Mineralogical Characteristics Research Articles

Towards sustainable construction: Strength and microstructural assessment of Dillenia suffruticosa and Acacia auriculiformis leaf ash as novel supplementary cementitious materials

Researchers are exploring local, recycled, and waste materials for construction to address environmental concerns. Concrete heavily depends on cement, contributing to energy consumption and greenhouse gas emissions. Substituting cement with alternatives like recycled materials can cut energy use and minimize the environmental impact on concrete production. This research represents the first investigation into using Dillenia Suffruticosa (DS) and Acacia Auriculiformis (AA) leaf ash as sustainable alternatives to cement in producing eco-friendly mortar, an area that other researchers have not previously explored. The study aims to investigate using DS and AA leaf ash as sustainable alternatives to cement in mortar production. In this study, the incorporation of DS and AA leaf ash as a partial replacement for cement was systematically varied in increments of 5 %, ranging from 5 % to 40 % of the total mortar volume. The ash was systematically incorporated into the mortar in increments of 5 %, ranging from 5 % to 40 % of the total mortar volume. The study further conducted a comprehensive investigation into the physical properties of the mortar, including consistency, bulk density, dry density, water absorption, and flow characteristics, alongside an analysis of its compressive strength. Microstructural behaviour was assessed using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and thermogravimetric analysis to provide a comprehensive analysis. Results indicate that the enhancement in compressive strength of DS ash specimens, relative to AA ash, ranged from 1.32 % to 24.49 % at 7 days, 5.81 %–16.86 % at 14 days, and 1.87 %–11.91 % at 28 days. Furthermore, the highest enhancement in compressive strength is observed with a composition containing 10 % DS ash and 5 % AA ash content, underscoring the superior performance of DS ash compared to AA ash. The mineralogical characteristics of DS and AA leaf ashes illustrate their effectiveness as supplementary cementitious materials in sustainable construction. The significant advantages of using DS and AA leaf ash as a cement substitute are environmental sustainability, innovative materials use, and contribution to sustainable construction.

Performance Evaluation of a Romanian Zeolite: A Sustainable Material for Removing Ammonium Ions from Water

Ammonium ion is a chemical species that is found in abundance in natural waters, whether underground or surface, but also in wastewater resulting from agricultural and industrial activities. Even if the removal of the ammonium ion from water has been studied for a very long time, it has been found that its removal is far from being solved. In this study, we evaluated the performance of the ammonium ion adsorption process on two adsorbents, zeolite clinoptilolite, ZR, a sustainable material (manufacturer: Zeolite Development SRL, Rupea, Brasov, Romania), and the other granular activated carbon type, Norit GAC 830 W. Zeolite ZR is found in very large deposits in Romania; it is a natural, cheap material with costs between 50 and 100 EUR/ton, compared to other adsorbents that cost over 500 EUR/ton and which can be regenerated and reused in the technological process of water treatment and purification, but also after exhaustion, as an amendment for the soil. In the first step, this paper presents the mineralogic (XRD) and structural (SEM and EDX) characterization of the ZR and the determination of the pH zero-point charge, pHZPC, for all the adsorbents. Studies were carried out in equilibrium and kinetic conditions. The efficiency of the adsorbent was investigated in different experimental conditions by varying the initial concentration, particle size, temperature, pH, ionic strength, and contact time. The mathematical models and parameters specific to the adsorption isotherms that best describe the experimental results were identified. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich mathematical models were used for comparison. The Langmuir isotherm proved to be the most appropriate to describe the adsorption of ammonium ions on all types of adsorbents used. The adsorption capacity of ammonium ions from synthetic solutions at 20 °C, pH = 6.09, for the range of initial concentrations 0–50 mg/L for Rupea zeolite is in the range of 10.46 mg/g−12.34 mg/g, and for granular activated carbon GAC W830, it is 16.64 mg/g. It was found that the adsorption capacity of the ammonium ion on both activated carbon and zeolite increases with increasing temperature and pH. Also, it was observed that as the ionic strength increases, the adsorption capacity decreases for all four adsorbents. Kinetic models were also identified that best describe the experimental processes. In this sense, pseudo-first order, pseudo-second order, intra-particle diffusion and the Elovich model were used. The results of the investigation showed that second-order kinetics governs the adsorption process on ZR, and pseudo-first order governs activated carbon.

