Ordered illite/smectite (I/S) and illite in a pelitic rock from a prograde metamorphic sequence in North Wales were observed by transmission electron microscopy. The dominant phyllosilicate noted was diagenetic-metamorphic illite, occurring as subparallel packets of layers, each about a few hundred Ångstroms thick. It exhibited two-layer polytypism (presumably 2M1) and numerous strain features and had a composition of (K1.21Na0.12)(Al3.36Fe0.31Mg0.33)(Si6.28Al1.72)O20(OH)4.

I/S occurred as thick packets of wavy layers having 10-Å subperiodicity and sharp differences in contrast in successive lattice fringes. All stages in a replacement series were noted, from one or two layers of smectite within illite, through thin packets of I/S, to thick packets that contained inherited deformation textures of diagenetic-metamorphic illite. Deformed illite was replaced by I/S more commonly than was undeformed illite. The I/S replacing undeformed original illite had significantly greater order, primarily of R1 type (ISISIS…), than that replacing deformed illite. R> 1 I/S occurred as small crystallites and contained relatively less smectite than the ordered I/S, Single smectite layers were spaced within several illite layers, forming curved packets of layers. IISIIS… (R2) and IIISIIIS… (R3) ordering were present locally, as was discrete smectite. Analytical electron microscopic analyses indicated that the I/S, (K0.46Na0.43)(Al3.75Fe0.06Mg0.19)(Si6.26Al1.74)O20(OH)4, was rectorite-like in composition and had smaller (Mg + Fe) contents and greater Al/Si ratios than the coexisting illite, which was also anomalous in terms of general crystal-chemical relationships between coexisting illite and I/S in burial diagenesis environments. The I/S appears to have formed by replacement of diagenetic-metamorphic illite, presumably at very low temperatures under hydrous conditions via dissolution and crystallization.

The surface and charge characteristics of 6 allophanic clays originating from a climatosequence of Andisols have been studied by titration, ion retention, surface area, and reactivity measurements. Several properties of these clays, such as the pH of zero charge, the magnitude of the surface area, and the reactivity of structural hydroxyl groups, appear to be governed by their chemical composition, especially by their silica content. A similar relationship between the above properties and silica content also exists for synthetic aluminosilicate gels (often quoted in the literature as possible models of allophanes), despite their different structure to the natural clays. An explanation is that as desilication proceeds, octahedral polymeric units of aluminum progressively individualize in both the synthetic and natural samples. The surface areas of the aUophanic clays, based on the slope of the titration curve at pH 7, are closely related to the amounts of structural hydroxyl that can react with fluoride at about the same pH. The permanent negative charges are always very low, even for silica-rich, allophane-bearing samples. It is therefore suggested that all of these clays should be virtually free of tetrahedral aluminum.

The resolution of the infrared spectra of structural OH in kaolin-group minerals increases with decreasing temperature. Poorly crystalline kaolinite gives typical infrared spectra, which suggest the existence of kaolinite-, dickite-, and nacrite-like configurations. The relative amount dickite- and nacrite-like configurations compared with kaolinite-like configurations increases with decreasing crystallinity. Low-temperature infrared spectroscopy is a more sensitive means of estimating the degree of order of poorly crystalline kaolinite than is X-ray powder diffraction.

Three montmorillonites and a nontronite were reduced by sodium dithionite to obtain different amounts of Fe2+ in their octahedral sites. The mass ratio of water to clay, mw/mc was determined as a function of Fe2+ at several values of the swelling pressure, π. The value mwmc decreased markedly with increasing Fe2+ at each value of π for each clay. Moreover, curves of π vs. mwmc for the different clays were displaced downwards as Fe2+ increased. A straight line was obtained when In(π + 1) was plotted against 1/(mw/mc) however, at some oxidation states of three of the samples this line exhibited a sharp break at a specific value of 1/(w/mc. The slope of the line decreased for each clay as Fe2+ increased, and an increase in Fe2+ was accompanied by an increase in the cation exchange capacity. These observations are thought to be due to a collapse or partial collapse of the superimposed clay layers resulting from the increase in cation-exchange capacity.

