The 14 elements from La to Lu (except the unstable Pm) form a group with similar chemical characteristics provided by their electronic configurations. Widespread, albeit in low abundance (hence their original description as ‘rare’), they were soon viewed as an opportunity to trace rock origins and geological processes. In addition to this scientific use, their technological applications have increased over the decades, which have multiplied in the present electronic age. Their exponential growth in demand and limited abundance have transformed them into strategic resources. Characteristic of clay minerals, which take centre stage in so many industrial applications and scientific issues, they have been discovered to be involved in this story as important commercial rare earth element (REE) deposits. This review describes how phyllosilicates bind REE, how environmental conditions modify REE contents in phyllosilicates and how such interactions can be used to trace both original rocks and the nature of modifying geological processes. Phyllosilicates bind REE strongly and concentrate them as adsorbed species in inner and outer poly-coordination complexes. This mode of binding controls the capacity for REE retention by phyllosilicates in conjunction with the physicochemical conditions of environmental fluids (salinity, pH, temperature, ligands, Eh) and fluid:rock ratios to determine the contribution of clay minerals to bulk REE signatures and their modifications in geological processes (soil formation, clay mineral precipitation from fluids, alteration, diagenesis, ore formation, transport).

Tetraphenylborate (TPB)-assisted exchange of Na+ for structural K was explored to establish the extent to which K and radiogenic Ar were removed from mixed-layer illite-smectite (Ilt-Sme) and detrital muscovite in various clay fractions (<1, 1–2 and 2–5 µm) of three Illinois Basin palaeosols and of Ilt-Sme from a K-bentonite (<2 µm) clay. The K–Ar age value of the treated Ilt-Sme was virtually the same as that of the untreated material regardless of TPB exchange duration in the K-bentonite. Interlayer K is extracted quickly but not completely from fine illitic material. Interlayer K is extracted more slowly but more completely from coarser clay-sized muscovite based on changes in X-ray diffraction traces, K contents and K–Ar age values of the palaeosol size fractions upon TPB treatment. One hour of TPB treatment revealed that (1) detrital Ilt-Sme was predominant over diagenetic Ilt-Sme in one palaeosol and (2) relatively more of the K in R0 Ilt-Sme is resistant to TPB treatment than in illite-rich, ordered Ilt-Sme, which indicates that the single illite layers hold K+ against TPB exchange in the fine Ilt-Sme. The age values of all palaeosol size fractions treated for several weeks converged into a narrow range (mean value 247 ± 5 Myr), consistent with the remaining K and Ar being predominantly in illitic interlayers of diagenetic origin. TPB treatment is a promising technique to isolate diagenetic (or pedogenic) illite in clay fractions containing detrital components for K–Ar age determinations.

In ion adsorption rare earth element (REE) deposits, REE are adsorbed onto clay minerals. Previous experimental studies indicate that adsorption depends on the chemical and physical properties of the clay and on the pH and salinity of the solution. This work presents adsorption experiments using two natural, purified kaolins with contrasting particle sizes exposed to different ligands at low and high ionic strengths (I) and at different pH levels to assess their influence on the adsorption of REE onto kaolinite. The results reveal that: (1) REE adsorption is rapid; (2) water/dilute nitric acid experiments gave optimum adsorption; (3) high-I NaCl, Na2SO4 and NaHCO3 demonstrated the least adsorption; (4) REE and yttrium are more adsorbed onto kaolinite in water/dilute nitric acid at lower pH, but adsorption is higher at higher pH when NaCl is present; (5) high I allowed less adsorption; and (6) scandium and thorium are more effectively adsorbed than REE and yttrium. The data suggest inhibition of adsorption by complex ion formation in solution at high I, and in the presence of strongly binding ligands (Cl–, SO42–, CO32–). Adsorption induces no REE fraction for low-I solutions in nitric acid, whereas enhanced chloride complex formation for light REE results in the preferential adsorption of heavy REE. sulphate inhibits adsorption, and carbonate at low I inhibits light REE adsorption relative to heavy REE, whereas at high I kaolinite may dissolve. Low-crystallinity, weathering-derived kaolinite demonstrates an order of magnitude more adsorption than processed, hydrothermal kaolin as a result of its increased surface area and adsorption sites.

