The Pleistocene sediment infill of elongated glacial incisions of the southern North Sea (SNS) is often referred to as tunnel valleys (TVs). The depositional environment is not yet fully understood and the present study addresses this challenge from the perspective of clay-mineral transformation (illite to illite-smectite) reported from the largest Elsterian TV of the SNS. Material acquired from the K14-12 borehole in the Dutch offshore was analyzed by X-ray diffraction (XRD), electron microscopy, electron microprobe, and laser particle-size analysis. Illite and illite-smectite (I-S) appeared as dominant clays along with minor amounts of kaolinite, kaolinite-smectite, and chlorite. The largest amount of I-S is recognized in the main TV portion, while in pre-glacial and uppermost deposits, I-S is less abundant. The XRD peak fitting and deconvolution suggest that I-S consists of several intermediates — ordered (well crystallized illite + R3 I-S) and disordered (R0 I-S + R0 I-SS). Given the average particle sizes (>2 µm) and Kübler index values (0.415–0.341°Δ2θ), illite as well as chlorite and kaolinite were interpreted as detrital. On the basis of the distinctive distribution, grain sizes, and compositional variations of I-S, formation by means of early diagenetic in situ smectitization of illite under a cold climate is proposed. The process operated via a series of mixed-layer intermediates derived from an illite component being converted progressively to low-charged smectite. The reaction is marked by a significant net loss of K and Al with replacement by Si in a tetrahedral coordination. Layer-charge imbalance is accommodated by Fe(III) and Mg entering an octahedral sheet, whereas Ca partly fills the interlayer sites. Smectitization rates were controlled by illite grain sizes. The results of the present study support strongly the existence of an ice-marginal freshwater depositional environment at the glacial maximum in the SNS in which early diagenesis at low temperatures resulted in incomplete conversion of illite to smectite.

This study reassesses an inscribed victory catalogue from Sinope (IK Sinope 105) that is often discussed in scholarship concerning agonistic culture in the Roman world. One particularly curious element of this inscription is the empty nature of the penultimate line, which bears only the numerals rho-nu. In the existing scholarship, this is usually interpreted as the sum of all the athlete’s victories. This paper challenges the orthodox interpretation, using a combination of David French’s squeezes housed at the British Institute at Ankara, supported by autopsy and recent photographs of the stone itself. It goes on to reconsider the practice of summing athletic victories in honorific inscriptions more generally, examining a specially compiled dossier of 207 inscriptions of comparable date to IK Sinope 105, and concluding that the practice was relatively rare. Finally, this paper considers other possible interpretations of the rho-nu in IK Sinope 105, among which is the suggestion that rho-nu could be a chronographic feature. While the interpretation of the rho-nu in IK Sinope 105 remains open, the combination of a close analysis of the stone with a wider contextual consideration of the genre demonstrates how much more remains to be said about even a well-known and often cited inscription.

Clays and clay minerals dissolve over a broad pH range, such as during sediment diagenesis and in a variety of applications, including nuclear waste storage, landfills, and geopolymer binders in the construction industry. The solubility depends on process parameters (pH, temperature, pressure, etc.) and material properties (phase content, clay mineral composition, particle size, etc.). Pretreatments such as calcination or severe grinding change the material properties and could enhance solubility, which is called activation. The aim of the current study was to determine the solubility of three different clay minerals after calcination (metakaolinite, metamontmorillonite, and metaillite) in high molar alkaline solutions (NaOH) up to 10.79 mol/L and pH = 14.73. Furthermore, the solubility of an Al(OH)3 powder in alkaline solution (NaOH) was analyzed, as it can be used to adjust the Si:Al ratio of geopolymer precursors. The residues of the clay minerals after the alkaline treatment were investigated to disclose potential alterations in their phase contents. Based on the results of the thermal and alkaline activation, conclusions about the suitability as geopolymer precursors were made. All clay minerals showed an increase in solubility proportional to the concentration of the alkaline solution. The solubility decreased in the order metakaolinite > metamontmorillonite > metaillite. Thereby, dissolution was incomplete for all three clay minerals (<90%) after 7 days and congruent for metakaolinite and metaillite but incongruent for metamontmorillonite.

