Mineralogical Characteristics Research Articles

Mud Spectral Characteristics from the Lusi Eruption, East Java, Indonesia Using Satellite Hyperspectral Data

Imaging spectroscopy allows us to identify surface materials by analyzing the spectra resulting from the light–material interaction. In this preliminary study, we analyze a pair of hyperspectral cubes acquired by PRISMA (on 20 April 2021) and EO1- Hyperion (on 4 July 2015) over the Indonesian Lusi mud eruption. We show the potential suitability of using the two sensors for characterizing the mineralogical features in demanding “wet and muddy” environments such as Lusi. We use spectral library reflectance spectra like Illite Chlorite from the USGS spectral library, which are known to be associated with Lusi volcanic products, to identify minerals. In addition, we have measured the reflectance spectra and composition of Lusi sampled mud collected in November 2014. Finally, we compare them with reflectance spectra from EO1-Hyperion and PRISMA. The use of hyperspectral sensors at improved SNR, such as PRISMA, has shown the potential to determine the mineral composition of Lusi PRISMA data, which allowed the distinction of areas with different turbidities as well. Artifacts in the VNIR spectral region of the L2 PRISMA reflectance product were found, suggesting that future work needs to take into account an independent atmospheric correction rather than using the L2D PRISMA product.

Geochemical and mineralogical features as indicators of sulfate-methane transition zones in shallow gas-bearing offshore sediments from Zhoushan

Subsurface shallow gas, primarily composed of biogenic methane (>95%), is highly-enriched in global offshore sediments. The redox conditions of methane-rich pore fluid play a crucial role in shaping the geochemical signatures associated with the anaerobic oxidation of methane (AOM) and vertical displacement of sulfate-methane transition zones (SMTZs) within deep sedimentary records. However, long-period, and continuous records of AOM and SMTZs in shallow gas-bearing offshore sediments are sparse. Here, we employed a comprehensive analyses of iron sulfide, elemental, and stable isotopies on a 63-m drilled sediment core (JC-1) from offshore Zhoushan. Four different layers U1−U4 were identified in 11.5−24 mbsf, 24−42 mbsf, 42−51 mbsf, and 51−63 mbsf, respectively, as revealed by the lithofacies and sedimentary structures. By comparing the pyrite contents, total sulfur to total organic carbon ratios, and δ34S-chromium-reducible sulfur values, the commonly seen organoclastic sulfate reduction occurred in U1 and U2, whereas significant AOM activities were found in U1 and U4. Further, the peaks of total sulfur to total organic carbon ratios, sulfur contents, and multiple positive δ34S-chromium-reducible sulfur values indicated the presence of AOM in SMTZs at 18.3, 52, and 59 mbsf. These intervals were featured by a sub-oxic or anoxic condition with strong methane seepages, evident from the scarcity of metals and the enrichment of Mo/Al and U/Al ratios. The presence of multiple SMTZs was consistent with the pore-water data of the adjacent YS4 and YS7 cores. In light of these findings, it is prudent to exercise caution when utilizing geochemical indicators, such as trace element proxies and the δ34S values of sulfide minerals, to comprehend the progression of fluctuating depositional settings in reaction to sea-level fluctuations and shallow gas reservoirs. This study provides a new perspective to better understand the evolution of unsteady depositional environments in response to sea-level changes and shallow gas reservoirs.

Mineralogy and Geochemistry Characteristics of Tanjero Formation in Selected Locations, Northeast of Iraq

Tanjero Formation (belongs to the upper cretaceous sequences( which are exposed in the northeast part of Iraq within the high folded zone. In this study, the mineralogy and geochemistry of the formation are examined by XRD and XRF techniques. The mineralogical study reveals that Calcite is the main mineral making the carbonate rocks of the formation with subordinate minerals of quartz and a low quantity of clay minerals (Chlorite, montmorillonite, and illite). Geochemical results revealed high levels of silica and calcium, aluminum, magnesium, and iron oxides. High concentrations of some trace elements (Cr, V) reflect their origin of basic and ultrabasic igneous rocks. The high content of Mn in the carbonate rocks of the formation reflects the depositional environment which is a deep marine environment. Most trace elements in the present study have positive correlations with SiO2, Al2O3, and K2O suggesting their association with clay minerals.

