The crystal structure of cronstedfite-1T was refined in space group P31m, using two crystals: a triangular tabular crystal from Herja, Romania and a conical crystal from Lostwithiel, Cornwall, England. The Herja sample has the composition of (Fe2+2.20Fe3+0.80)(Si1.20Fe3+0.78Al0.02)O5(OH)4 and the Lostwithiel sample has the composition of (Fe2+2.32Fe3+0.68)(Si1.32Fe3+0.66Al0.02)O5(OH)4. The results of refinements are as follows: a = 5.512(1) Å, c = 7.106(1) A, R = 3.07%, and 342 independent reflections; and a = 5.503(1), c = 7.104(1) Å, R = 2.24%, and 335 independent reflections for the Herja and Lostwithiel samples, respectively. The structure consists of one tetrahedral and one octahedral sheet. There is one octahedral site, M1, occupied by Fe only, and one tetrahedral site, T1, occupied by Si and Fe in the ratio of 0.617(8):0.383 (Herja) and 0.699(6):0.301 (Lostwithiel). Positions of two hydrogen atoms were determined from a difference map for the Lostwithiel data. The ditrigonalization angle of the tetrahedral sheet is α = −11.5° (Herja) and α = −11.1° (Lostwithiel), and the structures have a Franzini-layer type of B. The crystals studied are affected by ± b/3 stacking faults which produced slight streaking of h - k ≠ 3n reflections.

Silanol groups in protonated magadiite (H-magadiite) were characterized by 1H and 2H solid-state nuclear magnetic resonance (NMR). H-magadiite and deuterated (D) magadiite were synthesized by the treatment of Na-rich magadiite with 0.2 N HC1 and 0.2 N DC1, respectively. In the 1H NMR spectrum measured at room temperature, silanol groups of H-magadiite showed two signals at 3.75 and 5.70 ppm, indicating that two types of silanol groups were present. The ratio of silanol groups associated with strong hydrogen bonding (5.70 ppm) to those with weaker hydrogen bonding (3.75 ppm) was 2 to 1. The 2H NMR spectra of deuterated magadiite were measured in the temperature range from 150 to 440 K. In the spectra measured at temperatures below 294 K, silanol groups showed Pake doublet patterns. These patterns were composed of two components corresponding to the two types of silanol groups shown in the 1H NMR analysis. Both silanol groups produced wobbling motions with increasing temperature. Above 294 K, the profile of the Pake doublet pattern was transformed gradually to a near triangular pattern, indicating that the silanol groups underwent other motions also, such as a two-site jump.

The incorporation of transition metals into hematite may limit the aqueous concentration and bioavailabity of several important nutrients and toxic heavy metals. Before predicting how hematite controls metal-cation solubility, we must understand the mechanisms by which metal cations are incorporated into hematite. Thus, we have studied the mechanism for Ni2+ and Mn3+ uptake into hematite using extended X-ray absorption fine structures (EXAFS) spectroscopy. EXAFS measurements show that the coordination environment of Ni2+ in hematite corresponds to that resulting from Ni2+ replacing Fe3+. No evidence for NiO or Ni(OH)2 was found. The infrared spectrum of Ni-substituted hematite shows an OH-stretch band at 3168 cm−1 and Fe-OH bending modes at 892 and 796 cm−1. These vibrational bands are similar to those found in goethite. The results suggest that the substitution of Ni2+ for Fe3+ is coupled with the protonation of one of the hematite oxygen atoms to maintain charge balance.

The solubility of Mn3+ in hematite is much less extensive than that of Ni2+ because of the strong Jahn-Teller distortion of Mn3+ in six-fold coordination. Structural evidence of Mn3+ substituting for Fe3+ in hematite was found for a composition of 3.3 mole % Mn2O3. However a sample with nominally 6.6 mole % Mn2O3 was found to consist of two phases: hematite and ramsdellite (MnO2). The results indicate that for cations, such as Mn3+ showing a strong Jahn-Teller effect, there is limited substitution in hematite.

