards and chipped stone tools that contribute to prehistoric research in the Uşak region were identified. This settlement, dating back to the Neolithic Age, has cultural relations with the settlements in its immediate surroundings and in the Upper Menderes valley. It is also connected to Sarıgöl, Alaşehir plains and Manisa-Gediz region. There is little diversity in form among the brown, red and grey slipped pottery dating back to the 7th millennium BC. Apart from the bowls and pots consisting of undecorated examples, many flint tools were identified. Three flint cores were found, indicating the production of chipped stone tools in the settlement. Additionally, 2 obsidian tools were identified. The settlement findings are similar to the Upper Menderes Valley, Lakes Region and Western Anatolian coastal settlements. Konak Asarı provides descriptive data about the Neolithic Age settlements of the Uşak Region, specifically Western Anatolia, and its pottery typology and chipped stone tool technology. [ABSTRACT FROM AUTHOR]

Purpose: One of the low-cost minerals that can be used as reinforcing filler in polymer industry is pumice powder. Pumice is a highly porous volcanic glass formed during explosive eruptions. This pumice has received significant interest because of its large surface area with various polar groups and can be processed easily. Design/methodology/approach: This study is carried out to investigate the effect of partial replacement of silica (as traditional filler) by naturally occurring pumice powder to improve the thermal and mechanical properties of nitrile butadiene rubber cured with electron beam radiation (doses from 25 to 150 kGy). Findings: The results indicated that the addition of pumice powder increase the tensile strength at lower doses up to 75 kGy (especially at concentration of 5 phr). Besides, an improvement in the thermal stability was attained with the addition of pumice powder. Originality/value: Pumice powder is volcanic-based alumina and silica which is mainly composed of SiO2. It has porous structure which is formed by dissolved gases precipitated during the cooling as the lava hurtles through air. Due to its porous structure, it has low density and high thermal insulation. It also has high temperature and chemical resistance, for these reasons it became preferable material to be used as filler in the plastic and rubber industry. [ABSTRACT FROM AUTHOR]

Candidate glaciovolcanic landforms have been identified across Mars, suggesting that volcano‐ice interactions may have been relatively widespread in areas that once contained extensive surface and near‐surface ice deposits. To better constrain the detection of glaciovolcanism in Mars' geological record, this study has investigated and characterized the petrology, geochemistry, and mineralogy of three intraglacial volcanoes and an interglacial volcano in the Þórisjökull area of southwest Iceland. Our results show that glaciovolcanism creates abundant, variably altered hyaloclastite and hyalotuff that is sufficiently geochemically and mineralogically distinctive from subaerially erupted lava for identification using instruments available on Mars rovers and landers. Due to the lower gravity and atmospheric pressure at the surface of Mars, hyaloclastite and hyalotuff are also more likely to form in greater abundance in Martian glaciovolcanoes. Our results support that magmatism following deglaciation likely triggers decompression melting of the shallow mantle beneath Iceland, creating systematic changes in geochemistry and mineralogy. Glaciation can also suppress magmatism at its peak, encouraging the formation of shallow fractionated magma chambers. As such, it is possible for the crustal loading of an ice cap to enhance igneous diversity on a planet without plate tectonism, creating glass‐rich, altered, and mineralogically diverse deposits such as those discovered in Gale crater by the Curiosity rover. However, as the eroded products of glaciovolcanism are similar to those formed through hydrovolcanism, the presence of a glaciovolcanic landform at the source is required to confirm whether volcano‐ice interactions occurred at the sediment source. Plain Language Summary: The ancient Martian climate has been long debated with scientists hypothesizing that the river channels and lake beds preserved on the surface today formed in either a warm and wet environment or a cold and icy environment, with heating events driving large‐scale melting. One such heating event includes volcanism. This study investigated the chemical and mineralogical impact of volcano‐ice interactions in Iceland using techniques available to Mars rovers and landers to improve the detection of these deposits on Mars. Our results show that deposits rich in glass and the early products of low temperature alteration (palagonite, clays, zeolites) are likely to be more prevalent on Mars compared to the Earth due to differences in gravity between the two planets. Furthermore, the presence of a thick ice cap on Mars may encourage a diversity of lava compositions to form in shallow magma chambers as the weight of a thick ice cap can suppress volcanism. These types of deposits are identifiable using Mars rover and lander techniques, but due to their similarities to other volcanic units that may have erupted in the presence of water, a candidate glaciovolcanic landform is needed to confirm that these deposits are from volcano‐ice interactions. Key Points: Glaciovolcanism creates large deposits of altered fragmented volcanic glass distinct from subaerial volcanismGlaciation can suppress magmatism, driving geochemical and mineralogical diversity in an area once deglaciation startsGlaciovolcanism may have occurred on Mars with explosive phreatomagmatic units more likely under Mars' planetary conditions [ABSTRACT FROM AUTHOR]