MINERAL PHYSICS ANALYSIS OF ALLUVIAL ROCKS AS A SOURCE OF SHALLOW HYDROCARBON SEEPAGE IN BELIS VILLAGE, WARU BASIN, EASTERN SERAM ISLAND, MALUKU PROVINCE

Belis Village is located in the Waru basin adjacent to the Bula basin on the eastern part of Seram Island and has potential shallow hydrocarbon manifestations. This research aims to determine the mineralogical characteristics of the rocks that make up shallow hydrocarbon manifestations at the research location. The research method used is physical analysis of minerals including petrographic analysis and XRD methods. The analysis results of the XRD method show an abundance of quartz minerals at 58%, followed by clay minerals at 35%, opaque minerals at 25%, and the rest in the form of cavities while feldspar minerals are secondary minerals. The results of the XRD analysis show that the more dominant mineral is protoenstatite (MgSio3) with an average abundance of 70.33% as a carrier of shallow hydrocarbon seeps, Quartz (SiO2) with an average abundance of 18.46%, and Clinoestatite with an average abundance of 11.21% as a mineral associated with shallow hydrocarbon seeps.

Heavy metal migration and lithium isotope fractionation under extreme weathering of basalt on tropical Hainan Island, China

Basalt weathering can cause heavy metal enrichment in soils, and lithium isotopes serve as an effective tracer for this weathering process. However, the relations among weathering intensity, heavy metal migration, and Li isotope fractionation remain unclear. We conducted systematic examinations of a basalt weathering profile on tropical Hainan Island in China. The characteristics of mineralogy, elemental and Li isotopic geochemistry indicate that the profile has undergone changes from initial to advanced and ultimately extreme weathering stages. The corresponding dominant minerals are primary minerals, clay minerals such as kaolin-group, and the Al–Fe–Ti (hydro)oxides. The variations of Fe-group heavy metals within the profile are very similarly to that of Fe, exhibiting a pattern of loss-gain-loss. Newly formed secondary minerals preferentially incorporate lighter 6Li, leading to a gradual increase in Li content and a decrease in δ7Li. Due to the high δ7Li value of rainwater input, the ongoing impact of secondary mineral adsorption is partially counteracted. This results in the δ7Li of laterite and topsoil being maintained within a narrow range (−3.2‰ ∼ −1.9‰), despite the broader variation observed across the entire profile (−3.2‰ ∼ +2.8‰). Comparing basalt weathering profiles in different climatic zones reveals a very complex Li isotope behavior and its controlling factors. Therefore, it is essential to carefully evaluate the influence of atmospheric input, secondary mineral adsorption, dissolution, and redeposition processes on Li isotopes. Throughout the entire profile, Cr, Ni, and Cu exhibit enrichment relative to soil background values, indicating that the weathering of tropical basalt may pose potential environmental risks for these elements.

Structural detachment influences the shale gas preservation in the Wufeng-Longmaxi Formation, Northern Guizhou Province

Abstract In order to reveal the restriction in shale gas enrichment of the Wufeng-Longmaxi Formation in the northern Guizhou province, the influence model of detachment layer was established through field geological investigation, core observation, logging, sample analysis, and geological background data. The response relationship between the detachment layer and the shale gas enrichment model in different structural formats was analyzed. The results show that the thickness of the Wufeng-Longmaxi Formation’s detachment layer is influenced by the conditions near the fault zones and mineralogical characteristics. The lithofacies of the detachment layer shows mainly a combination of clay-rich shale facies. This indicates that lithofacies type is one of the main factors influencing the variation in slip layer thickness. The detachment layer exhibits distinct well logging response characteristics and is influenced by nitrogen enrichment. The development of detachment fractures allows atmospheric nitrogen to infiltrate shale gas. It leads to poor gas saturation in the shale gas. In addition, the overall tectonic deformation in the northern Guizhou province was found to gradually intensify from Northwest to Southeast, and there were two tectonic models: a slot-shift tape transition belt and a spacer type deformation belt. The influence of decollements on shale gas preservation was barely found in the northern Guizhou province. It is mainly controlled by buried depth of the target layer, conditions of the cover layer, structural type, and deformation intensity.