Clay fractions separated from the A2, B, and C horizons of a soil formed on granite gneiss showed X-ray powder diffraction (XRD) spacings characteristic of trioctahedral illite. The trioctahedral illite was derived from biotite, and its development through various stages of weathering was followed by optical and electron microscopy combined with electron microanalysis. In the initial stages of weathering, Fe2+ within biotite was oxidized, without the loss of much K. During this process, biotite flakes became slightly buckled and fractured. Solutions moved into the damaged flakes leading to chemical weathering and exfoliation along cleavages and angular fractures. Major exfoliation broke up the flakes into segments, which themselves contained minor exfoliations and alterations along cleavage planes. The extent of exfoliation and alteration continued until thinner and shorter segments consisted almost wholly of thin (< 0.25 µm), parallel wafers separated by less compact layers of particles and microaggregates. The segments finally lost their shape and divided into clay-size particles. Parts of the thin wafers had the same chemical composition (and structure) as the original, intact flakes of oxidized biotite. The same parts of wafers retained some of the optical properties of the original biotite, and, when broken down to clay, they produced the XRD spacings of 10 and 1.54 Å, typical of fine-grained, trioctahedral mica (illite).

The dehydration temperature of K-montmorillonite, obtained by ion exchange of a Na-mont-morillonite, was determined at pressures to 2 kbar, using high-pressure differential thermal analysis. Dehydration reactions were found at about 50° and 100°C above the liquid-vapor curve of water. At pressures above the critical point of water the dehydration temperatures increased only slightly. The temperature of the first dehydration reaction is 10°C higher than for Na-montmorillonite, indicating a slightly greater stability of the hydration shell around the potassium interlayer cation. The second dehydration reaction occurs at a slightly lower temperature. The data were used to determine the enthalpy of the dehydration ΔH(dh) and the bonding enthalpy of the interlayer water ΔH(iw) at 1 atm. The first dehydration reaction of the K-exchanged montmorillonite has a ΔH(dh) = 46.16 ± 0.06 kJ/mole and a ΔH(iw) = 7.8 ± 0.5 kJ/mole, whereas for the second reaction, ΔH(dh) = 56.7 ± 2 kJ/mole and ΔH(iw) = 19.8 ± 2 kJ/mole. These values compare with a ΔH(dh) = 46.8 ± 0.3 kJ/mole and a ΔH(iw) = 7.8 ± 0.5 kJ/mole for the first dehydration reaction of the Na-montmorillonite and a ΔH(dh) = 62.9 ± 2 kJ/mole and ΔH(iw) = 27.1 ± 2 kJ/mole for the second dehydration.

The effect of Fe oxidation state on the surface charge (CEC) and solubility of smectites were studied using the <2-μm, Na+-saturated fraction of an Upton, Wyoming; a Czechoslovakian; and a New Zealand montmorillonite; and a Garfield, Washington, nontronite. The reduction of structural Fe3+ in the octahedral sheet of each clay produced a net increase in the negative surface charge of the clay. The observed cation-exchange capacities deviated from the linear relationship predicted by charge-deficit calculations, assuming changes only in the Fe2+/Fe3+ ratio, and reversibly followed Fe reduction according to a 2nd-degree polynomial function. The deviations suggest reversible changes in mineral structure and composition during Fe reduction.

These clays were susceptible to partial dissolution in citrate bicarbonate (CB) and citrate-bicarbonate-dithionite (CBD) solutions. Small amounts of Fe and Si dissolved as a result of Fe reduction in CBD, but affected <1% of the total clay mass except for the Czechoslovakian clay in which 2% of the clay dissolved. Although slightly more Fe dissolved than Si, no change in surface charge was noted. Almost no dissolution of these elements was detected in CB solution. In contrast, significant Al was detected in the CB solution, suggesting a heterogeneous dissolution mechanism. The CEC, however, was unchanged by the CB treatment. These results may be explained by the adsorption of hydrogen ions into the vacated Al3+ sites in the mineral structure. Dissolution seems to have been independent of the effects of Fe oxidation state on surface charge.

A kaolinite-rich bed (tonstein) and an associated bentonite in the upper part of Yegua Formation at College Station, east-central Texas, were formed by in situ weathering processes in a late Eocene swamp. X-ray powder diffraction, infrared spectroscopy, petrographic studies, and scanning and transmission electron microscopy not only show that dioctahedral smectite and coarsely crystalline kaolinite are the dominant minerals in the bentonite and tonstein, respectively, but that cryptocrystalline halloysite and kaolinite are localized along the weathering front (transitional zone) between the tonstein and the bentonite. As weathering progressed, the cryptocrystalline minerals gradually recrystallized to yield the coarse books and vermicular growths of kaolinite characteristic of the tonstein.