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We describe an analysis of the flaked stone tools recovered from households in the Postclassic central Mexican city of Calixtlahuaca (a.d. 1130–1530). Most artifacts are obsidian and represent the blade-core technology, but biface and bipolar artifacts are also represented. Even though household residents were involved in limited biface and bipolar reduction, it appears that the city did not have any resident blade producers. This finding is at odds with the views of many archaeologists, who tend to associate craft production with the emergence of complex Mesoamerican urban centers. We examine the technologies from temporally distinct Calixtlahuacan household assemblages. We discuss why the quantity and quality artifacts associated with blade production are not consistent with resident blade making in the city. Finally, we examine four models for blade provisioning: (1) whole-blade trade, (2) processed-blade trade, (3) long-distance itinerant craftsmen, and (4) local, hinterland-based craftsmen. Evaluating how the Calixtlahuacans got their flaked stone tools has important implications for the comparative understanding of the organization and scale of economic provisioning systems in Postclassic central Mexico. This analysis supports new inferences about the nature of commercial networks that supplied the Toluca Valley prior to the arrival of the Spanish in the sixteenth century. [ABSTRACT FROM AUTHOR]

Clay-type Li deposits are poised to play a pivotal role in addressing the surging global demand for Li. The McDermitt clay-type Li deposit, located in Nevada, is the largest Li deposit in the United States, with Li hosted by a clay-rich sequence of smectite-dominated intervals and illite-dominated intervals, respectively. However, the occurrence of Li and the genesis of Li-bearing minerals within smectite-dominated intervals have not been thoroughly investigated in previous research. Here, we studied the mineralogy, the in-situ Li distribution, and the bonding environments of Li within the smectite intervals using a combination of instrumental techniques including scanning electron microscope, transmission electron microscope, time-of-flight secondary ion mass spectrometry, and nuclear magnetic resonance. Our results indicate that the smectite exhibits low crystallinity characteristics of lacustrine clay authigenesis and is commonly found to fill the interstices among volcanic minerals or envelop them; Li is mainly hosted by Mg-smectite rather than the volcanic minerals. Within the tuffaceous sediment samples, the volcanic glass has undergone a transformation, resulting in its complete disappearance and alteration into clay minerals. Owing to the octahedral sites of Mg-smectite bounded in Li, it is referred to be hectorite. We interpret that the hectorite's precipitation occurs in a high saline-alkaline water environment, a result of McDermitt tuff dissolution. This conclusion can be supported by the coexistence of spherulitic calcite and hectorite. Overall, this study confirms hectorite as the main Li-bearing mineral and increases the understanding of the genetic model of hectorite formation in intracontinental caldera basins. [ABSTRACT FROM AUTHOR]