Mineralogical Characterization of Raw Clay from Rujište (Serbia) Used in Traditional Pottery Manufacture

The pottery produced from the Rujište deposit in Serbia has been protected under the guidance of UNESCO and the Sector for Intangible Cultural Heritage of Serbia since 2019. A study was conducted to evaluate the mineralogical characteristics of the raw clay from this deposit. This study used various techniques, such as X-ray diffraction (XRD), infrared (IR) spectroscopy, X-ray fluorescence (XRF), and differential thermal analysis (DTA) to characterize the clay. This study found that the clay contained mostly clay minerals (56.3%–41.9%), with illite, smectite, and chlorite as the predominant phases. Other phases identified were quartz, feldspars, carbonates, and iron-bearing minerals (43.8%–58.1%). The chemical analyses revealed a high abundance of silica (>52 wt.%) and alumina (~16 wt.%), with Fe2O3 (~6 wt.%), K2O (~2.8 wt.%), and a similar content of MgO as the main constituents. The physical features that were investigated included the granulometry (clay: ~31%–44%, silt: ~ 26%–23%, and sand: ~ 42%–32%), specific surface area (97 to 107 m2 g−1), cation exchange capacity (12.5–13.7 mmol 100 g−1), and color (yellowish to moderate brown). The preliminary results suggest that most of the raw clay from the Rujište deposit might be suitable for use in traditional pottery manufacture.

Characterization and concentration of U, Nb, Pb, Ag, and Fe from the Huayangchuan polymetallic ore

The separation and recovery of valuable metals from the Huayangchuan uranium polymetallic ore was investigated based on mineralogical research and mineral processing experiments. The most promising valuable elements in the ore, according to mineralogical studies, are U, Nb, and Pb. 95.75% of U and 93.00% of Nb are found in betafite, 46.85% of Pb is present in galena, 52.01% of Pb occurs in cerussite, and associated Ag exists primarily in galena. The beneficiation process involving gravity concentration, magnetic separation, and flotation was determined based on the mineralogical characteristics of the ore. The U-Nb concentrate with U grade of 3578 ppm and recovery of 83.18 %, Nb<sub>2</sub>O<sub>5</sub> grade of 4391 ppm and recovery of 74.55 % can be obtained, and five elements including U, Nb, Pb, Ag, and Fe are recovered. Compared with the previous beneficiation experimental process, the flowsheet is greatly simplified and the beneficiation recovery efficiency has been improved. The results of this investigation can help to address the gaps in the processing of low-grade uranium deposits with similar mineralogical properties.

Integrated approach to sustainable utilization of phosphate waste rock in road embankments: Experimental insights, stability analysis, and preliminary economic evaluation

This paper highlights an issue that has not received much attention which is the use of phosphate waste rock (PWR) in road embankments. This study focuses on the valorization of marly clay and marly limestone lithologies, which are abundant but often unused or undervalued, being simply deposited around mine sites. Investigating the potential use of these materials in road embankments requires a combination of experimentation, stability analysis, and economic evaluation. The materials were collected from mining trenches in the Benguerir mine (Morocco). The samples were subjected to i) chemical and mineralogical characterization; ii) environmental characterization; and iii) geotechnical characterization. The results of the characterization show that the samples are chemically dominated by CaO (12–33 wt%), SiO2 (23–38 wt%), and MgO (7 – 9 wt%); mineralogically, the main phases are quartz, calcite, dolomite, apatite, and clay minerals. The environmental characterization classified the studied materials as non-hazardous waste. In terms of geotechnical characterization, the marly limestone and marly clay belong to the A3 and R33 categories, which means that they can be successfully used as a sustainable alternative material for the embankment. This finding supports their safe utilization. The stability analysis reveals that embankments up to 10 m in height can be constructed with marly clay without significant physical instability risks. Satisfactory safety factors (SF) were found (SF=1.97 for H=5 m and SF=1.54 for H=10 m). For marly limestone, the height limit is less than 10 m (SF=1.74 for H=5 m and SF=1.33 for H=10 m), but it can be increased to 10 m by adding a bench of rock fill with a safety factor of 1.64. Finally, an economic evaluation demonstrates that PWR can be used as embankment materials within a radius of 28 km around the mine site. It appears to be a cost-effective alternative compared to conventional materials.