Small amounts of cristobalite, sanidine, and euhedral zircon crystals with liquid or gaseous inclusions accord with the formation of the bentonite by alteration of volcanic ash. Clinoptilolite in the lignitic layer and sandstone below the bentonite probably formed from ions that were released during alteration of the volcanic materials to smectite, but clinoptilolite in the tonstein and overlying strata appear to have formed after kaolinization of the bentonite.

Multivariate statistical analyses of geochemical, mineralogical, and cation-exchange capacity (CEC) data from a Venezuelan oil well were used to construct a model which relates elemental concentrations to mineral abundances. An r-mode factor analysis showed that most of the variance could be accounted for by four independent factors and that these factors were related to individual mineral components: kaolinite, illite, K-feldspar, and heavy minerals. Concentrations of Al, Fe, and K in core samples were used to estimate the abundances of kaolinite, illite, K-feldspar, and, by subtraction from unity, quartz. Concentrations of these elements were also measured remotely in the well by geochemical logging tools and were used to estimate these mineral abundances on a continuous basis as a function of depth. The CEC was estimated from a linear combination of the derived kaolinite and illite abundances. The formation's thermal neutron capture cross section estimated from the log-derived mineralogy and a porosity log agreed well with the measured data. Concentrations of V, among other trace elements, were modeled as linear combinations of the clay mineral abundances. The measured core V agreed with the derived values in shales and water-bearing sands, but exceeded the clay-derived values in samples containing heavy oil. The excess V was used to estimate the V content and API Gravity of the oil. The log-derived clay mineralogy was used to help distinguish nonmarine from transitional depositional environments. Kaolinite was the dominant clay in nonmarine deposits, whereas transitional sediments contained more illite.

Cementing materials in the Arahama sand dune, Japan, were studied mineralogically and biogeochemically to gain a better understanding of the cause of hardening. The cementing material is a clay-organic complex composed of noncrystalline gels and a matrix of small, poorly crystalline particles showing 14–16-Å spacings. The gel materials appear to have transformed into the poorly crystalline particles, which have a high carbon content and Al/Si ratios of 2.2 to 2.0. These particles are slightly richer in Si and poorer in Fe than the gel materials themselves. The organic portion of the complex can be removed by H2O2 treatment, leaving a noncrystalline network-structure containing a dispersed granular component. Scanning auger-depth profiles of individual particles show a high surface concentration of C and O and an increase in the Al/Si ratio with depth. The energy-intensity distribution suggests a mixture of carbon compounds having a major core-line binding energy of a hydrocarbon. The gel-cementing materials in the sand dune may have been formed from biochemical weathering products of organic matter, which subsequently controlled the formation of clay-organic complexes.

A monoclinic IIb-2 clinochlore from Washington, D.C., contrary to previous studies, is primarily a ferroan rather than a ferrian chlorite. Disorder of tetrahedral Si,Al cations is indicated because of unsuccessful structural refinements in subgroup symmetries. The true space group is C2/m. Slight ordering of Mg, Fe2+, and Fe3+ over octahedra M(l) and M(2) within the 2:1 layer (mean M-O,OH = 2.092 and 2.084 Å, respectively), complete ordering of trivalent Al into the centrosymmetric octahedron M(4) of the interlayer sheet (M-OH = 1.929 Å), and ordering of primarily divalent cations (Mg and Fe) into the two interlayer M(3) octahedra (M-OH = 2.117 Å) exist. The excess of negative charge above unity due to tetrahedral substitution of Al for Si (1.378 atoms) is compensated entirely within the octahedral sheet of the 2:1 layer.

Ordering of a trivalent cation into one octahedron in the interlayer should be universal for all stable trioctahedral chlorites. In this specimen the ordering is due to (1) minimization of cation-cation repulsion by layer offsets which provide more space around the trivalent element, and (2) energy minimization by localization of the source of positive charge on the interlayer sheet in one octahedron rather than two. In other structures or for different compositions additional factors can be important also. Most chlorites of the IIb and Ib (β = 90°) types are expected to show disorder of the tetrahedral cations. The b positioning of interlayer and layer provides no preferential driving force for concentration of Si and A1 in any tetrahedron as a consequence of the expected ordering of the interlayer cations. The monoclinic IIb-2 polytype is less abundant in nature than the triclinic IIb-4 and IIb-6 structures, because only half as many possible superpositions of layers exist that will produce monoclinic symmetry. Crystallization factors must also be important, because the IIb-2 chlorite is much less abundant than predicted by this purely geometrical argument.