Formation of build-up in a cement kiln preheater: qualitative and quantitative mineral characterisation

Extracting more information about the reactions and parameters governing the formation of build-up in the preheater systems of clinker burning lines could be an efficient way of better attenuating build-up formation. In order to control the appearance of build-up, diagnosis steps of mineralogical analysis application for process optimisation (MAA-PO) are suggested. Mineralogical characterisation was carried out on three samples taken from different layers of the same build-up. Qualitative and quantitative X-ray diffraction, chemical analysis and Fourier transform infrared spectroscopy revealed that ternesite is the key mineralogical phase responsible for the growth and consolidation of build-up. Its appearance is governed by solid–solid reactions promoted by the available sulfate liquid phases, mainly calciolangbeinite, as well as C12A7 and C4AF. The hot-powder calcination degree, amount of sulfur trioxide, lime saturation factor, silica ratio and alumina ratio are the operational data that were correlated to the mineralogical analysis of build-up. Based on this correlation, it is possible to predict the reaction kinetics involved in each layer formation and to estimate the development time of each. The results showed that MAA-OP is a promising novel approach to optimise the process parameters in clinker production.

Occurrence, distribution and fate of iodine during phosphate ore beneficiation process

Numerous beneficiation techniques, such as washing, grinding, flotation, digesting, and calcination, are used to concentrate the minerals found in phosphate rocks, which include apatite, carbonatites, and silicates. Significant iodine levels are often found in phosphate ore minerals, which have a distinctive geochemical occurrence. However, the exact occurrence and distribution of iodine in these minerals are not yet thoroughly understood. A study was carried out to investigate the iodine's distribution, occurrence modes (phases), and release rate in Moroccan phosphate as it undergoes the beneficiation process. The samples underwent a multi-analytical approach combining mineralogical and chemical characterization using ICP-MS, ICP-OES, XRD, elements titration, and Pearson correlation analysis for interelement relationships. Calcination, digestion, and Heavy liquid separation is used to study the fate of iodine. The analysis indicates that iodine is primarily found in fluorapatite, with local concentrations ranging from 35 to 130 ppm. The most enriched grains/zones are associated with fluorapatite, enriched in P2O5, F-. in addition, iodine is positively correlated with its main components, including P2O5, F-, SO3, Na2O, CaO, and REEs. The flotation and heavy liquid separation process used for calcite and silicate removal is acting as an iodine and P2O5 concentrator, given that 99 % of iodine occurs in the apatite phase. However, it has been demonstrated that iodine can be released during the digestion of phosphate rock. Where the initial iodine content is distributed among phosphoric acid, PG, and the gaseous phase, constituting 35 %, 25 %, and 40 %, respectively. Furthermore, the calcination of phosphate rock between 800–1000 °C shows that total iodine is released with gases in I2 form, leading to an increase in the concentration of iodine in the surrounding area. In this regard, an integrated pyrometallurgical process has been proposed for the valorization of iodine as silver iodide. This process involves trapping gaseous iodine in an alkaline solution, followed by precipitation, thereby contributing to the overarching objectives of the circular economy and environmental protection.

Re-examination of vesbine in vanadate-rich sublimate-related associations of Vesuvius (Italy): Mineralogical features and origin

Abstract A set of 23 vesbine-bearing samples from Vesuvius volcano (Italy), preserved in the collection of the Royal Mineralogical Museum of Naples, University Federico II (RMMN), have been investigated to identify the mineral assemblages and their mode of formation. In the late 19th century, fumarole-related yellow patinas coating some historical lavas from Vesuvius were believed by Scacchi to contain a new element, vesbium, similar to vanadium in a mineral he called vesbine. Subsequent studies rejected vesbium and showed that vesbine was a poorly defined mixture of copper vanadates and halides. The vesbine samples studied here consist of yellowish to yellow-green-blue encrustations on Vesuvius lavas and have been analyzed by combined optical microscopy, SEM-EDS, XRPD, FTIR, and TEM-HRTEM-EDS. Results reveal complex mineral associations, including vanadates, halides, carbonates, oxides, silicates, tungstates/molybdates, and sulfates. The vanadates correspond to mottramite, volborthite, and vanadinite; subordinate amounts of descloizite were detected by XRPD and FTIR investigations. Several additional non-essential elements have been detected in the vanadates, including Mn, Zn, and As. The occurrence of wulfenite- and stolzite-rich phases indicates the presence of Mo and W, along with Pb, in the mineralizing fluids. Mn-rich phases, commonly in mixtures with silicates and vanadates, were also observed. These minerals are formed by a combination of different processes, including rock-fluid interactions, gas-water interactions, and alteration/oxidation of primary fumarolic minerals. Temperatures for the depositions of the vanadates-bearing assemblages are interpreted to be in the range of 100 to 400 °C.

