Glycerol Solvation Research Articles

Direct Evidence for the Effect of Glycerol on Protein Hydration and Thermal Structural Transition

The mechanisms of protein stabilization by uncharged solutes, such as polyols and sugars, have been intensively studied with respect to the chemical thermodynamics of molecular crowding. In particular, many experimental and theoretical studies have been conducted to explain the mechanism of the protective action on protein structures by glycerol through the relationship between hydration and glycerol solvation on protein surfaces. We used wide-angle x-ray scattering (WAXS), small-angle neutron scattering, and theoretical scattering function simulation to quantitatively characterize the hydration and/or solvation shell of myoglobin in aqueous solutions of up to 75% v/v glycerol. At glycerol concentrations below ∼40% v/v, the preservation of the hydration shell was dominant, which was reasonably explained by the preferential exclusion of glycerol from the protein surface (preferential hydration). In contrast, at concentrations above 50% v/v, the partial penetration or replacement of glycerol into or with hydration-shell water (neutral solvation by glycerol) was gradually promoted. WAXS results quantitatively demonstrated the neutral solvation, in which the replacement of hydrated water by glycerol was proportional to the volume fraction of glycerol in the solvent multiplied by an exchange rate (β ≤ 1). These phenomena were confirmed by small-angle neutron scattering measurements. The observed WAXS data covered the entire hierarchical structure of myoglobin, ranging from tertiary to secondary structures. We separately analyzed the effect of glycerol on the thermal stability of myoglobin at each hierarchical structural level. The thermal transition midpoint temperature at each hierarchical structural level was raised depending on the glycerol concentration, with enhanced transition cooperativeness between different hierarchical structural levels. The onset temperature of the helix-to-cross β-sheet transition (the initial process of amyloid formation) was evidently elevated. However, oligomerization connected to fibril formation was suppressed, even at a low glycerol concentration.

Hydroxy-interlayered minerals in the Holocene paleosol on the southernmost Loess Plateau, China

The presence and formation of hydroxy-interlayered minerals in the Holocene paleosol at the Wugong profile on the southernmost Chinese Loess Plateau were investigated by examining the < 1 μm and 1–2 μm clay fractions of the 50–150 cm horizon by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Prior to the analyses free Al and Fe phases were removed by dithionite-citric-bicarbonate (DCB) extraction. XRD patterns were obtained with air-dried, Mg-saturated, Mg-saturated with glycerol solvation (Mg-glycerol) and K-saturated and heated at 110, 250, 350, 450 and 550 °C samples both before and after hydroxy-interlayered materials removal by sodium citrate extraction. The absorption bands at 3699 and 3430 cm− 1 in the FTIR spectra of both sub-fractions indicated the presence of hydroxy-interlayered minerals. The K-saturated and heated XRD patterns confirmed this by the progressive collapse of the 1.4 nm reflection to a 1.0 nm reflection. After removal of the hydroxy-interlayered materials no obvious increase of the relative XRD intensity of the 1.8 nm reflection in Mg-glycerol pattern was observed and the 1.4 nm reflection exhibited a stronger collapse to 1.0 nm after K-saturation and increasing temperature treatment. This indicated that the hydroxy-interlayered minerals in the Holocene paleosol were mainly composed of hydroxyl-interlayer vermiculite. The hydroxyl-interlayer vermiculite was formed by the polymerization of Al/Fe-hydroxy materials within the interlayer space of vermiculite. Shoulder-like reflection at 1.2 nm in the K-550 °C pattern of the 1–2 μm fraction indicated a higher degree of Al/Fe-hydroxylation in the coarse fraction than in the fine fraction, which was consistent with the lower extractable Al and Fe in the coarse fraction. The reflection at 1.38 nm in the K-550 °C pattern could be interpreted as pedogenic chlorite. Thus, transformation of vermiculite into hydroxy-interlayered vermiculite and finally into a chlorite-like mineral (pedogenic chlorite) has occurred in the Holocene paleosol on the southernmost Chinese Loess Plateau.

Report on the natural occurrence of a silica-clay nanocomposite

A natural occurrence of a silica/clay nanocomposite material was investigated by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). High-resolution images show that this nanocomposite material consists of 5–20 nm thick slabs of smectite and tridymite/cristobalite layers with coincident normals. In spite of the brittle glass-like appearance of the nanocomposite material its colloidal properties are similar to those of pure smectite but partial loss of expansion capacity was detected upon glycerol solvation. The structural relationship between smectite and silica is interpreted based on the smectite structure model of Edelman and Favejee (1940) which supposes reversed tetrahedra in the SiO4 layer of the TOT structure. This structure model explains the presence of silica impurities in bentonites used as raw material and several geological standard montmorillonites.