Well-characterized American Petroleum Institute clay standards, source clays from The Clay Minerals Society, and other secondary minerals were used to determine the effects of U concentration, temperature, and solution composition on U-sorption properties. Uranium concentrations ranged from about 1.00 × 10−4 M to 4.00 × 10−7 M, temperatures from 5° to 65°C and solution compositions containing 0.01 M NaCl and 0.01 M NaHCO3. Silica gel efficiently sorbed uranyl carbonate anion complexes. The higher cation-exchange capacity materials most readily sorbed uranyl ions from the 0.01 M NaCl solution. Temperature increases tended to affect uranyl ion sorption adversely except when the U was present as carbonate complexes. Noncrystalline ferric oxyhydroxides sorbed uranyl ions much more efficiently than any of the secondary crystalline minerals studied. A method for accurately extrapolating U-sorption efficiencies between experimental points based on the Freundlich equation is presented.

X-ray powder diffraction intensities for many interstratified structures of mica/smectite and chlorite/smectite were calculated by changing combinations of probabilities and transition probabilities of two component layers, respectively. The calculated d-values were plotted with PMS and PSM as the axes of coordinates for mica/smectites (where M is a mica layer and S is a smectite layer). These d-values were then linked into equal d-value curves on a graph. Three equal d-value diagrams ranging from 32.5 to 24.5 Å, from 15.4 to 10.25 Å, and from 3.365 to 3.08 Å were constructed for mica/smectites. Several diagrams were also constructed for mica/glycolated-smectites and chlorite/smectites using the same techniques. PMS and PSM values of mica/smectite producing 26.8- and 12.6-Å reflections in its X-ray powder diffraction pattern were obtained from the coordinates of the intersection of the 26.8-Å line of the first diagram and the 12.6-Å line of the second diagram. The components and stacking parameters of mica/smectites and chlorite/smectites were estimated easily using these diagrams. Interstratified mica/smectites were quantified in the air-dry and glycolated states, and chlorite/smectites in the glycolated state. Stacking parameters obtained by this method agreed well with those obtained by MacEwan's method. Stacking parameters for Reichweite (R=0) and (R= 1) structures were obtained.

Clay mineralogy and petrography of the Early to Middle Eocene succession of the Dammam dome, Saudi Arabia, comprising the Rus and Dammam Formations, were studied using X-ray powder diffraction, light microscopy, and scanning electron microscopy. These formations consist of alternations of dolomite, dolomitic marl, claystone, and shale. The rocks were deposited and subjected to early diagenetic dolomitization in a shallow, coastal marginal basin characterized by rapid changes in salinity. Palygorskite occurs as interwoven fibrous mats forming fine laminae in shales and as coatings and pore-filling and pore-bridging cements in dolomitic marls. This textural evidence suggests a direct chemical precipitation, mostly post-dating dolomitization. Magnesium concentrations in presence of dolomite was sufficient for palygorskite precipitation; the necessary Si and Al were derived by dissolution of silicates under alkaline conditions. The maximum development of palygorskite was near the top of the Dammam Formation, which was deposited during a marine transgression in the Lutetian. The formation of palygorskite in marginal restricted basins in eastern Saudi Arabia took place during Paleocene-Middle Eocene time and was contemporaneous with similar occurrences in the Tertiary basins of West Africa.

The heat capacities of kaolinite (7 to 380 K) and of dimethyl sulfoxide (DMSO) intercalated kaolinite (20 to 310 K) were measured by adiabatically shielded calorimetry. The third law entropy of kaolinite, S298, is 200.9 ± 0.5 J·mol−1K−1.

The “melting point” of the DMSO in the intercalate, 288.0 ± 0.2 K, is 3.7 K lower than that of pure DMSO, 291.67 K. The heat capacity of DMSO in the intercalate above 290 K is approximately 5.2 J·mol−1·K−1 smaller than that of pure liquid DMSO at the same temperature.