A comparison of the proto-dolomite induced by cyanobacteria and halophilic bacteria: implications for dolomite-inducing microbe identification

This study investigates the morphological and mineralogical characteristics of proto-dolomite induced by two specific microorganisms with varying lifestyles: the extremely halophilic bacterium Vibrio harveyi QPL2 and the cyanobacterium Leptolyngbya boryana. Halophilic bacterially-induced proto-dolomite (HBD) and cyanobacterially-induced proto-dolomite (CBD) were subjected to comprehensive characterization techniques, including X-ray diffraction, scanning electron microscopy, Focused Ion Beam, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The results indicate that both HBD and CBD exhibit a low degree of crystallinity and possess comparable molar ratios of MgCO3 to CaCO3. Moreover, neither of them exhibits the ordered structure of ideal dolomite. HBD and CBD exhibit notable distinctions in external morphology and internal structure. HBD forms a subunit aggregate with a less dense surface and numerous pinhole structures resulting from bacterial survival. In contrast, CBD adopts a bispherical shape with a relatively dense surface and minimal indications of cyanobacterial survival. Both HBD and CBD have an internal hollow structure. However, HBD is characterized by sparse population and loosely arranged subunits, while CBD features only a central cavity. Additionally, HBD particles are smaller compared to CBD particles. These morphological differences suggest that HBD primarily grows through bacterial surface-dependent processes, whereas the growth of CBD is not directly reliant on the surface of cyanobacteria. Compositionally, the weight percentage of crystalline water in CBD exceeded that of HBD with a value of 29.42 % compared to 5.9 %. This increase in internal crystalline water enables a faster conversion of CBD to the ordered ideal dolomite in a specific diagenetic environment. This study implies that the morphology and composition of microbial proto-dolomite may aid in identifying the type of dolomite-inducing microbes.

Complex structure of the center Oktyabr’sky deposit, Norilsk district, Russia

The PGE-Cu-Ni Oktyabr’sky deposit, related to the Kharaelakh intrusion, contains the largest sulfide ore bodies in the world. Various models have been proposed to explain its formation based on the mineralogical and textural characteristics of the sulfide ores. However, the underlying structure of the intrusion, critical to understanding the deposit’s formation, has not been well studied until now. For the first time a 3D model of the center deposit with C-3 and C-4 orebodies representing its main part has been created. The model reveals that the intrusion in this area is a thin plate, rather than a tubular or honolithic body, as previously assumed. This morphology does not support the idea of ore formation by in situ reaction between primary magma and host rocks. Instead, sulfides were transported by magma from a deeper zone in the chamber. Within this area, two pulses of magma were identified, forming the Northern and Southern intrusive branches. They are similar in inner structure; however, some differences exist. The rocks of these intrusions are identical in terms of their major components but differ in metals (Cu/Ni ratios, Co, Zn, and V contents), which is particularly reflected in the composition of the chalcopyrite group of minerals. The picritic gabbro-dolerites presented in both intrusive bodies crystallized under similar conditions, namely, T and fO2, with an accuracy of the applied methods (±15 °C and ± 0.4 lgfO2, respectively) from two portions of magma that differ from those of the taxitic gabbro-dolerites. Therefore, the Oktyabr’sky deposit has a more complex structure in its central part than has been previously reported. Considering earlier published data from the western and eastern parts, it can be concluded that the Karaelakh intrusion consists of several intrusive bodies rather than a single large massif that should be consider in future models.