Illitization of smectite during progressive burial diagenesis occurs differently in sandstone and mudstone, which are interbedded in the sedimentary sequence of the Niigata basin. Reaction progress of illitization of smectite via mixed-layer illite-smectite (I-S) in the mudstone is more complete than in the sandstone. In sandstone, smectite converts to (Reichweit, R ≥ 3) I-S and illite via random (R = 0) I-S to ordered (R = 1) I-S, and authigenic chlorite and quartz form as products of the illitization of smectite.

The original composition of detrital smectite and the occurrence of Na+, K+, Ca2+, Mg2+, and Fe2+ in pore fluids partly control both illitization of smectite and the resulting authigenic mineral products in the diagenetic process. In mudstone, detrital smectite is K- and Si-rich in composition, and the illitization of smectite indicates that the original composition is mostly inherited. Excess silica owing to illitization is released to produce authigenic quartz. In sandstone, smectite forms primarily by precipitation. The evolving compositions produced by early illitization form smectite, then random (R = 0) I-S, and then ordered (R = 1) I-S. These transitions are related to compositions of pore fluid. Changes in K/(K + Ca + Na) vs. K + Ca + Na imply that the increase of interlayer cations occurs by absorption and smectite transforms to random (R = 0) I-S, followed by the exchange of interlayer cations to ordered (R = 1) I-S with increasing diagenetic grade. Late illitization from (R = 1) I-S to R ≥ 3 suggests decomposition of smectite and early I-S with an increase in the number of illite layers. Dissolution experiments of host rocks with pure water and 0.01 M HCl solution reflect the differences in chemistry of the original pore fluid and authigenic carbonate in the process of diagenesis of clastic rocks. These results explain how chemical composition produces large variations in transformation temperature of smectite to illite in the diagenetic process.

Sorptive properties of organoclays may be greatly influenced by the physicochemical properties of organic sorbates. Hexadecyltrimethylammonium(HDTMA) clays were prepared using a high-charge smectite (HDTMA-SAz-1), a low-charge smectite (HDTMA-SWy-2), and an illite (HDTMA-ILL). The resultant organoclays were used to sorb aqueous phase 1,2-dichlorobenzene (o-DCB), 1,3-dichlorobenzene (m-DCB), and 1,4-dichlorobenzene (p-DCB). Sorptive characteristics of these compounds were determined by their molecular polarities (o-DCB > m-DCB > p-DCB) and the HDTMA-clay interlayer distance. HDTMA-ILL was used for comparison to HDTMA-SAz-1 and HDTMA-SWy-2. All dichlorobenzene isomers were directly intercalated in the interlayers of HDTMA-SAz-1, causing interlayer expansion. o-DCB and m-DCB were not intercalated in the interlayers of HDTMA-SWy-2 at low concentrations, but intercalation occurred at higher concentrations, which caused interlayer expansion. The concentration needed to produce interlayer expansion depended on the solute molecular polarity, hence a higher concentration of m-DCB than o-DCB was required. p-DCB was sorbed primarily by the HDTMA phase on the external surfaces of HDTMA-SWy-2. In the presence of chlorobenzene (CB), p-DCB sorption by HDTMA-SWy-2 is greatly enhanced, owing to the interlayer expansion by CB and a cosolvent effect. Sorption of o-DCB resulted from both direct solvation-type interactions with HDTMA and partitioning into HDTMA. Such sorption results in double-sigmoid isotherms. m-DCB weakly solvates the HDTMA and partitions into the HDTMA, displaying either a double-sigmoid or a type-III isotherm depending on clay type. p-DCB lacks ability to solvate HDTMA and partitions into HDTMA as its sole mechanism, producing type-III isotherms. HDTMA-clays are potentially effective for treating dichlorobenzene-contaminated wastewater.