Detection of extra-terrestrial geochemical components in melt generated during meteorite impact provides diagnostic evidence that can be used to confirm a hypervelocity impact event, and in some cases, classify the projectile. However, projectile contamination is often present at sub-percent levels, and can be difficult to detect. In contrast, meteoritic abundances in glass from small impact craters (<1 km diameter) formed by iron meteorites can be anomalously high, which has been attributed to glass originating from the projectile-target interface. Emulsion textures, immiscible liquids, metal spherules, and non-meteoritic siderophile element ratios have been cited as evidence that the projectile component is typically fractionated in impact glass. Here we present compositional data for impact glass from the Henbury crater field in Australia, where the largest crater is 145 m in diameter and the subgreywacke target rock and IIIAB iron projectile are geochemically distinct. Mixing models (Fe-Si, Ni-Co, Cr-Ir) and high platinum group element abundances indicate average projectile contributions ranging from 3 to 13 % in Henbury glass, comparable to ranges reported in glass from the Kamil (Egypt) and Wabar (Saudi Arabia) impact craters. However meteoritic siderophile element ratios (Fe:Ni, Fe:Co, Ni:Co) in Henbury glass appear nearly unfractionated, whereas Wabar and Kamil glasses have more fractionated ratios. Observed variations are attributed to fractionation of meteoritic Ni by formation of immiscible Ni-rich spherules during oxidation of meteoritic iron, and subsequent separation of Ni-rich spherules from glass during ejection. The Henbury glass sample analyzed is interpreted as an example of an interface melt that quenched prior to extensive oxidation and phase separation, and thus may represent one of the least fractionated samples of melt from the projectile-target interface described thus far, whereas Wabar and Kamil glasses record more evidence of fractionation processes. These results further highlight the influence of metal spherule formation on the composition of ejected glass from small impact structures formed by iron meteorites and provide new insights that explain textural features observed in natural impact glasses. [ABSTRACT FROM AUTHOR]

The glass phase in volcanic rocks presents a challenge to obtaining compositional data from visible and short‐wave‐infrared (VSWIR) and mid‐infrared (MIR) spectral data of remote surfaces due to its amorphous structure and variable composition. Nonetheless, glass is a common phase in volcanic materials because it forms via the rapid quench of magma and can constitute up to the entirety of a volcanic deposit. Use of partial least squares regression (PLS) to predict glass contents creates models that are insensitive to viewing geometry and sample conditions such as grain size and spectrally inactive compositional variables, enhancing the ability to detect glasses with remote sensing. PLS models are used here to predict crystallinity and oxide composition of samples from VSWIR and MIR spectral data using training spectra from natural volcanic rocks and geologically relevant synthetic samples. Three spectral resolutions of VSWIR and MIR spectra (1, 10, and 100 nm/band, and 1.9, 19, and 190 cm−1/band, respectively) were tested to assess the effects of collection configuration on different spectrometers. PLS models trained on 1 nm and 1.9 cm−1 data sets have the lowest uncertainties of glass modal abundance for VSWIR and MIR, respectively. MIR models predicting sample wt. % SiO2 and FeO, and VSWIR models of wt. % FeO provide accurate estimates (e.g., RMSE‐P of 3.4 wt. % FeO) at all spectral resolutions. Results are based on training data sets skewed to mafic compositions, which affects model accuracies. Plain Language Summary: Glass is difficult to identify and characterize from remote sensing observations of volcanic rocks. Differences in the number of spectral bands between laboratory and currently orbiting instruments further complicate interpretation of remote observations because glass features are subtle. A machine learning regression technique (partial least squares, or PLS) is used to predict the amount of glass and chemical composition using reflectance and emission spectral data of natural volcanic and synthetic glass samples. Results from three spectral resolutions were compared and affirm that spectral data can quantify phase abundance and composition in natural glassy samples such as volcanic materials. Key Points: PLS models can predict the modal glass abundance of volcanic samples with accuracies of 12%–15% from VSWIR and MIR spectraPLS models can predict bulk sample oxide abundances with accuracies of 1.5–6.9 and 0.9–4.2 wt. % from VSWIR and MIR spectra, respectivelyPLS model accuracy is minimally impacted by the number of available spectral bands [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Statement of the problem: Multiple firing cycles and different temperatures may adversely affect the mechanical properties of ceramic restoration.Objective: This study was designed to evaluate the effect of multiple firing cycles with different firing temperatures on the Flexural strength and Micro shear bond strength of the lithium silicate.Materials and methods: Specimens of Lithium Silicate (obsidian) were divided into 2 groups according to the tests done. The first group, Obsidian blocks were sectioned into 36 bar-shaped samples for the three point bending test, according to ISO 6872 standard. While the second group, the blocks were used to prepare 32 slices for measuring microshear bond strength. Each group was then divided into four subgroups according to the number of the firing cycles which were 1, 2, 3 and 5 firing cycles respectively. The flexural strength and microshear bond strength were measured separately.Results: For the first group, the highest flexural strength value was found in control samples, while the lowest value was found in 3 cycles’ samples. As for the second group, the highest micro shear bond strength value was found in samples subjected to 3 cycles, while the lowest value was found in 2 cycles’ samples. This shows that there was no significant difference between values of each group.Conclusion: Obsidian can be fired up to 5 firing cycles with no adverse effect on bond strength or flexural strength.