Oil-based drilling fluids (OBDFs) are widely used in high-temperature ultra-deep wells, high-inclination wells, horizontal wells and various complex wellbores due to their excellent lubricity, high temperature stability, salt tolerance and contamination resistance. However, the intrusion of drill cuttings during drilling destabilizes water-in-oil (W/O) emulsion drilling fluids. Therefore, bentonite – a common component of drill cuttings – was selected to study the factors influencing its dispersion stability in W/O emulsions. The macroscopic stability of the system was evaluated via static observation, and the dispersion state was characterized using optical microscopy. Additionally, the viscosity, the contact angle of bentonite after adsorption of various surfactants, the interfacial tension and the charge of the bentonite particles were measured. The results indicate that various surfactants affect dispersion stability through distinct mechanisms. The system stabilized by a non-ionic surfactant exhibited low interfacial tension and the greatest stability. Furthermore, dispersion stability increased with surfactant concentration. Finally, binary surfactant systems were formulated with Span80. Calcium stearate demonstrated a significant synergistic effect with Span80, improving the stability of the bentonite dispersed in the emulsion, with an optimal ratio of 1:1. The mechanism of the stable dispersion of bentonite in oil was analysed, providing theoretical guidance for improving the stability of W/O emulsion drilling fluids during drilling operations.

Claystones and related sedimentary lithologies are considered as potential host rocks for the storage of high-level radioactive waste. The properties of claystones, which govern their barrier performance, can vary significantly between sites and formations. This study summarizes relevant barrier properties, with a particular emphasis on those dependent on burial history and maximum rock temperatures. Given the large number of properties influencing barrier quality, ranking them by relative importance is necessary. The predictable, non-linear behaviour of certain characteristics with geological burial depth allows for a substantial reduction in the number of properties requiring determination. Based on a set of representative repository-relevant rock lithologies, a case study comparison of potential claystone host rocks is presented. Hydraulic conductivity was assumed to be the most critical barrier property, with optimal values in rocks that reached peak diagenesis at burial depths exceeding 2000 m. To further distinguish claystone types and related lithologies in terms of barrier suitability, either cation-exchange capacity, reflecting the content of smectitic layers, or maximum temperature of palaeoburial heating (Tmaxgeo) can be used as an example. Pore-size distribution, correlating with the average particle distance, was particularly suited to estimating maximum burial depth, as it is less affected by thermal anomalies, pore fluid composition or cementation effects. Overall, combining key barrier properties with burial depth-dependent behaviour enables efficient assessment and comparison of claystone formations for deep high-level radioactive waste disposal. A quantitative comparison of various claystones, however, requires establishing a reactive solute transport model that simulates radionuclide release fluxes at specific timescales.

The precise characterization of the mesoporous mineral matrix of a geopolymer is greatly complicated by its amorphous nature. No conventional characterization technique allows for its direct investigation. We propose here the use of alternative current impedance spectroscopy (AC-IS; generally called ‘complex impedance spectroscopy’) as an indirect method for probing geopolymers via their ionic conduction properties. Our study of ∼50 K-geopolymer pellets using AC-IS has made it possible to better describe the mesoporosity of alkali-activated materials. The latter were prepared by partial substitution of metakaolin by argillite, and these were then subjected to heat treatment up to 900°C and exposed for a long time to high or low relative humidity. The metakaolin substitution rate along with post-synthesis temperature and storage conditions were the variables that allowed us to track the phenomenon of charge transport via mesoporosity. Refining the impedance spectra over a range of temperatures, using simple and robust models, provided a set of values for the activation energies and diffusion coefficients. The results confirmed the open and ‘through-hole’ nature of the porosity, the localization of K+ cations in the interstitial liquid and their diffusion through the amorphous ceramic matrix during heat treatment, as well as the possible resumption of long-term alkaline activation for poorly reactive aluminosilicate sources.

A multi-technique approach has been proposed to characterize weathering phases and their relationships with the primary rhyolitic paragenesis at Piloni di Torniella (Tuscany, Italy) hydrothermal kaolin mine. Analyses were carried out on geological samples and on material extracted from the mine for assessment of the ceramic application of the raw material. A multi-technique protocol was applied, involving both bulk techniques (e.g. X-ray powder diffraction) and microanalytical techniques (e.g. petrographic analysis, scanning electron microscopy with energy-dispersive spectrometry and micro-Raman spectroscopy), including imaging applications. Some secondary phases, such as alunite, halloysite and α-cristobalite, were identified and characterized. Highlighting the presence of such phases is important for the mine license holder and traders, who should manage the specific properties of the final commercial mine products for ceramic applications. Furthermore, a better understanding of the alteration mechanism of biotite at the study site was achieved; in fact, where the alteration process is complete, both kaolinite and halloysite have been identified as intergrown phases in biotite pseudomorphs. This suggests the presence of a lower-temperature fluid (<100°C) percolating in some areas of the mine, probably representing a different alteration stage than that which led to the kaolinization.