Integrated Remote Sensing for Geological and Mineralogical Mapping of Pb-Zn Deposits: A Case Study of Jbel Bou Dahar Region Using Multi-Sensor Imagery

This research applies remote sensing methodologies for the first time to comprehensively explore the geological and mineralogical characteristics of the Jbel Bou Dahar region. An integrated approach with multi-sensor satellite images, including ASTER, Landsat-8, and Sentinel-2 was applied with the aim to discriminate the different lithological units in the study area. We implemented a suite of well-established image processing techniques, including Band Ratios, Principal Component Analysis, and Spectral Angle Mapper, to successfully identify, classify, and map the spatial distribution of carbonate minerals, OH-bearing minerals, and iron oxide minerals. Due to its high spectral resolution in the short-wave infrared region (SWIR), the ASTER sensor provided the most accurate results for mapping carbonate and OH-bearing minerals compared to the Sentinel-2 and Landsat-8 sensors. Conversely, Sentinel-2 offers high spectral and spatial resolution in visible and near-infrared (VNIR) corresponding to the regions where iron oxide minerals exhibit their characteristic absorption peaks. The results confirm the advantages of remote sensing technologies in the geological and mineralogical exploration of the study area and the importance of selecting the appropriate sensors for specific mapping objectives.

An Archaeometric Study of the Iron Age Ceramics from Quinta do Almaraz Archaeologic Site (8th to 5th Centuries BC)—Colour and Mineralogical Characterization

The ceramic pastes of ca. 31 samples recovered from the Almaraz archaeological site, located in the south bench of Tagus River, were studied in detail using XRF, micro-Raman and GSDR spectroscopies, as well as the XRD technique. The ceramic sherds could be grouped into six categories, red slip tableware, decorated tableware, yellow slip tableware, grey tableware, common tableware, and handmade pottery. Our studies of the mineralogic composition of the sherds’ body indicate all ceramics were produced locally, using siliceous clays in most cases and calcareous clays in a few ones. Micro-Raman and ground state diffuse reflectance absorption spectroscopy provided useful information regarding the materials used to produce the coloured ceramics: hematite and brookite for the red slip and decorated ceramics, jacobsite or carbon black for the black decoration or grey ceramics. For the yellow slip tableware, a simple engobe rich in yellow clay was used. XRF spectroscopic studies provided the elemental composition of all samples, and biplots of the potassium (K) versus calcium (Ca) contents, normalized to the silicon content of each ceramic paste, clearly show Pliocene and Miocene local clays sources were used to produce most ceramics. Only one sherd can be considered a Lisbon production.

Proximal sensors for modeling clay mineralogy and characterization of soil textural fractions developed from contrasting parent materials