The chemical characterization of materials recovered from archaeological sites has been used to relate artifacts to their respective sources of raw material. For this, conventional methods of classical statistics are commonly used, such as bivariate graphs, cluster analysis and linear data transformations. Those who have applied these methods claim to have a high degree of confidence in the correct assignment of materials to their respective sources. However, if empirical data deviate from theoretical assumptions, classical statistical techniques can produce incorrect assignments. In this paper, we propose a semi-supervised learning procedure using clustering and classification based on models of mixtures of multivariate asymmetric exponential power distributions. The objective is to trace the origin and provenance of obsidian archaeological materials from the archaeological zone of Izapa, Chiapas, significantly optimizing the result of the correct allocation of unlabeled data by employing only limited supervision in the form of labeled instances. The effectiveness of the proposed method was evaluated by a controlled experiment using data from a set of geological samples from obsidian deposits. Subsequently, the method was applied to analyze a set of obsidian artifacts collected in excavations within Izapa dated for the Classic period. In both cases, well-defined classifications were obtained that, in the case of Izapa, allowed to determine the consumption of materials from Guatemalan sources, as well as some relationship with sources from western and central Mexico. [ABSTRACT FROM AUTHOR]

Volcanic glass has been used extensively as a paleoaltimeter. Deuterium (2H) concentrations in glass have been found to be stable over geologic timescales, making δ2H (also known as δD) a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in volcanic ash. Here, we analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ash-flow tuff, and create a paleoisoscape to assess variations in δD across Oregon during that time. To this end, 16 ash samples were collected across central and eastern Oregon from various flow units within the RST. Samples were analyzed for δD using a temperature conversion elemental analyzer (TC/EA) connected to a mass spectrometer and elemental composition using a scanning electron microscope (SEM). We compared the isotopic results to modern water and published ancient water proxy data to better constrain changes in climate and topography across Oregon throughout the Neogene. We also estimated wt. % H2O by calculating excess (non-stoichiometric) oxygen from SEM elemental data. We did not observe significant variations in δD among the flow units from single locations, nor was there a significant relationship between the prepared glass shard composition and wt. % H2O or δD, supporting the use of volcanic glass as a reliable paleoenvironmental indicator. Our results show significant spatial variation in δDwater values of RST, ranging from −107‰ to −154‰. δD values of ancient glass were similar to modern water near the Cascade Mountains but became relatively negative to the east near the inferred eruptive center of the RST, suggesting that a significant topographic feature existed in the vicinity of the RST eruptive center that has since subsided. [ABSTRACT FROM AUTHOR]