The reduction of volatile organic compounds (VOCs), especially the oxidation of highly toxic and chemically resistant toluene, remains a challenge in environmental catalysis. In this research, a porous TiO2/SiO2 support was initially fabricated through titanium pillaring of montmorillonite and then calcined and acid-leached as an efficient platform for Pt nanoparticle immobilization to yield Pt–TiO2/SiO2. The experimental data showed that the catalyst loaded with 0.37 wt.% Pt (0.37Pt–TiO2/SiO2) exhibits superior toluene oxidation performance, reaching a T90 of 190°C. Moreover, the catalyst exhibited remarkable water resistance, maintaining high efficiency even in the presence of 10% water vapour and outstanding long-term stability, with no substantial deactivation after 48 h of continuous operation. The performance improvement is explained by the high dispersion of Pt nanoparticles on the support and the metal–support interaction between Pt and TiO2, characterized by electron transfer from TiO2 to Pt. This interaction facilitates the adsorption and activation of reactant molecules. In situ diffuse reflectance Fourier-transform infrared spectroscopy explained the catalytic mechanism: toluene is sequentially transformed into benzyl alcohol, benzaldehyde and benzoate intermediates, which are subsequently converted to maleic anhydride by opening the ring and eventually mineralized into CO2 and H2O. This work developed a high-performance, durable catalyst using cost-effective and abundant natural minerals, offering promising prospects for practical abatement of industrial VOCs.

Kaolinite, a widely distributed clay mineral, is extensively applied in construction, industry and agriculture due to its physical, chemical and mechanical properties. This study employed quantum mechanics-based first-principles calculations to investigate the crystal structure, electronic properties and mechanical properties of kaolinite at various temperatures from a microscopic perspective. The main conclusions are as follows: structurally, lattice parameters (a, b, c) and volume increased with temperature, with c showing the largest such increase. The interlayer spacing between silicate tetrahedral and alumina octahedral layers slightly decreased from 0.3733 to 0.3702 Å, indicating that temperature exerts a stronger influence on the interlayer hydrogen bonds than on the covalent bonds within the layers. Electronically, in the 0–750 K range, kaolinite’s band gap narrowed from 5.13 to 5.06 eV; s orbital electrons of Al atoms jumped from the valence to the conduction band, reducing insulation. Mechanically, the elastic constants C11, C22, C33, C44 and C66 decreased while C55 increased with temperature. The bulk modulus declined continuously, whereas the shear modulus and Young’s modulus first increased then decreased. The universal anisotropy index decreased markedly, reducing elastic anisotropy. Temperature (0–750 K) significantly affects kaolinite’s properties. This study provides a reliable theoretical basis for optimizing the physicochemical and mechanical properties of kaolinite-based materials.

Natural zeolites modified with iron(II) ions or iron(III) phases represent two promising approaches for treating hexavalent chromium contamination in water due to their reduction and adsorption capacities, respectively. However, comprehensive comparative analysis of their efficiency remains limited. Fe(II)-modified zeolites can reduce Cr(VI) to the less toxic and insoluble Cr(III) form, while Fe(III)-modified zeolites primarily remove Cr(VI) through surface adsorption. This study evaluates the effectiveness of Fe(II)- and Fe(III)-modified zeolites using synthetic Cr solutions and real contaminated surface water. The materials were characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray fluorescence spectroscopy to assess their chemical, structural and morphological changes before and after chromium sorption. Batch and column tests determined Cr(VI) removal capacity, while Cr isotopes were used to track reduction reactions. The Fe(II) enrichment via cation exchange was highly effective. The Fe(II)-modified zeolite demonstrated a greater capacity for Cr(VI) removal from contaminated solutions, primarily through a reduction mechanism that converted Cr(VI) to Cr(III), as was confirmed by isotopic analysis. Its performance improved under higher-salinity conditions. However, it required prolonged contact time with the contaminant to achieve optimal efficiency. The Fe(III)-modified zeolite exhibited a heterogeneous distribution of iron oxide/hydroxide phases on its surface. This material showed some favourable characteristics in batch and column tests, including a notably faster Cr removal rate due to direct Cr(VI) sorption. However, it could only perform well when no other competitive ions were present in the solution, severely impacting its application in complex, real matrices.