Preliminary Study on the Jinju Formation in the Gyeongsang Basin to Evaluate Host Rock for High-level Radioactive Waste Geological Disposal: Focusing on Lithological and Mineralogical Characteristics

Preliminary Study on the Jinju Formation in the Gyeongsang Basin to Evaluate Host Rock for High-level Radioactive Waste Geological Disposal: Focusing on Lithological and Mineralogical Characteristics

Nanoscale mineralogy and organic structure characterization of shales: Insights via AFM-IR spectroscopy

Nanoscale mineralogy and organic structure characterization of shales: Insights via AFM-IR spectroscopy

First geological survey and characterisation of a giant depression in carbonate strata at the Rio Grande Rise (southwestern Atlantic)

Pockmarks are submarine depressions often considered the result of fluid (gas and oil) expulsion from the seafloor. Recent geophysical surveys at the Rio Grande Rise (RGR - SW Atlantic) revealed extensive presence of seafloor depressions, generically interpreted as pockmarks. To date, direct observations or sampling from these depressions are lacking. Moreover, hydrocarbons have never been detected at the site, questioning the possibility of pockmarks formation by fluid expulsion. Here we present the first visual inspection and rock characterisation of a giant circular depression located inside the RGR central graben. The depression was discovered during multibeam prospection and surveyed with a Remotely Operated Vehicle, with rock sampling along a vertical transect. The depression is conical (350 m wide and 80 m deep) with walls of stratified, sub-horizontal, white fossiliferous wackestone, with incipient gravitational collapse. Lithological, mineralogical, and geochemical characterisation of the wackestone rule out methane in the formation of the depression. Based on geochemical data and on the finding of anhydrite III (forming at 110–300 °C), we propose a novel perspective on the formation of this kind of depressions, invoking hypogenic karstification and collapse, due to hydrothermal fluids along deep faults. Our geochemical approach complements previous geophysical observations of circular depressions at the RGR and contribute to the general understanding of the formation mechanisms of these intriguing seafloor features.

A new multi-analytical procedure for radiocarbon dating of historical mortars

The overarching challenge of this research is setting up a procedure to select the most appropriate fraction from complex, heterogeneous materials such as historic mortars in case of radiocarbon dating. At present, in the international community, there is not a unique and fully accepted way of mortar sample preparation to systematically obtain accurate results. With this contribution, we propose a strategy for selecting suitable mortar samples for radiocarbon dating of anthropogenic calcite in binder or lump. A four-step procedure is proposed: (I) good sampling strategies along with architectural and historical surveys; (II) mineralogical, petrographic, and chemical characterization of mortars to evaluate the feasibility of sample dating; (III) a non-destructive multi-analytical characterization of binder-rich portions to avoid geogenic calcite contamination; (IV) carbonate micro-sample preparation and accelerator mass spectrometer (AMS) measurements. The most innovative feature of the overall procedure relies on the fact that, in case of positive validation in step III, exactly the same material is treated and measured in step IV. The paper aims to apply this procedure to the ancient mortar of the Florentine historical building (Trebbio Castle), selecting micro-samples suitable for dating in natural hydraulic mortars. The discussion of the mortar dating results with the historical-archaeological hypotheses provided significant insights into the construction history of the building.

Using crushed stone dust as a substitute for fine aggregates in concrete

Generation of waste from mining and high consumption of natural aggregates resulting from civil construction works have significant economic and environmental impacts. Aiming to use the stone dust residue from the rock crushing process, this study experimentally evaluates the use of crushed stone dust as a partial substitute for fine aggregates in concrete with a compressive strength of 30 MPa, thus providing an alternative in civil construction activities. Crushed stone dust was evaluated through physical, chemical, mineralogical, petrographic, and micromorphological characterization tests. The characterization results indicated that the material is classified as medium and fine sand, with 68.2% silicon dioxide and quartz peaks, i.e., similar to natural sand. Axial compression tests were performed on twenty cylindrical specimens with diameters of 100 mm and heights of 200 mm, broken at 28 days. Five of such specimens were made of reference concrete, without stone dust, while fifteen contained concretes with stone dust. In this approach, the percentage of stone dust in the concrete specimens ranged between 20%, 50%, and 100%, and compressive strength was kept constant at 30 MPa, with five cylinders with stone dust for each percentage of sand replacement. The results show the contribution of stone dust to the mechanical behavior of the concrete specimens, which corroborate the possibility of applying it as a substitute for fine aggregates, as compressive strength was higher in the concrete specimens with 20% and 50% stone dust compared to the reference concrete.