Lightning‐induced volcanic spherules (LIVS) are glasses produced by the rapid melting and solidification of molten volcanic ash grains. High temperatures generated by lightning will alter the physical and chemical properties of minerals exposed to the discharge. Laboratory experiments reveal that LIVS glass composition varies depending on the starting material, exhibiting heterogeneous compositional features common in other glasses created by cloud‐to‐ground lightning, nuclear explosions, and high velocity impact events. This study uses scanning electron microscopy, energy dispersive spectroscopy, and Raman spectroscopy to investigate the structure and Raman signatures of lightning‐induced glass spherules manufactured from five igneous minerals (<32 μm powders of albite, labradorite, augite, hornblende, and magnetite). LIVS were created through high‐current impulse experiments using peak currents of 25 and 40 kA. Analysis of the post‐experimental albite, labradorite, augite, and hornblende LIVS reveal primarily homogeneous silicate or aluminosilicate glasses with limited heterogeneity. Their amorphous Raman spectra are comparable to rhyolitic and mafic natural glasses along with Na2O‐K2O‐Al2O3‐SiO2, CaCO3‐Al2O3‐SiO2, and CaO‐MgO‐SiO2 synthetic glass networks. A few of the augite and hornblende LIVS spectra exhibit premelting effects, which occur below the melting point and represent the onset of cation disordering in phases that remain crystalline. Magnetite samples produced crystal‐rich, glass‐poor LIVS characterized by the growth of dendritic microcrystals and crystalline spectra that also contain a few bands alluding to the composition of their silicate–phosphate glass matrix. By understanding these chemical changes induced by lightning, we can extract information from other types of glasses produced during high temperature, short duration events. Plain Language Summary: High temperatures generated by volcanic lightning melt and fuse airborne volcanic ash grains consisting of mineral crystals and glassy fragments. Molten grains will rapidly quench into solid or hollow glass spheres termed lightning‐induced volcanic spherules, thereby altering the chemical and structural properties of the ash grains. This study utilizes Raman spectroscopy to characterize the structural properties of glass spherules produced from five common minerals (albite, labradorite, augite, hornblende, and magnetite) through lightning simulation experiments. Results reveal that lightning can alter these mineral samples irrevocably by transforming them into glass with complex compositions and Raman signatures corresponding to mineral and glass phases. The four minerals with a higher abundance of silica, a glass‐forming element, primarily produced chemically complex glass spheres with compositions representing a mixture of different melted minerals, and Raman signals similar to synthetic and naturally occurring glasses. In contrast, the post‐experimental spheres created from the silica‐poor, iron‐rich mineral magnetite are composed of newly formed iron micrometer‐sized crystals, limited amounts of glass, and Raman signals indicative of crystalline material. Although specific to volcanic ash, the impact of lightning on mineral fragments has broader implications for a wide range of geoscientists and planetary scientists. Key Points: Lightning simulation experiments conducted on powdered minerals produce particles containing both glass and crystalline phasesRaman spectroscopy of lightning‐induced spherules reveal spectra comparable to naturally occurring and synthetic multicomponent glassesCrystalline spectra derive from surviving mineral fragments and lightning‐induced crystallization of iron oxide dendrites [ABSTRACT FROM AUTHOR]

This comprehensive study analyzes the use of crushed glass as both fine and coarse aggregate in concrete, as well as the prediction accuracy of Artificial Neural Networks (ANN). The primary objectives are to understand the interactions between concrete’s constituents and to assess the accuracy of ANN models in predicting concrete’s mechanical and physical properties. This is achieved using a two-decade experimental results dataset of concrete’s compressive and tensile strengths, slump, density, and the corresponding mix design proportions, including waste glass aggregate. A series of 70 concrete samples were carefully built and tested, with compressive strengths varying from 12 to 71 MPa and glass aggregate percentages ranging from 0-100%. These samples served as the basis for the creation of an input dataset and ANN targets. The ANN model underwent intensive training, validation, testing, and statistical regression analysis. The ANN models are exceptionally accurate, with a continuously low error margin of roughly 2%, highlighting their usefulness in matching experimental and predicted results. Validation techniques highlight the models' dependability, with consistently high coefficients of determination (R-values), including 0.99484, demonstrating their robustness in replicating complicated concrete properties. The data analysis shows a unique pattern, with optimum glass aggregate percentages in the range of 10–20%. Beyond this range, there is a noticeable decline in concrete properties. Finally, the study confirms the efficacy of ANN in predictive modeling while also validating the potential of crushed glass to replace natural aggregates in concrete. [ABSTRACT FROM AUTHOR]

Traditional dissolution of geologic samples often requires a significant time investment. Here, we present an alternative method for the dissolution of geologic materials using laser-driven hydrothermal processing (LDHP). LDHP uses laser energy directed onto a submerged sample, which increases the temperature and pressure at the liquid–sample interface and drives the hydrothermal dissolution coupled with photomechanical spallation, an ablative process. This uses focused 527 nm laser energy at 40 W average power, 1 kHz pulse repetition rate, and 115 ns pulse duration. When LDHP is performed on basalt geostandards (BCR-2 and BHVO-2) using the conditions outlined, we show that LDHP does not produce significant elemental fractionation and, thus, can be considered an alternative processing method to traditional mechanical crushing and acid digestion. Additionally, it is possible using LDHP to utilize the spatially confined beam to target and selectively isolate individual phases in a rock, potentially alleviating the need for mechanical separation of inclusions that are difficult to physically isolate. Furthermore, using this outlined method of LDHP, we demonstrate full dissolution of 120 mg of obsidian in 85 minu, meaning that LDHP is a potentially very useful method when sample processing is time sensitive. [ABSTRACT FROM AUTHOR]