Two analogous inorganic-organic hybrids with a phyllosilicate-like structure SILMg1 and SILMg2, containing 3-aminopropyl- and N-propylethylenediaminetrimethoxysilane were synthesized through a sol-gel process. These hybrids adsorbed divalent cations of cobalt, nickel, copper, and zinc from aqueous solution to give the effectiveness of adsorption capacities in the sequence Cu2+ > Zn2+ > Ni2+ > Co2+. SILMg1 has a higher capacity of adsorption than SILMg2. Elemental analysis, X-ray diffractometry, thermal analysis, infrared and nuclear magnetic resonance spectroscopies, and energy dispersive system microscopy characterized all hybrids. The proposed adsorption mechanism involves dissolution of the precursor matrix, formation of a phyllosilicate around the adsorbed ion, and a complexation of the cation by the amino-pendant groups in the interlayer. These new phyllosilicates are more crystalline than the original hybrids. The adsorption of Co2+ increases the interlayer distance to maximum values of 1.81 and 2.24 Å for SILMg1 and SILMg2, respectively. Thermal analysis data showed a decrease of thermal stability with cation adsorption. Si-O-Si groups were detected by infrared spectroscopy in all hybrids and a band at 1384 cm-1 was assigned to the nitrate counter anion, which indicates the participation of this ion in the sphere of coordination of the interlayer complexes. The photomicrographs obtained by scanning electron microscopy showed the organized distribution of the sheet structure for these synthesized phyllosilicates.

Experimental alteration of volcanic tuff from Almeria, southeastern Spain, was performed in solutions with different Na/K ratios (0.01, 1, 10, and 100), different total salt concentrations (0.01, 0.1, 0.2, 0.33, and 1 M), and in deionized water, at 60, 80, 120, and 160°C, for periods of 60, 90, 180, and 360 d. Two particle size fractions of volcanic tuff were used: 10–200 and 20–60 μm. Alteration products were examined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), laser-particle size analysis, scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (SEM-EDS), image computer analysis, and transmission electron microscopy with microanalysis (TEM-AEM). XRD detected neoformed phases only in the products from experiments of 180–360 d at high temperatures (120–160°C), and with Na/K ratios above unity and in deionized water. The synthesized phase is a random mixed-layer illite-smectite (I-S) with 75% smectite. The quantity of newly formed I-S, determined by FTIR, ranged between 3–30%. There was no apparent change in grain size and shape of the grains after the experiments as compared to before.

SEM-EDS and TEM-AEM revealed the following alteration sequence: 1) intense etching on glass-grain surfaces; 2) formation of hemispherical morphologies on grain surfaces; 3) precipitation of very thin, individual flakes of illite-smectite on glass-grain surfaces; 4) development of I-S at the edges of glass grains; and 5) development of I-S honeycomb structures either covering large areas of the glass grains or resulting from the complete alteration of glass grains. A direct transformation of glass to I-S seems to be the major reaction mechanism, although there also is evidence of glass dissolution and subsequent I-S precipitation.

Two series of pillared clays were prepared from a purified montmorillonite (95%) from La Serrata of Nijar, Spain, and polycations of Al and Zr using various methods. The effect of both the pillaring cation and the procedure of preparation on the physicochemical characteristics of the resulting materials was studied. Changes in texture were determined by X-ray diffraction (XRD) and N2 adsorption at 76 K and changes in acidity were determined by thermogravimetry following pyridine adsorption at room temperature and further desorption at a constant heating rate of 10 K min−1 in the range of 298–623 K. The relation between the size and charge (n/q) of the pillaring cation, which is dependent on the degree of cation hydrolysis, is the main factor affecting pore size and acidity of the synthesized materials. The pH of the pillaring solution affects the stability of the parent clay and the properties of the pillared clay. Below a pH of 3 and depending on contact time, the montmorillonite may delaminate and partially dissolve to produce products that affect the properties of the resulting materials. Microporosity increases for both Al or Zr-pillared clays. For Zr-pillared clays, microporosity is accompanied by changes in the mesoporosity and macroporosity as a result of clay delamination. Acidity dramatically increases by pillaring, especially strong acidity, and the acid strength distribution depends on starting salt concentration, aging time, and temperature.