Proximal sensors combined with X-ray diffraction (XRD) have optimized soil characterization, but scarce studies have focused on predicting the contents of minerals under this scope. The objectives herein were to: a) use the portable X-ray fluorescence (pXRF) spectrometry, diffuse reflectance spectroscopy in the range of visible and near-infrared (Vis-NIR), magnetic susceptibility (χ) and XRD to characterize the mineralogy of soils derived from representative Brazilian soil parent materials, and b) create models to quantify the minerals obtained via XRD. Twenty-two soil profiles developed from gabbro, gneiss, quartzite, mineral and organic sediments were described with 53 soil horizons sampled. Each sample had the sand, silt and clay fractions separated and analyzed with XRD, pXRF, χ, and Vis-NIR. Models were created using the Random Forest algorithm permuting the following predictor variables (separately and combined): pXRF, parent material (PM), χ, soil texture (sand, silt, and clay content), and Vis-NIR. Models’ accuracy was calculated using the leave-one-out cross-validation method. Si, Al, Fe, Ca, K, and Ti contents obtained by pXRF and the χ discriminated the soil particle size fractions according to the parent material. XRD analysis allowed the evaluation of the pedogenetic development of soils and their relation to the respective parent material. The best models for mineral contents were found for hematite (Hm) (104)+(Gt) (130) (R2 = 0.85), Hm (110) + Mh (131) (R2 = 0.76), kaolinite (Kt) (001) (R2 = 0.73), Kt (002) (R2 = 0.80), mica (Mc) (001) (R2 = 0.77), and Mc (020) + Kt (020) (R2 = 0.81). Clay mineralogy content was accurately modeled using only pXRF and parent material data. This approach can facilitate and speed up detailed soil mineralogy characterization. Further studies are encouraged to model the content of minerals found in the sand and silt fractions of soils with diverse mineralogy via proximal sensors and using larger data sets.

Pore heterogeneity analysis and control mechanisms in Cambrian shale of the Shuijingtuo Formation, Yichang area, China

This study focuses on understanding the fractal characteristics and controlling factors of micropore structures within organic-rich shale of the Cambrian Shuijingtuo Formation in the Yichang area of Hubei Province. Mineralogy, petrology, and organogeochemical characteristics were confirmed through comprehensive testing methods, including whole-rock X-ray diffraction and organic geochemical analyses. Additional experiments included low-temperature carbon dioxide adsorption, low-temperature nitrogen adsorption, and high-pressure mercury injection. Fractal dimensions of micropores, mesopores, and macropores were calculated using the V-S, FHH, and MENGER sponge models, respectively. Results indicate that the Cambrian Shuijingtuo Formation represents a typical deposit from an alkaline water body, resulting in high-calcareous shale. Fractal dimensions were as follows: micropores (D1) ranged from 2.1138 to 2.3475 (average 2.2342), mesopores (D2) ranged from 2.5327 to 2.7162 (average 2.6171), and macropores (D3) ranged from 2.7361 to 2.9316 (average 2.82905). Correlations were observed between total organic carbon (TOC) content and Ro with D1 and D2 (positive) and D3 (negative). Shale pore volume and specific surface area exhibited positive correlations with D1 and D2 but negative correlations with D3. High bio-deposited silica positively influenced micropore and mesopore development, while clay mineral compaction and dehydration transformations favored macropore development. Carbonate minerals primarily contributed to regular macropores, with complex correlations involving fractal dimensions D1, D2, and D3. The research results provide theoretical support for analyzing pore fractal characteristics of shallow old Marine shale reservoirs and the prediction and development plan of high-quality reservoirs of the Shuijingtuo Formation in the Yichang area.

In Situ Use of Mining Substrates for Wetland Construction: Results of a Pilot Experiment.

This paper evaluates an experimental wetland as part of a pilot soil reclamation project in a mining area. The wetland was constructed using materials of mining origin from the area; most reactive materials of acid pH were stabilised using limestone filler. The study selected macrophytes that are tolerant to potentially toxic elements (PTEs) and resistant to salinity, namely Phragmites australis, Juncus effusus, and Iris pseudacorus. These macrophytes were then placed in pots containing substrates composed of different mixtures of topsoil, peat, and mining waste (black or yellow sand). A thorough analysis of the physicochemical and mineralogical characteristics of the materials included studies of PTE mobilisation. This study emphasises the significance of the rhizosphere in directing the transfer of PTEs to the plant and the correlation between the substrate and the development of plant defence mechanisms, such as the formation of Fe-plates. Scanning electron microscopy was used to highlight these aspects and validate the results of the analytical determinations. These wetlands can be proposed as a phytoremediation strategy for areas affected by mining and maritime influence. They are easy to construct and remain stable, providing important ecosystem services such as the natural attenuation of acid mine drainage, support for vegetation development and fauna, and a clean ecosystem.