The Salado and Verde streams constitute the two main seasonally available freshwater courses that flow into the Atlantic coast of the Río Negro province (continental Patagonia, Argentina, 42° South). This would have favored their use in the past as corridors for human circulation between the coast and the interior. This paper presents the results of the technomorphological and geochemical analyses of the obsidian artifacts recovered in the area to constrain mobility. The results allow us to propose the existence of toolkit reconditioning or replacement activities, and the identification of different sources of provenance of the obsidians (Sacanana, Telsen, and Portada Covunco, distant up to 800 km from the study area), reinforcing the hypothesis of a coast–inland circulation, with the possible existence of circuits of exchange of this raw material. [ABSTRACT FROM AUTHOR]

Nucleation of H2O vapor bubbles in magma requires surpassing a chemical supersaturation threshold via decompression. The threshold is minimized in the presence of a nucleation substrate (heterogeneous nucleation, <50 MPa), and maximized when no nucleation substrate is present (homogeneous nucleation, >100 MPa). The existence of explosively erupted aphyric rhyolite magma staged from shallow (<100 MPa) depths represents an apparent paradox that hints at the presence of a cryptic nucleation substrate. In a pair of studies focusing on Glass Mountain eruptive units from Medicine Lake, California, we characterize titanomagnetite nanolites and ultrananolites in pumice, obsidian, and vesicular obsidian (Brachfeld et al., 2024, https://doi.org/10.1029/2023GC011336), calculate titanomagnetite crystal number densities, and compare titanomagnetite abundance with the physical properties of pumice to evaluate hypotheses on the timing of titanomagnetite crystallization. Titanomagnetite crystals with grain sizes of approximately 3–33 nm are identified in pumice samples from the thermal unblocking of low‐temperature thermoremanent magnetization. The titanomagnetite number densities for pumice are 1018 to 1020 m−3, comparable to number densities in pumice and obsidian obtained from room temperature methods (Brachfeld et al., 2024, https://doi.org/10.1029/2023GC011336). This range exceeds reported bubble number densities (BND) within the pumice from the same eruptive units (average BND ∼4 × 1014 m−3). The similar abundances of nm‐scale titanomagnetite crystals in the effusive and explosive products of the same eruption, together with the lack of correlation between pumice permeability and titanomagnetite content, are consistent with titanomagnetite formation having preceded the bubble formation. Results suggest sub‐micron titanomagnetite crystals are responsible for heterogeneous bubble nucleation in this nominally aphyric rhyolite magma. Key Points: Aphyric rhyolite eruptions staged from shallow magma reservoirs lack the overpressure needed for homogeneous bubble nucleationHeterogeneous bubble nucleation may occur on sub‐µm titanomagnetite crystals, which are undetectable using standard analytical techniquesSub‐µm titanomagnetite crystals can be detected and quantified with low temperature magnetic analyses [ABSTRACT FROM AUTHOR]