Mineralogical Characterization and Geochemical Signatures of Supergene Kaolinitic Clay Deposits: Insight of Ropp Complex Kaolins, Northcentral Nigeria

This study presents the chemical and mineralogical composition of clay deposits and associated rock types within the Ropp Complex in order to assess the influence of parent lithology on the kaolinization, genesis, and utility of the deposit. Representative kaolin samples from E horizons of the weathering profiles and their bedrocks were collected from six sites in the Ropp Complex. Clay mineralogy was determined via the XRD technique, while a geochemical analysis was conducted using XRF, SEM coupled with EDS, and ICP-MS. The results showed that all kaolins dominantly contain kaolinite with a content of 77%–98% except for the AS1 kaolin with only minor kaolinite (20%) but mainly illite (65%). The notably lower crystallinity of kaolinite (HI value of 0.53–1.1) as well as its markedly small grain size is consistent with the formation of kaolinite from intensive chemical weathering of igneous rocks. The AS1 kaolin was probably formed from hydrothermal alteration in the burial stage due to the heating of groundwater by the late volcanism. Mobile trace elements (Sr, Ba, and Eu) exhibited a depletion trend, while immobile elements (Hf, Ta, Th) showed enrichment. The relatively more zirconium in kaolins implies the formation of low-temperature kaolinization. The notably high kaolinite content, accompanied by reasonable levels of Fe2O3 and TiO2, signifies a medium-grade quality. Furthermore, chondrite-normalized rare earth element (REE) patterns exhibit congruent trends in rocks and kaolin samples, indicating a relative enrichment in light rare earth elements (LREEs) alongside a discernible negative Eu anomaly. The abundant kaolinite and silicon–aluminum composition make the kaolins suitable for refractories, pharmaceutics, cosmetics, and supplementary cementitious material (SCM).

The formation of tubular seep carbonate deciphered from mineralogical and geochemical characteristics: an example from the South China Sea

As a special type of seep carbonate, the many details concerning the formation mode and mechanism of tubular seep carbonates are rarely reported. Here, new geochemical and mineralogical data regarding tubular seep carbonate (SQW-65) are reported. Sample SQW-65 had anomalously negative δ13C values and positive δ18O values, which suggested the dissociation of gas hydrate. Additionally, almost all the sub-samples showed no Ce anomaly (Ce/Ce*average = 0.93), with obvious U enrichment (21.3< UEF <240.3), which indicates that the studied tubular seep carbonate was formed in an anoxic environment. Subsequently, the formation process of the studied tubular seep carbonate is further discussed according to the variability of mineralogical and geochemical characteristics from the rim to the core of the tubular formation. In the early stage of the studied tubular seep carbonate (periphery), owing to the influence of terrigenous components, the quartz and Ti content and Y/Ho ratio were high. However, with the formation of the periphery, the influence of terrigenous components was gradually weakened. In addition, from the rim to the core, the carbon and oxygen isotope values showed a “covariation” coupling relationship, an enrichment of U, and a reduction in total rare earth element content. This is because as the outer wall thickens and the internal fluid channel narrows, the intensity of the sulphate-driven anaerobic oxidation of methane and the associated precipitation rate of carbonate also increase.

Hydrothermal alteration and elemental mass balance for the Surda Copper Deposit, Singhbhum Shear Zone, Eastern India: implications for both copper and magnetite–apatite mineralization

This paper explores the geological relationships, mineralogical and geochemical characteristics, and quantitative elemental mass balance constraints of the hydrothermal alteration zones within the uraniferous Surda copper deposit in the Singhbhum Shear Zone in eastern India, which is affiliated with an iron oxide–copper–gold system. Five distinct alteration zones are identified: a proximal potassic (biotitization) zone containing magnetite–apatite; a central chloritization zone containing copper, uranium, gold and magnetite; distal silicification (quartz) and albitization zones; and a transitional chlorite–sericitization zone. Evidence suggests these zones originated from mafic precursors linked to a subduction zone. Magnetite mineralization shows both magmatic ( δ 18 O + 2.0 to +4.8‰) and hydrothermal ( δ 18 O + 0.4 to +0.6‰) signatures. Hydrothermal magnetite–apatite formed at temperatures of 440 to 550°C, with continued crystallization at lower temperatures (280 to 360°C) concurrent with copper sulfide and uranium precipitation from an Fe-rich, isotopically heavy fluid ( δ 34 S + 4.55 to +9.66‰). Major elements (Ca, Na, Mg) and some minor and rare earth elements decrease from weakly altered mafic rocks to late alteration zones, reflecting the breakdown of Ca-bearing hornblende, biotite and plagioclase. Potassium decreases from early to late alteration zones due to mineral transformations. Mass-balanced geochemical data align with hydrothermal alteration mineral assemblages, indicating processes such as mineral dissolution, element absorption and sulfide behaviour. Overall, the study highlights the complex hydrothermal alteration processes shaping the Surda copper deposit and provides insights into ore formation mechanisms.