Area-weighted thickness distributions of fundamental illite particles for samples of illite and illite-smectite from seven locations (including bentonites and hydrothermally altered pyroclastics) were measured by Pt-shadowing technique, by transmission electron microscopy. Most thickness distributions are described by lognormal distributions, which suggest a unique crystallization process. The shapes of lognormal distributions of fundamental illite particles can be calculated from the distribution mean because the shape parameters α and β2 are interrelated: β2= 0.107α − 0.03. This growth process was simulated by the mathematical Law of Proportionate Effect that generates lognormal distributions. Simulations indicated that illite particles grow from 2-nm thick illite nuclei by surface-controlled growth, i.e., the rate of growth is restricted by how rapid crystallization proceeds given a near infinite supply of reactants, and not by the rate of supply of reactants to the crystal surface. Initially formed, 2-nm thick crystals may nucleate and grow within smectite interlayers from material produced by dissolution of single smectite 2:1 layers, thereby transforming the clay from randomly interstratified (Reichweite, R = 0) to ordered (R = 1) illite-smectite after the smectite single layers dissolve. In this initial period of illite nucleation and growth, during which expandable layers range from 100 to 20%, illite crystals grow parallel to [001]* direction, and the dimensions of the (001) plane are confined to the size of the original smectite 2:1 layers. After nucleation ceases, illite crystals may continue to grow by surface-controlled growth, and the expandable-layer content ranges from 20 to 0%. This latter period of illitization is characterized by three-dimensional growth. Other crystal-growth mechanisms, such as Ostwald ripening, supply-controlled growth, and the coalescence of smectite layers, do not produce the observed evolution of α and β2and the observed shapes of crystal thickness distributions.

The formation of kaolin-group minerals in the weathering profile of granite, under the humid, temperate climate as found in Korea, was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron microprobe analysis (EMA). The granite was gradually weathered to saprolite. K-rich feldspar was not weathered in the profile, but plagioclase partially weathered to halloysite septa (i.e., wall-like masses). At the bottom of the profile, biotite had weathered to regularly interstratified biotite-vermiculite (B-V), and subsequently to kaolinite, with a considerable increase in grain volume. In the upper part of the profile, loose aggregates of transported clays, including halloysite and kaolinite, coated the preformed halloysite septa in the weathered plagioclase. Halloysite had precipitated as a metastable phase in the microfissures of partially weathered plagioclase. Kaolinite had precipitated heavily in the weathered biotite, where surfaces supply abundant templates facilitating the nucleation of kaolinite. The localized crystallization of halloysite and kaolinite, depending on the distribution of primary minerals, strongly influenced the kaolin mineralogy of the granite weathering profile.

Mineralogical studies were performed on authigenic clay minerals of mudrocks, sandstones, and bentonites from 38 boreholes in the Late Permian coal measures of the Bowen Basin. Clay-mineral separations of samples from the northern Bowen Basin consist mainly of (Reichweite, R) R = 1 and R ≥ 3 interstratified illite-smectite (I-S), chlorite, and kaolinite. In the southern Bowen Basin, samples from higher stratigraphie sections are characterized by randomly ordered (R = 0) I-S mixed layers, and kaolinite and chlorite in smaller amounts. Samples from the lower sections consist of (R ≥ 3) I-S, chlorite, chlorite-rich chlorite-smectite (C-S), and laumontite.

Examination of the mineralogy and distribution of authigenic clay minerals from the Late Permian coal measures in the northern part of the Bowen Basin indicated that the presence of clay minerals is not systematically related to depth and clay occurrences do not occur regularly. These mineralogical variations of clay in volcaniclastic sediments are incompatible with thermal control. Variations in the rate of fluid flow and potassium supply owing to permeability exert major influences on clay-mineral paragenesis and the reaction of illitization. In more permeable zones (possibly faults or fracture zones), highly illitic clays with lath-shaped morphologies may have precipitated directly from potassium-rich fluids migrating from deeper parts of the basin. In addition, abundant chlorite precipitated contemporaneously with illitic clays, which may have resulted from sufficient magnesium and iron occurring in the fluids as a result of dissolution of intermediate or mafic-rock fragments. At the same time, clay paragenesis with less illitic I-S, kaolinite, and minor chlorite occurs outside the channelized zones of high fluid flow, where a diffusive-flow regime may have predominated with lower ratios of the activities of K+ and H+ (i.e., αK+/αH+) in the solutions.