Hydrogenation of CO2 into high-value carbon-containing compounds can effectively reduce greenhouse gas emissions. These plasma-catalysed systems offer convenient reactions under mild conditions, and, combined with their widely distributed, low-cost clay minerals, they can effectively reduce reaction costs and promote their further industrial application. However, research on their synergistic applications remains limited at present. In this work, we propose a model for synergistic catalytic CO2 conversion by coupling clay minerals and dielectric barrier discharge (DBD) plasma. The synergistic effects of eight typical clay minerals on CO2 conversion and CO selectivity catalysed by DBD and their influencing factors were explored through a combination of performance tests and characterization using X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy. Based on the performance and characterization results, minerals exhibiting a two-dimensional tubular structure, increased surface hydroxyl groups, appropriate transition metal active components and low water contents demonstrate greater CO2 conversion rates and CO selectivity. This work demonstrates that clay minerals can be used as effective DBD catalysts and represent low-cost green catalysts for the DBD catalytic system. This is of great significance for the rapid screening of clay minerals that are favourable for CO2 catalytic reactions and their further modification and application.

The accurate identification of clay minerals and associated phases remains challenging, particularly in fine-grained samples with complex assemblages. To assist in their identification, this study introduces MinMatch, a database and automated search program containing over 500 oxide compositions of clay minerals and their associated phases from soils, sediments and rocks. The program compares normalized oxide data with reference entries and ranks potential matches using Pearson correlation coefficients, supported by SiO2:Al2O3 ratios and additional statistical and graphical parameters. Its performance is demonstrated using mineral oxide datasets from well-characterized samples of the 12th Reynolds Cup competition, derived from coarse- and fine-grained separates analysed using energy-dispersive X-ray spectroscopy combined with scanning and transmission electron microscopy. The results show that MinMatch consistently ranks compositionally equivalent minerals among the top matches and successfully discriminates between closely related varieties. The approach provides a rapid, quantitative and reproducible tool for clay mineral studies, complementing X-ray diffraction and other analytical methods.

The circular recovery and reuse of nutrients from wastewater is vital for achieving sustainability goals and the European Green Deal objectives. This study investigates the selective recovery of ammonium (NH4+) using a zeolitic tuff rich in chabazite zeolite. We focused on targeting its applicability for farm-scale applications from different anaerobic digestates undergoing various pre-treatments (screw compression, microfiltration and centrifugation). The results were compared with a zeolitic tuff rich in phillipsite and chabazite from a previous study. The tested wastewaters included swine, cattle and municipal solid waste digestates. Adsorption isotherms and kinetics were evaluated, considering key factors such as initial NH4+ concentration, contact time, competing ions (e.g. K+), total solids content and pre-treatment strategies. The adsorption process followed the Freundlich model, indicating heterogeneous multilayer sorption, whereas the kinetic data aligned with pseudo-first-order and intraparticle diffusion models. NH4+ removal efficiency was inversely correlated with K+ levels and solids content, with livestock-derived digestates enabling the greatest nitrogen recovery per gram of zeolitic tuff due to their favourable composition and kinetics. Among the tested pre-treatments, centrifugation proved most effective, improving active site accessibility. A preliminary field-scale trial using microfiltered swine digestate at a 3% solid-to-liquid ratio demonstrated the feasibility of batch operation, with an estimated nitrogen recovery of 715 kg N year–1. This work lays the foundation for future comparisons with other zeolitic tuffs, such as those rich in clinoptilolite, and it supports the principle of nutrient circularity in agriculture by reducing reliance on synthetic fertilizers.

This work studies the hydrothermal synthesis of zeolitic materials from three types of industrial waste (granite cutting sludge; slate cutting sludge and aggregate washing sludge), which are regarded as low-cost materials. The synthesis was carried out through acid pretreatment with aqua regia to minimize iron content, followed by alkaline melting at 600°C followed by a hydrothermal crystallization stage at 180°C for 12 h. Characterization of the three synthesized zeolite materials by X-ray fluorescence, X-ray diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy with energy-dispersive X-ray spectroscopy confirmed that the methodology used induced the formation of LOS (Losod) zeolite (Na12Al12Si12O48·xH2O) as the predominant phase in all products, regardless of the waste used as the raw material. The end-products have a significant amorphous fraction (33–43 wt.%) and a zeolitic crystalline fraction (51–66 wt.%) and are enriched in Na and Al, and they have Si/Al and Na/Al ratios ranging from 1.27 to 1.39 and from 0.58 to 1.05, respectively, characteristic of low-silica zeolites. The synthetic zeolites showed reduced CO2 adsorption capacities at room temperature (0.50–0.55 mmol g–1) compared to commercial zeolites such as 13X (3.45 mmol g–1).