Ore/waste identification in underground mining through geochemical calibration of drilling data using machine learning techniques

Chemical X-ray fluorescence (XRF) analyses of drill cuttings and measurement-while-drilling (MWD) records were jointly collected in two production levels with different mineralogical characteristics of a narrow vein underground mine. More than 840 chemical samples and 23,000 MWD records with geological and geotechnical accompanying data constitute the database used in this study. A classification methodology and a site-specific model were developed following two approaches: a k-means clustering heuristic algorithm to define rock classes based on their physicochemical features, and a machine learning (ML) ensemble model trained with those classes to distinguish ore and waste as function of drilling parameters. Oversampling and under sampling techniques are required due to the unbalanced size of the rock classes. The prediction success rate (F1 score) is about 70% for the ore when associated with a high content of silica, and about 86% for the waste. When continuous drilling chips sampling is carried out, the operator bias is reduced and the F1 scores exceed 80% for all classes using different ML techniques. The study presents a complete analysis of the correlations between rock mineralogical characteristics and their mechanical response during drilling, highlighting the benefits that MWD-based information can bring to the analysis-while-drilling (AWD) for ore grading.

Geochronology and geochemistry of zircon and columbite–tantalite group minerals from the Weilasituo Sn–polymetallic deposit, northeastern China: Implications for the relationship between mineralization and the magmatic–hydrothermal transition

The Weilasituo Sn–polymetallic deposit, located in the southern portion of the Great Xing'an Range of Inner Mongolia, China, is a super-large Sn deposit associated with abundant Li, Rb, Nb, Ta, Zn, and Cu resources. Despite that previous studies have characterized the age, hydrothermal evolution, and genetic relationship between the alkali feldspar granite porphyry and associated Sn–polymetallic mineralization, the magmatic–hydrothermal evolution and ore–forming processes remain ambiguous. To address these ambiguities and bridge this knowledge gap, this contribution characterizes the texture, geochemistry, and U–Pb isotope composition of zircon and columbite–tantalite group minerals (CGMs) from amazonitized alkali feldspar granite (AMG) and albitized alkali feldspar granite (ABG) in the Weilasituo deposit. Type-I zircon (Zr1) is inclusion-poor, translucent, and is characterized by low light rare earth element (LREE) contents, high (Sm/La)N ratios (mean = 655.7), and low Th/U (mean = 0.21 < 0.3), Zr/Hf (mean = 5.46), and Y/Ho ratios (mean = 4.42), indicating that it formed during the magmatic–hydrothermal transition. Type-II zircon (Zr2) is inclusion-rich, porous, has a low CL response, and is characterized by low Th/U ratios (0.08–0.32, mean = 0.17), high LREE contents, weakly positive Ce anomalies, and low (Sm/La)N ratios (mean = 20.7), indicating that it formed via hydrothermal alteration of Zr1 (i.e., magmatic–hydrothermal zircon). Type-I CGM (CGM1) generally lacks oscillatory zoning, and has similar and positively correlated Ta/(Nb + Ta) and Mn/(Mn + Fe) values (AMG: R2 = 0.93; ABG: R2 = 0.75), indicative of a magmatic origin. Type-II CGMs (CGM2) occur as rims on CGM1 and are characterized by higher Ta/(Nb + Ta) and lower Nb/Ta ratios than CGM1, indicative of precipitation from a hydrosilicate liquid during the magmatic–hydrothermal transition. Based on the characteristics of CGMs, two stages are evident in the evolution of the Weilasituo granite porphyry: an earlier magmatic differentiation stage and a later magmatic–hydrothermal transition stage. Furthermore, the magmatic–hydrothermal transition stage can be subdivided into the AMG and ABG substages within the porphyry system based on petrological and mineralogical characteristics. The U–Pb ages for zircons and CGMs from the alkali feldspar granite porphyry range from 137.2 ± 2.0 Ma to 129.8 ± 1.4 Ma, without a notable age gap. The similarity in U–Pb ages between CGM1–CGM2 and Zr1–Zr2 indicates that the magmatic stage and the magmatic–hydrothermal transition at Weilasituo were continuous processes that occurred during the Early Cretaceous.