In the southern Bowen Basin, depth-related changes in the distribution of clay minerals are evident and may be indicative of thermal control on clay-mineral reactions. Zeolites are present locally in the Late Permian volcaniclastic rocks in the southern Bowen Basin, but not in the north. This is attributed to a low ratio of αCO2/αH2O (where α = activity) and/or more saline and alkaline solutions.

A new method for the prediction of Gibbs free energies of formation for hydrated clay minerals is proposed based on the parameter ΔGO= Mz+(clay) characterizing the oxygen affinity of the cation Mz+. The Gibbs free energy of formation from constituent oxides is considered as the sum of the products of the molar fraction of an oxygen atom bound to any two cations multiplied by the electronegativity difference defined by the ΔGO= Mz+(clay) between any two consecutive cations. The ΔGO= Mz+(clay) value, using a weighting scheme involving the electronegativity of a cation in a specific site (interlayer, octahedral, or tetrahedral) is assumed to be constant and can be calculated by minimization of the difference between experimental Gibbs free energies (determined from solubility measurements) and calculated Gibbs free energies of formation from constituent oxides. Results indicate that this prediction method compared to other determinations, gives values within 0.5% of the experimentally estimated values. The relationships between ΔGO= Mz+(clay) corresponding to the electronegativity of a cation in either interlayer or octahedral sites and known ΔGO= Mz+(aq) were determined, thereby allowing the prediction of the electronegativity of transition metal ions and trivalent ions in hydrated interlayer sites and octahedral sites. Prediction of Gibbs free energies of formation of any clay mineral with various ions located in the interlayer and with different cations in octahedral sites is possible. Examples are given for Al-rich montmorillonite from Aberdeen, transition element-exchanged montmorillonite, and Ni-rich stevensite, and the results appear excellent when compared to experimental values.

Mining operations during the early 1990s at Uley Graphite Mine near Port Lincoln on southern Eyre Peninsula, South Australia, uncovered abundant nontronite veins in deeply weathered granulite facies schist, gneiss, and amphibolite of Palaeoproterozoic age. Two types of nontronite are present: a bright yellowish-green clay (NAu-1) distributed as veinlets and diffuse alteration zones within kaolinized schist and gneiss, and a massive to earthy, dark-brown clay (NAu-2) infilling fracture networks mainly in amphibolite or basic granulite. The nontronites are the product of low-temperature hydrothermal alteration of primary minerals, biotite, and amphibole. The principal chemical difference between NAu-1 and NAu-2 is a higher alumina content in NAu-1, which was either inherited during hydrothermal alteration of biotite in the host rock or acquired through recrystallization of nontronite during subsequent weathering and associated kaolinization. Sufficient bulk samples of both NAu-1 and NAu-2 were collected to supplement reference nontronite of the Source Clay Repository of The Clay Minerals Society. The clay fraction of the bulk samples is typically >85%. NAu-1 contains minor kaolin and quartz which are easily removed to give a high purity nontronite of composition M+1.05[Si6.98Al1.02][Al0.29Fe3.68Mg0.04]O20(OH)4, similar to that of nontronite from Garfield, Washington. NAu-2 contains fewer total impurities but the presence of trace amounts of submicron carbonate and iron oxyhydroxide requires additional chemical treatment to produce a nontronite of purity comparable to NAu-1. Composition of NAu-2 was calculated as M+0.72[Si7.55Al0.45][Fe3.83Mg0.05]O20(OH)4, although infrared data indicate that at least some Fe is in tetrahedral coordination.

The Dongrae fault within the Yangsan fault system is considered one of the major faults in the southeastern part of Korea, extending over 150 km. The results of K-Ar radiogenic dating of fault gouges collected from six localities show a relatively wide range in age from 57.5 million years ago (Ma) to 40.3 Ma. Fault gouges are composed of newly formed minerals, including smectite, illite, zeolite, kaolinite, K-rich feldspar, apatite, and pyrite. The occurrence of abundant smectite and illite-lMd with lesser quantities of zeolite suggests that the fault gouges experienced hydrothermal alteration at low temperatures. Smectite is probably unstable relative to other clay minerals, such as illite and zeolite. Considering that filiform mordenite is replacing the smectite, we suggest that mordenite formed by recrystallization involving a solid-state transformation. Under high fluid/rock ratios, smectite seems to have formed in the early stage of alteration. In contrast, zeolite minerals and authigenic K-rich feldspar progressively appeared with time as the fluid/rock ratio decreased with the changing chemistry of the hydrothermal fluids. The composition of clay minerals in the gouge materials probably was controlled by the chemistry and the amount of circulating fluids derived from adjacent granitic rocks.