Use of the organic fraction from recycled alkaline batteries in the manufacture of LECAs: Experimental and Environmental Assessment

The industrial alkaline battery recycling process produces an organic fraction (OF) consisting of waste paper, plastic and cardboard. Currently, this OF is used for energy recovery, given the absence of a successful alternative recycling approach, attributed to its contamination and limited economic value. This study explored the valorisation of the organic fraction derived from the recycling of alkaline batteries as a foaming agent in the production of lightweight expanded clay aggregates (LECAs). The OF, was mixed with red stoneware atomized paste (RSAP) in varying proportions (5–30 wt%) and fired at temperatures between 1000 and 1200 °C. The volumetric expansion, density, and compressive strength of the resulting aggregates were determined via mineralogical and microstructural characterization. The results indicate the organic fraction's suitability as an expansion agent, particularly at 1200 °C with 5–15 wt% inclusion, showcasing density (0.65–0.75 g/cm3) and compressive strength (1.34–1.39 MPa) comparable to commercial expanded clays. The microstructural analysis revealed the formation of rounded pores, influenced by the firing temperature and OF content. A Life Cycle Assessment (LCA) compared the environmental impacts of this process with traditional LECA manufacturing, highlighting the potential environmental benefits of using recycled battery waste. This study marks the first incorporation of this battery waste residue into LECA manufacturing, providing valuable insights into its environmental implications and paving the way for sustainable waste management practices.

Microbial and hydrothermal dolomite formation in Early Cretaceous lacustrine sediments in Yin'e Basin: Insights from petrology and geochemistry

Dolomite is widely present in geological history, but its origin has always been a prominent problem that troubles sedimentologists. For lacustrine dolomite, current research has not yet provided a reliable explanation for its complex genesis mechanism. The Early Cretaceous lakes in Northwest China host various morphological dolomites, providing valuable materials for exploring the origin of dolomites. According to their petrological and mineralogical characteristics, it can be divided into thick laminated dolomite, thin laminated dolomite, dolomitic mudstone, and vein dolomite. The ratios of trace elements and rare earth elements show that these dolomites precipitated in a brackish–suboxic environment. The high δ13C values (>8 ‰VPDB) of thick laminated dolomite and some thin laminated dolomite suggest the involvement of methane-producing microorganisms in the precipitation of dolomite, and the appearance of microscale/nanoscale spherical dolomite aggregates and the dispersed organic matter around dolomite particles jointly confirm that microbial-mediated biological activity promotes dolomite precipitation. The dolomite stoichiometry (mole % MgCO3) confirms that thick laminated dolomite was deposited in a restricted shallow water environment, while dolomitic mudstone is mainly deposited in relatively open water areas. The thin laminated dolomite in the shale laminae represents short-term or seasonal climatic and environmental fluctuations. In addition, some carbonate minerals of dolomitic mudstone in shallow water environment recrystallized by post-depositional hydrothermal effect, resulting in δ18O value decreased (<−10 ‰VPDB). The vein dolomite is characterized by high rare earth content and low δ13C and δ18O values, and its Sr isotope (0.712894 ± 0.000374) values reflect that the hydrothermal fluid may have been formed by the mixing of infiltrating lake water and crustal magmatic water. According to the characteristics of fluid inclusions, it is inferred that the hydrothermal fluid has the characteristics of low temperature (108.3 °C–159.8 °C), medium salinity (3.5 wt%–14.3 wt% NaCl) and high density (0.95–1.00 g/cm3). The microbial mediation and tectonic hydrothermal fluids play an important role in the formation of the Early Cretaceous lacustrine dolomite.