We document the presence, composition, and number density (TND) of titanomagnetite nanolites and ultra‐nanolites in aphyric rhyolitic pumice, obsidian, and vesicular obsidian from the 1060 CE Glass Mountain volcanic eruption of Medicine Lake Volcano, California, using magnetic methods. Curie temperatures indicate compositions of Fe2.40Ti0.60O4 to Fe3O4. Rock‐magnetic parameters sensitive to domain state, which is dependent on grain volume, indicate a range of particle sizes spanning superparamagnetic (<50–80 nm) to multidomain (>10 μm) particles. Cylindrical cores drilled from the centers of individual pumice clasts display anisotropy of magnetic susceptibility with prolate fabrics, with the highest degree of anisotropy coinciding with the highest vesicularity. Fabrics within a pumice clast require particle alignment within a fluid, and are interpreted to result from the upward transport of magma driven by vesiculation, ensuing bubble growth, and shearing in the conduit. Titanomagnetite number density (TND) is calculated from titanomagnetite volume fraction, which is determined from ferromagnetic susceptibility. TND estimates for monospecific assemblages of 1,000 nm–10 nm cubes predict 1012 to 1020 m−3 of solid material, respectively. TND estimates derived using a power law distribution of grain sizes predict 1018 to 1019 m−3. These ranges agree well with TND determinations of 1018 to 1020 m−3 made by McCartney et al. (2024), and are several orders of magnitude larger than the number density of bubbles in these materials. These observations are consistent with the hypothesis that titanomagnetite crystals already existed in extremely high number‐abundance at the time of magma ascent and bubble nucleation. Plain Language Summary: We use magnetism experiments to prove that nanometer‐sized magnetic particles are present in volcanic rocks with low iron content and few visible crystals. Nanolites (particles between 30 and 1,000 nm) and ultra‐nanolites (particles smaller than 30 nm) are extremely difficult to detect in volcanic rocks composed mainly of glass using conventional methods such as optical and electron microscopy. Titanomagnetite nano‐particles may play a role in controlling the explosiveness of volcanic eruptions. The magnetic signatures of minerals can be used to determine their chemical composition, particle size range, and particle abundance. Pumice and obsidian contain the mineral titanomagnetite, with no evidence of prolonged crystallization at high oxygen levels at the Earth's surface. Observed magnetic behaviors are very similar to those of previously published studies of titanomagnetite in the 10–1,000 nm size range, and similar to mathematical models that simulate this size range. We find that pumice clasts have a magnetic fabric, suggesting that the nanolites and ultra‐nanolites were aligned in spatial patterns before the magma solidified, with stronger alignment coinciding with high degrees of vesicularity. Our results indicate that titanomagnetite crystals are highly abundant, and had crystallized in the magma chamber before the eruption. Key Points: Magnetic methods document titanomagnetite nanolites in rhyolitic materials from Glass Mountain, Medicine Lake Volcano, CaliforniaTitanomagnetite number densities for pumice, obsidian, and vesicular obsidian span 1012 to 1020 m−3 of solid materialTitanomagnetite crystals already existed in extremely high number‐abundance at the time of magma ascent and bubble nucleation [ABSTRACT FROM AUTHOR]

Quantitative isotopic paleoaltimetry has been applied in regions where Rayleigh distillation controls isotopic lapse rates. Air mass mixing and moisture recycling are viewed as complicating factors. We show here that, because of such effects, a cross‐Andean transect of meteoric water δD values precisely marks the geographic position of the Western Cordillera crest. This modern water signal is also recorded in Pliocene‐Pleistocene hydrated volcanic glass δD values. δD values between the Pacific coast and Western Cordillera exhibit no trend up to 2.5 km elevation and 100 km inboard, consistent with an arid climate in which Amazonian moisture is topographically blocked and Pacific moisture is efficiently recycled. The result is a large δD lapse rate (−98‰/km) and an abrupt horizontal δD shift (2‰/km) at the Western Cordillera crest. Therefore, we conclude that cross‐orogen δD transects could locate the ancient Western Cordillera crest. Plain Language Summary: Mountains have an outsized control on climate. Moist air masses rise and cool to cross high elevations, resulting in enhanced precipitation on the windward side and dry conditions downwind These processes influence the isotopic compositions of rainfall and of materials preserved in the geologic record that form from the interaction of rain with near‐surface materials. Here we report data from transects across the Peruvian Central Andes and show that the isotopic compositions shift abruptly at the position of highest topography (the crest of the Western Cordillera). This suggest that isotopic compositions of materials preserved in the geologic record might help establish the geographic position of the crests of mountain belts in the past. Key Points: There is a substantial shift in the hydrogen isotope ratios of meteoric water at the Andean Western Cordillera crestVolcanic glass younger than 5 million years old shows similar ratio distributions to modern soil and precipitation water valuesVolcanic arc migration over time can be identified with meteoric water stable isotope records [ABSTRACT FROM AUTHOR]