The properties that might influence the sequestration of aflatoxin B1 (AfB1) were examined. Laser-diffraction, particle-size analysis (LDPSA) indicated that the particle size of the smectite influences the amount of AfB1 adsorbed. Effective adsorbent smectites disperse well under combined sodium hexametaphosphate solution and ultrasonic agitation. Particle size explained 66% of the variability for most of the samples investigated in an ‘as-received’ state. One effective adsorbent smectite was especially well aggregated and required additional physical dispersion, thus raising the correlation to 73%. Transmission electron microscope (TEM) images show typical smectites and reveal the very diverse morphology of smectites in bentonites. Thin, cloud-like smectite, in TEM images, related positively to AfB1-adsorption capacity. Particles that often fold and are usually ∼0.5 µm across seem to be optimal. The selection of criteria for evaluating these smectites provides a scientific basis for their selection to obtain reliable performance. Particle size is of particular importance as outlined below, and use of LDPSA makes it possible to perform the analysis efficiently and with precision.

Corrosion of steel canisters containing buried high-level radioactive waste is a relevant issue for the long-term integrity of repositories. The purpose of the present study was to evaluate this issue by examining two differently corroded blocks originating from a full-scale in situ test of the FEBEX bentonite site in Switzerland. The FEBEX experiment was designed initially as a feasibility test of an engineered clay barrier system and was recently dismantled after 18 years of activity. Samples were studied by ‘spatially resolved’ and ‘bulk’ experimental methods, including Scanning Electron Microscopy, Elemental Energy Dispersive Spectroscopy (SEM-EDX), μ-Raman spectroscopy, X-ray Fluorescence (XRF), X-ray Diffraction (XRD), and 57Fe Mössbauer spectrometry, with a focus on Fe-bearing phases. In one of the blocks, corrosion of the steel liner led to diffusion of Fe into the bentonite, resulting in the formation of large (width > 140 mm) red, orange, and blue colored halos. Goethite was identified as the main corrosion product in the red and orange zones while no excess Fe2+ (compared to the unaffected bentonite) was observed there. Excess Fe2+ was found to have diffused further into the clay (in the blue zones) but its speciation could not be unambiguously clarified. The results indicate the occurrence of newly formed octahedral Fe2+ either as Fe2+ sorbed on the clay or as structural Fe2+ inside the clay (following electron transfer from sorbed Fe2+). No other indications of clay transformation or newly formed clay phases were found. The overall pattern indicates that diffusion of Fe was initiated when oxidizing conditions were still prevailing inside the bentonite block, resulting in the accumulation of Fe3+ close to the interface (up to three times the original Fe content), and continued when reducing conditions were reached, allowing deeper diffusion of Fe2+ into the clay (inducing an increase of 10–12% of the Fe content).

The present study provides an example of the accurate identification of polytypes of trioctahedral 1:1 layered silicates from single-crystal X-ray diffraction data collected with the aid of a four-circle diffractometer equipped with an area detector. Single crystals of the mineral cronstedtite from the Nagybörzsöny gold ore deposit, northern Hungary, were studied. The chemical composition of some crystals was determined by electron probe microanalysis (EPMA). The precession-like images of the reciprocal space (RS) sections created by the diffractometer software and presented in the study were used to determine the OD (ordered-disordered) subfamilies (Bailey’s groups A, B, C, D) and particular polytypes. With one exception, all crystals studied belong to subfamily A. The rare polytype 1M, a = 5.51, b = 9.54, c = 7.33 Å, β = 104.5°, space group Cm is relatively abundant in this occurrence. Another polytype 3T, a = 5.51, c = 21.32 Å, space group P31 was also found. Both polytypes occur separately or in mixed, mostly 1M dominant crystals. Some 1M polytype crystals are twinned by order 3 reticular merohedry with a 120° rotation along the chex axis as the twin operation. A rare 1M+3T mixed crystal with 1M part twinned also contains a small amount of subfamily C. A possible presence of the most common 1T polytype of this subfamily cannot be confirmed because of overlap of the characteristic reflections with those of 3T. Several completely disordered crystals produced diffuse streaks instead of discrete characteristic reflections on the RS sections. The EPMA revealed Fe, Si, traces of Mg, Al, S, and Cl. One black crystal originally considered to be cronstedtite was identified as (111) twinned sphalerite. Some crystals of cronstedtite are covered partially by a honey-brown crust or small crystals of siderite.