Engineering muck (EM) is an underutilized construction waste rich in clay minerals. The mechanical properties, composition, microstructures and reaction mechanisms of various EM-based geopolymers produced via acid or alkali activation are comprehensively compared and discussed in this study. The results indicate that EM mainly contains clay minerals (kaolinite, halloysite and dioctahedral mica), feldspar and quartz. The geopolymerization reactivity of EM was improved following crushing and calcination pretreatments, which destroyed the microstructure of the clay minerals and formed a reactive amorphous phase. Acid activation of calcined EM (EM700°C) resulted in greater geopolymerization reactivity than alkali activation. The highest 7 and 28 day compressive strengths of phosphoric acid-activated EM-based geopolymers reached 27.31 and 24.37 MPa, respectively, under a water/binder mass ratio of 0.7 and an Al/P molar ratio of 0.9. Comparatively, the maximum 7 and 28 day compressive strengths of alkali-activated EM-based geopolymers were only 7.82 and 11.66 MPa, respectively, under a water/binder mass ratio of 0.6 and a SiO2/Na2O molar ratio of 1.75. For phosphoric acid activation, reactive Al3+ mainly from calcined clay (e.g. metakaolinite) in EM700°C geopolymerized with PO43– and silica, forming phosphate-containing phases and amorphous silico-aluminophosphate (SAP; Si–O–Al–O–P) gels. In contrast, reactive SiO2 and Al2O3 from EM700°C participated in the geopolymerization process in alkaline solution, forming sodium aluminosilicate hydrate (N–A–S–H) gels and the byproduct faujasite. The geopolymerization reactivity of EM700°C and the resulting composition variations in various solutions contributed to the differences in the compressive strengths of EM-based geopolymers. This study provides a theoretical basis for preparing acid/alkali-activated geopolymers from EM.

Santa Maria Island (Azores, Portugal) hosts diverse clayey materials derived from the intense weathering of basaltic–andesitic volcanic units, volcaniclastic deposits and localized Miocene marine sediments. This study provides a preliminary characterization of 20 clay samples to assess their suitability for ceramics. Textural analyses revealed a clay fraction often of >70%, indicating advanced alteration, and a particle-size distribution favourable for ceramic processing. The clayey materials are dominated by total phyllosilicates, with kaolinite prevailing, along with minor quartz, Fe- and Ti-oxides and scarce feldspars as accessory phases. The materials are characterized by high Al2O3 and Fe2O3 contents and low CaO–Na2O contents, with Chemical Index of Alteration values of 88–98%, consistent with intense leaching under humid weathering conditions. Technological tests revealed low to moderate cation-exchange capacities in kaolinite-rich samples and greater values in smectitic and palygorskitic clays. Abrasivity is variable, controlled by the quartz content, microstructure and grain angularity, while density remained within expected ranges. According to their consistency, most samples are projected within the medium- to high-plasticity field, compatible with requirements for structural ceramics, with plastic index/liquid limit ratios comparable to successful red ceramic formulations. Rheological measurements showed predominantly shear-thinning behaviour, ranging from nearly Newtonian kaolinitic suspensions to highly pseudoplastic smectitic gels, suggesting that blending strategies may be necessary. The SiO2–Al2O3–total flux ternary diagram indicated that most samples fall within compositional domains comparable to those of widely used ceramic clay bodies, with a subset shifted towards greater total flux contents. The Santa Maria Island clays constitute a robust and versatile clay resource base suitable for red structural ceramics and, in specific cases, showing technological compatibility with healing clay/peloid-type applications.

Our energy needs must be met by envssironmentally friendly energy sources such as hydrogen energy because fossil fuels are being depleted and are restricted by CO2 emissions. One way to safely store hydrogen is to use porous materials, such as clinoptilolite (CLN), for physical adsorption. In this study, the effect of cation exchange with Ag+ on the hydrogen adsorption properties of Gördes CLN was investigated. The Ag-modified forms were obtained by treating the CLN with 0.01, 0.03, 0.05, 0.15 and 0.30 M AgNO3 solutions at 90°C for 5 h. The mineralogical and textural properties of the raw and Ag-treated CLNs were investigated using X-ray diffraction, X-ray fluorescence and nitrogen gas adsorption analysis. The specific surface area and microporous area values of the Ag-exchanged samples were slightly lower than those of raw CLN. The H2 adsorption capacities of the Ag-modified forms, measured at 77 K, decreased with increasing AgNO3 molarity after reaching an optimal threshold value of 0.01 M. The H2 uptake values ranged between 0.317 and 1.056 mmol g–1. The results of the study are explained as depending on the molarity of the AgNO3 solution used for cation exchange.