Chromium(VI) in the environment is of particular concern because it is toxic to both plants and animals, even at low concentrations. As a redox-sensitive element, the fate and toxicity of chromium is controlled by soil reduction-oxidation (redox) reactions. In-situ remediation of chromium combines reduction of Cr(VI) to Cr(III) and immobilization of chromium on mineral surfaces. In this study, Fe-rich smectite, montmorillonite, illite, vermiculite, and kaolinite were examined to determine reactivity in sorption-reduction of Cr(VI). The clays were compared to forms that were reduced by sodium dithionite. Clays containing Fe(II) efficiently removed soluble Cr(VI) from solution. Chromium K-edge X-ray absorption near edge structure (XANES) suggested that clays containing Fe(II) reduced Cr(VI) to Cr(III), immobilizing Cr at the clay/water interface. Adsorption of Cr(VI) by the Fe(II)-containing clay was a prerequisite for the coupled sorption-reduction reaction. Sodium dithionite added directly to aqueous suspensions of non-reduced clays reduced Cr(VI) to Cr(III), but did not immobilize Cr on clay surfaces. The capacity of clays to reduce Cr(VI) is correlated with the ferrous iron content of the clays. For dithionite-reduced smectite, the exchangeable cation influenced the sorption reaction, and thus it also influenced the coupled sorption-reduction reaction of Cr(VI). The pH of the aqueous system affected both the amount of Cr(VI) reduced to Cr(III) and the partition of Cr(III) between aqueous and adsorbed species. A plot of pH vs. amount (adsorption envelope) adsorbed for the coupled sorption-reduction reaction of Cr by reduced smectite exhibited a similar pattern to that of typical anion-sorption.

The distribution and chemical state of Si in a synthetic 2-line ferrihydrite with a Si/(Si + Fe) molar ratio of 0.11 was studied. Heat treatment under oxidizing conditions shows that Si-rich ferrihydrite is stable to 400°C. The transformation to hematite and the formation of a polymerized amorphous-silica phase occur at 850°C. At this temperature, the specific surface area decreases greatly and the average pore diameter increases, which is indicative of sintering. Heating under severe reducing conditions causes a segregation of Si from Fe and results in a mixture of elemental Fe and SiO2. Surface and structural data suggest that Si is located near the particle surface where it limits the rearrangement of Fe octahedra to form hematite.

This study examines the evolution of the texture, structure, and chemical composition of rocks derived from clastic materials of the Ossa-Morena Zone (Hesperian Massif, Spain). Previous studies of phyllosilicates in these rocks (by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray analysis, and electron microprobe) indicated a temperature decrease from bottom (epizone conditions) to top (diagenetic conditions) of the rock section.

At the nanometer scale, phyllosilicate packets form large angles where grains intersect with no preferred orientation. With metamorphic grade, packets are wide and defect free, compared to packets at lower grade. These packets are ∼ 15 layers under diagenetic conditions to >80 layers in the epizone. Dioctahedral K-rich micas (muscovite, phengite, and illite) have coexisting 1Md, 1M, and 2M polytypes. Long-period polytypes of 4, 5, and 6 layers are reported for the first time in dioctahedral K-rich micas. The chemical compositions of the micas are nearly identical in the anchizone and the diagenetic zone, comprising an illitic (0.8 atoms per formula unit, a.f.u., of K) and a phengitic component (0.15 a.f.u, of Mg and 0.13 a.f.u, of Fe). Fe may correspond to a ferrimuscovitic substitution. Epizone samples have a high phengitic content (Mg = 0.24 a.f.u.) and almost no illite component. One diagenetic sample has coexisting berthierine, trioctahedral chlorite, sudoite, and corrensite. Berthierine and chlorite are identical in composition. Because of the clastic nature of the system, the composition of corrensite is not typical of other corrensites, with higher Al content, Fe/Mg ratio at ∼1, and K as the exchangeable cation.