The double hydroxide of Li+ and Al3+ is an anionic clay comprising positively charged metal hydroxide layers and intercalated anions. While the structure of the iono-covalently bonded metal hydroxide layer is well known, relatively less knowledge is available regarding the manner in which the anions and water molecules are packed in the interlayer region. The sulfate ion is of special interest as it can potentially intercalate in a multiplicity of orientations and grow an extended hydration sphere. The sulfate-intercalated double hydroxide was synthesized by the imbibition of Li2SO4 into both the gibbsite and bayerite forms of Al(OH)3 to obtain layered double hydroxides with the nominal formula Li2Al4(OH)12SO4·nH2O (n = 4–8). The as-prepared compounds were poorly ordered and did not yield any structural information. Temperature-induced partial dehydration yielded ordered phases of different structures in the two systems. Simulation of the powder patterns of different model structures, followed by structure refinement in both direct and reciprocal spaces, showed that the gibbsite-derived phase yielded a two-layer polytype of hexagonal symmetry (space group P63/m). The local symmetry of the sulfate ion was close to D2d with one of the C2 axes of the SO42− being nearly parallel to the c axis of the crystal. The bayerite-derived phase yielded a one-layer polytype of monoclinic symmetry (space group C2/m). The sulfate ion was oriented with its C3 axes tilted away from the stacking direction. Cooling and rehydration (relative humidity ~70%) resulted in a reversible expansion of the basal spacing due to the ingress of water molecules from the ambient humidity into the interlayer region. Hydration in both cases resulted in turbostratic disorder. The disorder in the bayerite-derived phase was a result of random intergrowth of motifs with rhombohedral and monoclinic symmetries.

Sepiolite and palygorskite are common as layers and nodules in the Neogene lacustrine sediments of the Eskişehir area. This study aims to determine their mineralogical and geochemical characteristics, plus the distribution of these economically important sepiolite and palygorskite deposits within the lacustrine environment. Using these data the research goes on to discuss the environmental conditions for their formation. Sepiolite and palygorskite layers are associated with dolomite, marlstone, and argillaceous limestone. The sepiolite nodules (meerschaum), which are former magnesite gravels, are observed in the Upper Miocene reddish-brown fluvial deposits derived from the ophiolite and its fractureinfills at the northern margin of the basin. Sepiolite and palygorskite are only sparsely associated with dolomite and accessory magnesite, quartz, feldspar, and amphibole. Sepiolite and palygorskite fibers formed as oriented platy fan, interwoven, and knitted aggregates in the absence of dolomite indicated precipitation from supersaturated solution. Sepiolite and palygorskite fibers edging dolomite crystals postdate dolomite and formed through precipitation in a vadose environment under semi-arid to arid climatic conditions. High values of Mg+Fe+Ni and enrichment of light rare earth elements (LREE) relative to middle rare earth elements (MREE) and heavy rare earth elements (HREE), Sr content, depletion of Rb+Ba and K, and negligible negative Eu anomalies all reflect the derivation from the Paleozoic metamorphic and Upper Cretaceous ophiolitic rocks. Locally, Upper Miocene to Lower Pliocene volcanic, volcanoclastic, and fluvio-lacustrine sedimentary rocks supplied the required Si, Mg, Al, and Fe for precipitation of Al-sepiolite and Mg-palygorskite with average structural formulae of Si11.91Al0.09O30Mg6.60Al0.78Fe0.13 (OH)4Na0.12K0.06(OH2)4·nH2O and Si7.74Al0.26O20Mg2.52Al1.13Fe0.38(OH)2(OH2)4Na0.32K0.14 Ca0.12·nH2O, respectively. In contrast to the layered sepiolites, the absence of Al and high Ni content in sepiolite nodules suggest formation through replacement of magnesite gravels at shallow burial in an alkal ine environment. The calculated meerschaum sepiol ite chemical formula i s: Si12.02O30Mg7.87Fe0.01(OH)4Na0.13K0.03(OH2)4·nH2O.