An integrated morphological and chemical analysis of Arctic aerosols was undertaken for Icelandic dust and Svalbard aerosols to be compared by scanning electron microscopy coupled with EDS microanalysis (SEM–EDS) via imaging and chemical analysis techniques. Results of the characterization of the particles from both surface sediments and suspended dust from desert areas in Iceland confirmed that volcanic glass is an excellent marker of Icelandic dust origin. Classification diagrams of particle chemical composition clearly distinguished the volcanic glass particles from the local surface sediments at Hornsund, Svalbard. In the same diagrams, a few particles were found in the aerosols from Hornsund which were morphologically and chemically similar to the Icelandic volcanic glass particles. Such properties, in principle, cannot be considered exclusive to volcanic glass. However, since Iceland is the largest and the most active source of long-range transported dust in the northern European high latitudes, and air mass trajectories reaching Hornsund did, actually, pass Iceland before the aerosol collection in the period under consideration, these particles likely originated in Iceland. On the other hand, the comparison with local and Icelandic sediments revealed the presence in the aerosols from Hornsund of particle types that cannot be attributed to either local or Icelandic dust. This observation highlights the possibility of extending and validating the application of the proposed geochemical criterion to different dust sources across the Arctic and the sub-Arctic, provided a consistent geochemical databank of representative dust sources from these areas is arranged. [ABSTRACT FROM AUTHOR]

The experimental study of water–rock reactions under high-temperature and -pressure conditions is a useful approach to constrain controlling factors of the fluid composition in a natural hydrothermal system. Previous studies have focused mainly on the mid-ocean ridge fields, and the hydrothermal alteration of intermediate-to-felsic rocks has been less emphasized despite its potential importance in the fluid chemistry in an arc/back-arc basin setting. We examined the alteration processes of fresh rhyolite and andesite rocks collected from the middle and southern Okinawa Trough, respectively, at 325 °C and 300 bar (the estimated condition at the reaction zone in the fields), especially focusing on the behavior of silica between the solid and liquid phases. The experimental fluids are characterized by the high Si concentration up to 30 mM, indicating the substantial dissolution of volcanic glass in the analyzed rocks. The high Si concentration in the fluids was presumably buffered by amorphous silica, precipitated from the fluids as a precursor of hydrothermal quartz, during the experiments. Our results emphasize a previously overlooked role of volcanic glass/amorphous silica in the fluid composition in the Okinawa Trough and are consistent with the previous model of pumice replacement mineralization for the SMS deposit formation in the trough. [ABSTRACT FROM AUTHOR]

Northwest Africa (NWA) 7611/10480 are lunar regolith breccia meteorites, composed of mineral fragments and various clasts including mare basalts, volcanic glasses, gabbroic lithologies, and a diverse variety of highland materials (ferroan anorthosite, Mg‐suite, magnesian anorthosite, and alkali suite rocks) as well as different subvarieties of impact melt breccia. The Apollo two‐component mixing model calculation reveals that the NWA 7611 source region contains 58 wt% mare materials and 42 wt% highland components, but the estimated mare components in NWA 10480 have a higher abundance (66 wt%). The predominantly very low‐Ti (VLT) composition in both fine‐grained basaltic and coarse‐grained gabbroic lithologies indicates a provenance associated with a thick lava flow or a single magmatic system. The co‐occurrence of zoning patterns and fine‐scale exsolution lamellae in pyroxene debris supports a cryptomare deposit as the best candidate source. Phosphate Pb–Pb ages in matrix fragments, impact melt breccia, and basaltic clast indicate that the breccia NWA 7611 records geological events spanning approximately 4305–3769 Ma, which is consistent with the ages of ancient lunar VLT volcanism and the products of basin‐forming impacts on the lunar nearside. The youngest reset age at ~3.2 Ga is potentially related to the strong shock lithification process of breccia NWA 7611. Moreover, the similar petrology, texture, geochemistry, cosmic‐ray exposure data, and crystallization ages support that basaltic component in Yamato (Y)‐793274, and Queen Alexandra Range (QUE) 94281, NWA 4884, and NWA 7611 clan came from the same basalt flow. [ABSTRACT FROM AUTHOR]