Textural differences between the diagenetic zone and the anchizone are the progressive increase in the size of dioctahedral K-rich mica grains, which involves an increasing illite crystallinity based on the Kübler index. The chemical compositions of these micas are illite (diagenesis and anchizone) and phengite in the epizone. There are no intermediate phases, suggesting a compositional gap between illite and phengite. The coexistence of different polytypes of dioctahedral K-rich micas and the absence of chemical homogeneity indicate disequilibrium in the Cambrian pelitic rocks studied.

Chlorite and illite are commonly associated with ubiquitous secondary K-rich feldspar in the rocks located immediately above and below the Precambrian-Paleozoic unconformity in southwestern Ontario, and elsewhere in the mid-continent of North America. This alteration assemblage is attributed to long-distance migration of hot brines driven westward by orogenic processes originating along the eastern seaboard of North America. The δD and δ18O values of chlorite and illite, plus K-Ar dates for secondary K-rich feldspar and illite, were used to determine the nature, origin, and timing of the fluids that altered Precambrian granites and their overlying rocks in southwestern Ontario. The δ18O values of the chlorite-forming fluids are best explained by initial hot brines (≥50°C) evolved mostly from seawater. Secondary K-rich feldspar formation followed shortly thereafter, as the fluids cooled and perhaps mixed with meteoric water. Regional migration of the brines was induced by Taconic orogenic events to the east. The hydrogen and oxygen isotopic compositions for the secondary illite of the early to mid-Carboniferous indicate its crystallization from local meteoric water at low temperatures (40–55°C). Infiltration of local meteoric water into the Paleozoic and uppermost altered Precambrian rocks occurred during uplift, erosion, and subaerial exposure of local arches in southern Ontario. The local basement reactivation and associated secondary illite formation in this portion of the North American hinterland was likely a distal expression of east-coast Acadian and Alleghanian orogenic activity.

The bleaching of cottonseed oil by alumina-pillared (Al-pillared) acid-activated clays was investigated. Acid activation of a Ca-rich montmorillonite (CMS STx-1) following treatment with 1, 4, and 8 eq/L sulfuric-acid solutions, as well as subsequent pillaring with alumina, produces new materials. These materials have bleaching properties dependent upon the extent of activation of the clay prior to pillaring. The pillared acid-activated montmorillonites possessed higher bleaching efficiency compared to pillared products of the untreated clay. Mild activation of the montmorillonite matrix, pillaring with the Keggin ion [Al13O4(OH)24(H2O)12]7+, and calcination temperatures to 500°C produced materials with the best fractional degree of bleaching. Direct comparison to the performance of a commercial bleaching earth (Tonsil Optimum 214, Sud-Chemie AG. Moosburg, Germany) shows that the efficiency of the Al-pillared acid-activated montmorillonite may be improved. The optimization of the bleaching process is achieved via a judicious utilization of intermediate surface area, relatively high acidity, and enhanced pore volume.

X-ray phase analysis of clays is difficult because these materials generally consist of a mixture of different phases, i.e., mixed-layer minerals, individual clay minerals (non mixed-layer), and associated minerals, such as calcite and quartz. The analysis requires knowledge that presently is incorporated in a computer-based expert system. This expert system is capable of a) identification of associated minerals; b) identification of individual clay minerals; c) identification of the nature of the mixed-layer minerals; d) approximate structural characterization of the mixed-layer minerals; and e) precise structural determination of the mixed-layer minerals by comparison of experimental X-ray diffraction (XRD) patterns with calculated patterns for different models. Accuracy of the conclusions drawn by the expert system has been verified with literature data. Programs for the structural characterization of mixed-layer minerals must allow a) modification of the structural characteristics, abundances, and order-disorder distribution of the layers; b) modification of the distribution of the sizes of coherent scattering domains; and c) consideration of mixed-layer clays with more than two components. Two programs were written to calculate the XRD patterns of two- and three-component mixed-layer minerals consisting of any layer type and without any limitation in the order-disorder relationships.