Kaolins and clays are important raw materials for production of supplementary cementitious materials and geopolymer precursors through thermal activation by calcination beyond dehydroxylation (DHX). Both types of clay contain different polytypes and disordered structures of kaolinite but little is known about the impact of the layer stacking of dioctahedral 1:1 layer silicates on optimum thermal activation conditions and following reactivity with alkaline solutions. The objective of the present study was to improve understanding of the impact of layer stacking in dioctahedral 1:1 layer silicates on the thermal activation by investigating the atomic structure after dehydroxylation. Heating experiments by simultaneous thermal analysis (STA) followed by characterization of the dehydroxylated materials by nuclear magnetic resonance spectroscopy (NMR) and scanning electron microscopy (SEM) together with first-principles calculations were performed. Density functional theory (DFT) was utilized for correlation of geometry-optimized structures to thermodynamic stability. The resulting volumes of unit cells were compared with data from dilatometry studies. The local structure changes were correlated with experimental results of increasing DHX temperature in the following order: disordered kaolinite, kaolinite, and dickite, whereupon dickite showed two dehydroxylation steps. Intermediate structures were found that were thermodynamically stable and partially dehydroxylated to a degree of DHX of 75% for kaolinite, 25% for disordered kaolinite, and 50% for dickite. These thermodynamically stable, partially dehydroxylated intermediates contained AlV while metakaolinite and metadickite contained only AlIV with a strongly distorted coordination shell. These results indicate strongly the necessity for characterization of the structure of dioctahedral 1:1 layer silicates in kaolins and clays as a key parameter to predict optimized calcination conditions and resulting reactivity.

Understanding the mechanisms for illitization of clay minerals has important applications in reconstructing geologic histories and determining the origins of physical and chemical characteristics of buried sediments. While many studies have been carried out on this topic, few have focused on the mechanism of illite formation from kaolinite. The purpose of this study was to investigate more deeply the illitization of kaolinite in KOH solution at a high solid/liquid ratio (1000 mg/mL). X-ray diffraction (XRD) and infrared spectroscopy were used to follow the formation of new crystalline phases and the composition of the octahedral sheet, while the transformation of the Si and Al local environments was analyzed by 29Si and 27Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). The results revealed that the first reaction stage consists of the diffusion of Al from the octahedral to the tetrahedral sheet of the kaolinite TO layers, giving rise to the precursors of the illite/muscovite nuclei. Combination of XRD with 27Al MAS NMR measurements indicated that a minimum amount of tetrahedral Al is required in the original TO layer before condensation of a second tetrahedral sheet occurs to complete the formation of the illite/muscovite TOT layers.