Mineralogical Characteristics of Greywackes at Lake Bosomtwe Area in the Ashanti Region of Ghana

The mineralogical content and texture of greywackes in the Lake Bosomtwe area of Ghana’s Ashanti Region are examined in this petrographic study. The Graywackes are fine- to medium-grained, poorly sorted, firmly indurated sedimentary rocks. Quartz is the dominant framework component of the studied specimens, and it is both monocrystalline and polycrystalline. The average mineral compositions of the samples are quartz (53%), feldspar (16%), biotite (4%), opaque minerals (2%), and lithic fragments (1%) and classified as feldspathic wacke. The other predominant minerals include orthoclase and plagioclase feldspars. Other constituents include biotite, opaque minerals, and iron oxides. The characteristics of an advanced sedimentary environment with moderate mobility are evident in the rocks. The discoveries broaden our understanding of the Ashanti Region’s geology and have ramifications for resource development, environmental management, and geological study.

Preparation of Geopolymeric Materials from Industrial Kaolins, with Variable Kaolinite Content and Alkali Silicates Precursors.

In the present work, the development of geopolymeric materials with Na or K based on industrial kaolin samples, with variable kaolinite content and alkaline silicates, is studied. XRF, XRD, FTIR and SEM-EDS have been used as characterization techniques. Three ceramic kaolin samples, two from Algeria and one from Charente (France), have been considered. In particular, chemical and mineralogical characterization revealed elements distinct of Si and Al, and the content of pure kaolinite and secondary minerals. Metakaolinite was obtained by grinding and sieving raw kaolin at 80 μm and then by thermal activation at 750 °C for 1 h. This metakaolinite has been used as a base raw material to obtain geopolymers, using for this purpose different formulations of alkaline silicates with NaOH or KOH and variable Si/K molar ratios. The formation of geopolymeric materials by hydroxylation and polycondensation characterized with different Si/Al molar ratios, depending on the original metakaolinite content, has been demonstrated. Sodium carbonates have been detected by XRD and FTIR, and confirmed by SEM-EDS, in two of these geopolymer materials being products of NaOH carbonation.

Investigation on the properties of sustainable alkali-activated GGBS mortar with nano silica and dredged marine sand: Mechanical, microstructural and durability aspects

In recent years, alkali-activated mortar (AAM) has emerged as a promising alternative to ordinary Portland cement (OPC) due to concerns regarding the environmental impact resulting from cement production, which releases carbon dioxide and degrades the quality of the environment. To address these concerns, researchers have explored the addition of supplementary binder materials to enhance cement properties and mitigate pollution. The effectiveness of these binder materials depends heavily on their chemical composition and fineness. Notably, ground granulated blast furnace slag (GGBS) enhances the strength and durability of the cement. In response to the scarcity of river sand (RS), dredged marine sand (DMS) has gained popularity as a potential substitute within the civil engineering field. Furthermore, the integration of nanomaterials has shown promising improvements in the mechanical and microstructural properties of mortar. Therefore, this study aims to investigate the properties of mortar by incorporating nano silica (NS) within the range of 1% to 7%, varying the molarity from 2 M to 8 M, and substituting RS with DMS. The tests carried out encompass a range of evaluations, including compressive strength, flexural strength, SEM-EDS, XRD, UPV, RCPT, and carbonation analysis, to comprehensively assess the properties of the mortar. The study reveals that the AAM demonstrates optimal performance when 50% of RS is replaced by DMS in the absence of NS. Once this optimal point is determined, further analyses are conducted at this value while varying the concentrations of NS from 1–7%. The experimental results indicate that replacing 50% of RS with DMS and incorporating 6% NS leads to maximum compressive strength (49.2 MPa) and flexural strength (9.36 MPa) in the assessed properties. Furthermore, the incorporation of NS in GGBS-based AAM mixes enhances durability by improving resistance against chloride penetration, reducing water absorption, and minimizing carbonation diffusion. Additionally, the microstructural and mineralogical characterization of GGBS-NS-based AAM specimens demonstrates the formation of C-S-H and C-A-S-H gels as the end products of the reactions.