The clayey sludge resulting from aggregate washing in quarries of the Marrakech region generates significant environmental impacts and adds an economic burden to the industry. This study aims to characterize these clayey sludges in order to explore their potential for ceramic applications. Fifteen samples were collected from various quarries along the major waterways of the Marrakech region. The physical properties of the clayey materials were analysed according to particle-size distribution and plasticity limits. The mineralogical composition was determined using X-ray diffraction and Fourier-transform infrared spectroscopy. The chemical composition was determined using X-ray fluorescence spectroscopy. The carbonate and volatile contents were determined by calcimetry and loss on ignition at 500°C and 950°C, respectively. SiO2 and Al2O3 are main constituents, while quartz, feldspars and clay minerals are the main phases, along with minor calcite and hematite. Illite is the dominant clay mineral, followed by kaolinite and chlorite. The clayey material exhibits low to medium plasticity and variable particle-size distributions. The chemical composition of these sludges confirms their potential for red ceramic applications. However, their low plasticity, variable particle-size distribution and mineralogical composition, characterized by a low clay mineral content, limit their direct applicability. To improve their suitability for ceramic production, adding clay-rich tempers is essential to enhancing their mineralogical composition, granulometry and plasticity. Furthermore, the results provide a valuable guide for selecting local materials for Marrakech pottery and can serve as a model for other regions.

This study investigates the potential of six illite-rich clay samples from the Lower Cretaceous outcrops of Zemlet El Beidha (southern Tunisia) as precursors for geopolymer synthesis. Τhe raw materials are predominantly illitic, although kaolinite remains a main reactive phase. Samples BHG2 and BHG5 were specifically selected for further investigation due to their relatively high kaolinite content compared to the remaining samples and due to their distinct secondary mineralogy, with BHG2 being rich in hematite and BHG5 being rich in calcite. This selection allowed for a comparative analysis of how different impurities affect geopolymerization. The samples were calcined at 550°C, 750°C and 950°C to determine the optimal dehydroxylation temperature. Alkali activation was systematically performed using 10, 12 and 14 M NaOH solutions to assess the influence of alkalinity on the polycondensation process. The 12 M NaOH was most effective for the dissolution of aluminosilicate phases without the detrimental effects of excess sodium. Structural characterization (X-ray diffraction, Fourier-transform infrared spectroscopy and scanning electron microscopy) confirmed that the greatest compressive strength (∼8 MPa) was achieved with BHG5 calcined at 750°C. Although this strength is lower than that of kaolinite-based geopolymers, it meets the requirements for non-structural applications, such as thermal insulation or lightweight masonry units. This research demonstrates a viable pathway for valorizing abundant illitic-kaolinitic Tunisian clays into sustainable construction materials.

Clay minerals in the Yishu fault zone, as typical products of hydrothermal activity, carry critical information regarding subsurface geothermal processes. To clarify their hyperspectral remote sensing characteristics and their guiding value for geothermal resource exploration, this study takes the Yishu fault zone and three key subareas (Tangtou, Tongjing and Fangzi) as the research objects. Based on ZY1-02D hyperspectral remote sensing data, combined with principal component analysis and the Crósta method, we analysed the spectral features of typical clay minerals (illite, montmorillonite and chlorite) and extracted their spatial distribution patterns. In addition, ZY1-02E thermal infrared data were used to invert the land surface temperature so as to explore the spatial correlation between clay mineral distribution and geothermal anomalies. The results show that the spatial distribution of clay minerals is closely associated with fault structures, being mainly concentrated along the four major fault belts of the Yishu fault zone and their surrounding areas. High-intensity hydrothermal alteration zones dominated by clay minerals exhibit significant spatial overlap with surface temperature anomalies. The consistent distribution of clay minerals and known geothermal fields further confirms that the hyperspectral characteristics of clay minerals can effectively indicate the upwelling channels and accumulation zones of geothermal fluids. This study provides a rapid and accurate technical method for geothermal resource prospecting in the Yishu fault zone and other tectonically similar regions.