Swell-shrink clays are widely distributed in the Guangxi province of southern China in the form of expansive soils and lateritic clays. They have high particle dispersion, poor permeability, and significant swell-shrink properties. In recent decades, a series of problems closely related to the physical-mechanical properties of the swell-shrink clays have been encountered in various engineering projects. Mineral composition is a critical factor affecting the physical-mechanical properties of these clays. However, determining accurately their mineral compositions is difficult because the analytical methods available are expensive, time consuming, and have a high possibility of errors. Therefore, identifying a method suitable for quantitatively analyzing the mineral composition of the swell-shrink clays is necessary. In the current study several swell-shrink clays, including two expansive soils and four lateritic clays, from the Guangxi region were investigated. Qualitative analytical methods such as differential thermal analysis (DTA) and X-ray diffraction (XRD) were conducted to identify the mineral composition of the soils. The results indicated that the expansive soils were composed mainly of quartz (Qz), montmorillonite (Mnt), illite (Ilt), and kaolinite (Kln). The Baise specimen also contained a certain amount of calcite (Cal), while the lateritic clays primarily contained Kln and goethite (Gth) as well as lesser amounts of Qz and gibbsite (Gbs). On the basis of the aforementioned results, rough quantitative analyses of the mineral compositions were conducted using X-ray fluorescence (XRF) and the Bogue method. The results indicated that the lateritic clay samples from Wuming, Guilin, and Liuzhou contained 70–80% Kln, while the Laibin lateritic clay was 50% Kln. The lateritic clays contained ~10% Gth. The expansive soils were 30–40%, 25–30%, and 10–15% of Ilt, Qz, and Mnt, respectively. Finally, the relationships between the mineral compositions, zeta potentials, and free swelling ratios are discussed briefly. This investigation indicated that the zeta potential was mainly related to the type and content of clay minerals in the soil when neutral water was used as the free solution (pH = 7). The correlation between the swelling index and the zeta potential of the expansive soils was greater than that of the lateritic clays, which indicated that the swelling properties of expansive soils were more affected by the clay mineral composition than those of the lateritic clays. The results provide a systematic method for the qualitative and quantitative analysis of the mineral composition of swell-shrink clays and primary data for studying how mineral composition affects the physical properties of swell-shrink clays in the study area.

A calorimetric method for determining isothermal partial and integral heats of hydration reactions ($\text{Δ}{\overline{H}}_{\text{R,}T,P}$${\rm{\Delta }}{\bar H_{{\rm{R,}}T,\,P}}$ and $\text{Δ}{\stackrel{\sim }{H}}_{\text{R,}T,P}$${\rm{\Delta }}{\tilde H_{{\rm{R,}}T,\,P}}$, respectively) in zeolites and other mineral hydrates is presented. The method involves immersing a dehydrated sample in a humid gas stream under isothermal conditions within a thermal analysis device that records simultaneous differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA) signals. Monitoring changes in sample mass (corresponding to extent of reaction progress) coincident with a quantitative measurement of heat flow allows for direct detection of $\text{Δ}{\overline{H}}_{\text{R,}T,P}$${\rm{\Delta }}{\bar H_{{\rm{R,}}T,\,P}}$ as a function of the extent of hydration, which can be integrated to determine $\text{Δ}{\stackrel{\sim }{H}}_{\text{R,}T,P}$${\rm{\Delta }}{\tilde H_{{\rm{R,}}T,\,P}}$. In addition, it eliminates uncertainties associated with imprecise knowledge of the starting and final states of a sample during hydration. Measurement under isothermal conditions removes uncertainties associated with heat capacity effects that complicate interpretations of DSC measurements of dehydration heats conducted under traditional scanning temperature conditions. Example experiments on the zeolites natrolite, analcime and chabazite are used to illustrate strategies for quantifying $\text{Δ}{\overline{H}}_{\text{R,}T,P}$${\rm{\Delta }}{\bar H_{{\rm{R,}}T,\,P}}$ and $\text{Δ}{\stackrel{\sim }{H}}_{\text{R,}T,P}$${\rm{\Delta }}{\tilde H_{{\rm{R,}}T,\,P}}$ and minimizing errors associated with baseline uncertainties. Results from this method agree well with previously published values determined by other calorimetric techniques and regression of phase equilibrium data. In the case of chabazite, the results allowed detailed measurements of the variation in $\text{Δ}{\overline{H}}_{\text{R,}T,P}$${\rm{\Delta }}{\bar H_{{\rm{R,}}T,\,P}}$ for energetically different water types encountered progressively as the sample absorbed water. This technique complements and in many cases improves the quality of thermodynamic data obtained through phase equilibrium observations and other calorimetric techniques.