Synthesis of Eggshell Powder and GGBS Geopolymer Designed by the Taguchi Method

This research endeavors to develop a geopolymer mortar synthesized from eggshell powder and ground granulated blast-furnace slag, utilizing the Taguchi L25 optimization technique to refine the synthesis process across molarity (A), precursor ratio (B) and curing duration (C). Analyzed at five distinct levels across 25 experimental setups, denoted as A1B1C1 through A5B5C5, these variables were rigorously tested. Compressive-strength measurement was employed as a criterion to assess the performance of three samples from each setup, alongside setting-time evaluation to ascertain the geopolymer concrete's workability. Optimal results were observed with a 60% eggshell to 40% slag ratio (A5B1C5), yielding the highest average compressive strength of 49.5 MPa after a curing period of 56 days. Conversely, a mix comprising 100% eggshell (A2B5C1) manifested the lowest compressive strength of 5 MPa at a 3-day curing period. Taguchi's signal-to-noise ratio analysis pinpointed the precursor ratio as a crucial determinant of compressive strength. Additionally, setting-time investigations revealed A5B1C5 as exhibiting the most advantageous initial and final setting times of 15 minutes and 30 minutes, respectively, compared to the protracted durations of 240 minutes and 540 minutes for A2B5C1. Through comprehensive chemical, micro-structural and mineralogical characterizations via X-ray fluorescence, Scanning Electron Microscopy (SEM) and X-ray diffraction, it was found that an increased proportion of ground granulated blastfurnace slag relative to eggshell enhances surface smoothness and density, indicative of successful polymerization. This was further corroborated by X-ray diffraction, which confirmed the formation of sodium alumina-silicate hydrate, calcium aluminum silicate hydrate and calcium silicate hydrate gels. Consequently, the study substantiates the potential of employing eggshell powder and ground granulated blast-furnace slag in the sustainable fabrication of geopolymers from waste materials. Keywords: Geopolymers, GGBFS, Eggshell, Taguchi Method, Compressive strength

Characterisation of Adobe and Mud-Straw for the Restoration and Rehabilitation of Persian Historical Adobe Buildings.

In the restoration or rehabilitation of traditional buildings, compatible materials with known characteristics must be used. However, the existing literature lacks comprehensive studies on the characterisation of Persian mud-straw plaster, focusing primarily on Persian adobe. Moreover, previous research on Persian adobe has primarily employed XRF and XRD tests, neglecting ion chromatography, moisture sorption isotherm determination, and thermogravimetric analysis with differential scanning calorimetry. Consequently, there is a shortage of information regarding the elemental composition, mineralogical characteristics, moisture sorption behaviour, and thermal properties of Persian mud-straw plaster, as well as Persian adobe bricks. This paper aims to address this research gap by examining historical and new adobe bricks and mud-straw plaster used in Iran, utilising a comprehensive array of analytical techniques. The results from XRF analysis reveal relatively similar chemical compositions across all samples, while XRD analysis indicates predominantly similar mineral phases. Ion chromatography results demonstrate higher conductivity and chloride concentrations in the mud-straw samples than the adobe samples, with higher values for new samples than historical ones. Freshly used straw, clay, or soil may have higher chloride concentrations caused by the arid climate and soil salinisation in the area. Additionally, moisture sorption isotherm determination results show that adobe and mud-straw plaster with a higher salt load of chlorides have significantly higher moisture absorption. The increased straw quantity in the samples increases the moisture content. Furthermore, thermogravimetric analysis and differential scanning calorimetry indicate that, at low heating, adobe and mud-straw plaster lose water due to dehydration, and at high heating, they lose carbon dioxide due to decarboxylation. The comprehensive characterisation of Persian adobe and mud-straw plaster in this study fills a significant gap in the literature and offers invaluable insights for informing restoration and rehabilitation processes, ensuring the compatibility of the materials used.