Samples from initially smectite-rich Tertiary continental volcaniclastic sediment from the Deer Lodge and Big Hole basins of southwestern Montana show a general decrease in illite/smectite (I/S) expandability with increasing burial depth. The mineralogical trends in cuttings from seven wells are interrupted by discontinuities in which I/S expandability abruptly decreases by 30 to 80%. These discontinuities coincide with stratigraphic unconformities in four wells in which the stratigraphy is known. Core samples show a wide range of I/S expandabilities over short stratigraphic intervals, possibly due to composition, porosity, and permeability variations. Sericite coexists with I/S in the deep core samples. A core sample from 7958 ft (2425 m) contains an R3-ordered I/S having a nearly ideal 3:1 illite: smectite ratio, similar to the mineral tarasovite. The structure of this I/S is dominated by stacks of four 2:1-layer fundamental illite particles and small proportions of thicker particles randomly interstratified among the four-layer particles.

Well-crystallized ferrihydrite as indicated by its X-ray powder diffraction pattern and low solubility in acidified oxalate (Feo/Fet = 0.27) was formed by the oxidation of FeCl2 solution containing Si/Fe = 18 × 10−3. The crystallinity of ferrihydrites formed from the solutions containing Si/Fe > 18 × 10−3 was lowered as indicated by weaker and broader XRD lines and increased oxalate solubility. Ferrihydrites formed in the presence of silica did not give the differential thermal analysis exothermic peak between 350° and 450°C that is found for ferrihydrites prepared from the hydrolysis of Fe(III) salts. The transformation of ferrihydrite (formed at Si/Fe = 18 × 10−3) to hematite was inhibited by the presence of 1.48% SiO2 in the oxidation products.

Unmanned aerial vehicles (UAVs), which are available in our lives in many areas today, bring with them new expectations and needs along with developing technology. In order to meet these expectations and needs, main subjects such as reducing energy consumption, increasing thrust and endurance, must be taken into account in UAV designs. In this study, Backtracking search optimisation (BSO) algorithm-based adaptive neuro-fuzzy inference system (ANFIS) model is proposed for the first time to improve UAV thrust. For this purpose, first, different batteries and propellers were tested on the thrust measuring device and a data set was obtained. Propeller diameter and pitch, current, voltage and the electronic speed controller (ESC) signal were selected as input, and UAV thrust was selected as output. ANFIS was used to relate input and output parameters that do not have a direct relationship between them. In order to determine the ANFIS parameters at the optimum value, ANFIS was trained with the obtained data set by using BSO algorithm. Then, the objective function based on the optimum ANFIS structure was integrated into BSO algorithm, and the input values that gave the optimum thrust were calculated using BSO algorithm. Simulation results, in which parameters such as engine, battery and propeller affecting the thrust are taken into account equally, emphasise that the proposed method can be used effectively in improving the UAV thrust. This hybrid method, consisting of ANFIS and BSO algorithm, can reduce the cost and time loss in UAV designs and allows many possibilities to be tested.

The internal fabric of glauconite pellets has been studied by high-resolution transmission electron microscopy (HRTEM) for a better understanding of the glauconitization process. Typical “lamellae” which make up the glauconite pellets showed a spindle-like arrangement of layered crystallite packets. Three main mineral phases were detected: (1) well-ordered glauconite sensu stricto (d(001) = 10 Å) generally in the middle of the spindles; (2) a poorly ordered and undetermined layered-phase “X” with d(001) ~ 12.5 Å, usually sandwiching glauconite such that the interface between the two materials is very sharp; and (3) a noncrystalline or gel-like phase located between the lamellae. A 14-Å smectite-like phase was rarely observed at the periphery of some grains. The glauconite crystallites clearly showed characteristic growth features (e.g., growth steps), whereas the unknown phase X exhibited destabilization characteristics. A structural analysis of the pure glauconite indicates that this dioctahedral mica was present in the IMd (disordered), 1M, and, to a much lesser extent, 2M1 polytypic forms. HRTEM revealed no interlayering of glauconite with the other layered phases. Rather, it appeared to have formed by a layer-growth mechanism at the expense of the unknown phase X which apparently converted into non-crystalline matter before converting to glauconite. The precursor function of the interlamellae “gel” phase during the evolutive process of glauconitization is not understood.