Magmatic−hydrothermal evolutionary processes in highly evolved granitic systems: Insights from zircons of the Baishitouquan pluton, NW China

As a robust accessory mineral in igneous rocks, the mineralogical and geochemical characteristics of zircon can record the lithological differentiation and magmatic−hydrothermal evolution of highly evolved granitic systems. The F-Rb−rich, highly evolved Baishitouquan pluton of NW China exhibits gradual lithological changes from leucogranite, amazonite-bearing granite, and amazonite granite in the lower levels of the pluton to topaz-bearing amazonite granite, topaz albite granite, and pegmatite in the upper levels. In this study, three types of zircon grains were identified in five lithological zones based on textural and chemical characteristics. Type I zircon, which mostly occurs in leucogranite and amazonite-bearing granite, exhibits oscillatory zoning in cathodoluminescence images and experienced low degrees of radiation damage (0.21−0.68 × 1015 α-decay events/mg), which is indicative of its magmatic origin. Type II zircon, which mostly occurs in amazonite granite and amazonite pegmatite, exhibits textures that are indicative of hydrothermal alteration (e.g., spongy texture, porosity, and microcracks), and has elevated concentrations of some cations, such as Ca and Al. Type II zircon contains a higher concentration of non-formula elements, including rare earth elements (REEs), and Hf, Th, and U, than Type I and III zircons. Additionally, Type II zircon exhibits a significant M-type lanthanide tetrad effect and experienced varying levels of radiation damage (3.75−11.72 × 1015 α-decay events/mg). These characteristics suggest that Type II zircon has a hydrothermally altered origin. Type III zircon, which is restricted to the topaz-albite granite, has the smallest crystal size among all types of zircon grains, shows a euhedral to anhedral mottled appearance, and is characterized by patchy, cloudy, or irregular zoning, with numerous fluid inclusions. This type of zircon contains higher concentrations of Ti (110−1030 μg/g) than other types of zircon grains. Additionally, this type of zircon experienced limited radiation damage (2.18−3.69 × 1015 α-decay events/mg), and has a smooth surface and homogeneous internal textures. These characteristics suggest that Type III zircon is the product of fluid interaction with hydrothermally altered Type II zircon. Accordingly, this type of zircon crystallized directly from a Zr-saturated hydrothermal fluid during the later stages of magmatic−hydrothermal evolution. These contrasting textural and compositional features of the three types of zircon grains are indicative of three stages of magmatic−hydrothermal evolution of the Baishitouquan pluton: magmatic, magmatic−hydrothermal transition, and hydrothermal. These magmatic and hydrothermal processes were involved in the enrichment, transport, and precipitation of rare metals, such as Rb. Accordingly, this contribution demonstrates that the textures and chemistry of zircon grains can serve as petrogenetic indicators for assessing magmatic−hydrothermal evolution and rare-metal mineralization in highly evolved granitic systems. Furthermore, this study presents a model of the magmatic−hydrothermal evolution of F-rich, highly evolved granitic systems through the lens of zircon.

Managing Marble Quarry Waste: Opportunities and Challenges for Circular Economy Implementation

Marble has been a prominent natural stone exploited since ancient times, commonly employed as a building material and ornamental stone. However, the disposal of waste generated from marble extraction, particularly fine sludge, poses significant environmental challenges for the dimensional stone industry. The difficulty in managing and recovering these materials, exacerbated by local regulations and the absence of suitable recovery protocols, often leads to landfilling. This issue is exemplified by the Carrara Marble Basin in the Apuan Alps (Tuscany, Italy), where more than half of the extracted marble remains as quarry waste or debris. Modern cutting technologies have intensified the production of finer materials and sawing residue, known as “marmettola”, ranging in size from fine sand to silt. The disposal of these materials, commonly through landfilling or abandonment, has profound environmental repercussions. This research primarily aimed to carry out a preliminary physical, mineralogical, and morphological characterization of the fine waste and sludges generated from Carrara Marble exploitation. The findings reveal the high granulometric uniformity of the materials, and a nearly pure carbonate composition, suggesting potential for reuse in various industrial sectors such as paper, plastics, and pharmaceuticals production.