A simple approach to the identification of trioctahedral smectites by X-ray diffraction

AbstractA new method for identifying the trioctahedral smectites saponite, stevensite and hectorite is proposed in this study. The method is based on differences in the X-ray diffraction (XRD) patterns of the three smectites after (a) heating at 500°C for 90 min and (b) glycerol solvation of the Cs-forms of the smectites for 20 h. After heating at 500°C, well below the dehydroxylation temperature of the three smectites, saponite and hectorite re-expand upon ethylene glycol (EG) solvation, whereas stevensite layers remain collapsed. Saponite forms one-layer and hectorite two-layer complexes after Cs-saturation and glycerol solvation. Cs-stevensite displays a gradual increase ind001with increasing solvation time in glycerol vapours and forms two-layer glycerol complexes with prolonged solvation. Except for the individual Mg-smectites, the proposed method may be used to identify compositional heterogeneity that may exist in the smectites. Furthermore, it should be useful in identifying the individual trioctahedral Mg-smectites when present in mixtures, and in detecting interstratified layers of different Mg-trioctahedral smectites. Application of the method revealed that the SYnL-1 laponite (CMS Source Clay Project) is not homogeneous but consists of hectorite, stevensite and possibly mixed-layer hectorite/stevensite layers.

Pertumbuhan Material Interlayer di Mineral Lempung Smekit di Tanah Leptic Hapludert yang Berkembang di atas Ca-Bentonit di Nanggulan Kulon Progo

The objective of this study was to understand the mineralogical characteristics of the bentonite and its upper developed soil, at Nanggulan Kulonprogo. Separation and collection of clay fraction were done by fractionation on suspension at pH 10 after organic matter was oxidized using H2O2. Characteristics of clay mineral was analyzed using X-ray diffraction on parallel oriented samples after Mg saturation, glycerol solvation, or K saturation, and its following successive heating at 100°C, 300°C and 550°C. Cation exchange capacity (CEC) and the exchangeable bases were analyzed using saturation of NH4OAc 1N pH 7. Results showed that clay materials of both samples were Ca-bentonite. Comparing with clay from soil, bentonite had peak intensity of the semctite minerals and low value of CEC and exchangeable Ca. Potassium saturation caused incompletely shrinkage of the studied smectite minerals, and it was reflected by a broader peaks at 13,11 Å. The presence of these broader peaks was interpreted as a growth of interlayer materials that it may alter to smectite-chlorite intergrade minerals.

Hydroxy-interlayered vermiculite genesis in Jiujiang late-Pleistocene red earth sediments and significance to climate

To understand the paleoclimatic significance of the red earth sediments in Jiujiang, southern China, hydroxy-interlayered vermiculite (HIV) in the deposits was investigated using X-ray diffraction (XRD), chemical extraction, and high resolution transmission electron microscopy (HRTEM). The XRD results indicated that the clay mineral assemblages of the sediments are mainly illite, kaolinite, HIV, vermiculite, with minor illite-HIV mixed-layer clays. The 1.41-nm reflection did not expand after Mg saturation and glycerol solvation, but it shifted to 1.38nm and 1.20nm when the samples were heated to 350°C and 550°C, respectively. The 1.41-nm spacing showed partial collapse after K+ saturation at 80°C in association with the reinforcement of the 1.0nm reflection. Collapse of the HIV (001) spacing was related to the release of Al, Mg, and Ca from the interlayer after KCl extraction. The Al was probably present as hydroxy-Al in HIV interlayers before being released. The HRTEM image revealed 1.4-nm lattice fringes interstratified with illite 1.0nm fringes and two illite lattice fringes merged into one HIV fringe. This suggests that the HIV clays in Jiujiang soils resulted from illite weathering. The shift of a small X-ray diffraction reflection between 1.0 and 1.4nm for an air-dried and glycerol-solvated sample to 0.997nm after heating at 550°C indicated the presence of an irregularly interstratified illite–HIV mineral. The common occurrence of HIV minerals in the Jiujiang red earth sediments suggests a climate with frequent wet and dry cycles prevailed during late-Pleistocene time.

Mg and K exchange cation effects on the XRD analysis of soil clays

The changes detected by Mg‐ and K‐saturation and ethylene glycol and glycerol solvation of a modern fluvial soil from the Mississippi River floodplain can be explained by the predictable behavior of smectite and vermiculite layers of variable charge. Simulated patterns based on NEWMOD were used to identify discrete layer types and varieties of two-component mixed layered clays present. Phases detected include several two-component varieties of R0 and R1 ordered mixtures of illite, smectite, or vermiculite and minor quantities of smectite, illite, kaolinite, chlorite, and clay-sized quartz. Major differences in the coarse (<2 µm) and fine clay (<0.2 µm) fractions are associated with smectite/illite in the Mg-treated material that appears to be illite/vermiculite in the K-saturated sample. A high-charged smectite or vermiculite is the most abundant expandable material in this soil. Observed differences between Mg and K saturation illustrate the general complexity of the varieties of expandable layer sequences in soils, which can be identified by the application of the approach described in this paper.

Characterization of kaolin/smectite mixed layer mineral in paleudult of Java Island

In a Paleudult of Java Island, there was a clay mineral indicating a mixed layer mineral which gave 15.51 A peak (in the range of 14.63 A and 16.37 A) on Mg 2+ -air dry and a 20.55 A peak on Mg 2+ -glycerol solvation. On K - -saturation, the mineral showed an 11.87 A peak and this peak was continuous to 7.53 A. Furthermore, on sequential heating, the peak gradually shifted and finally shifted completely to 10.05 A at 550°C in X-ray diffraction (XRD). A peak of 7.53A was also observed in both Mg 2+ - and K + -saturated clays which disappeared after heating at 550°C. The objective of this study was to investigate the characteristics of this mineral. The 060 peak was 1.50 A and suggests the dioctahedral smectite. The Greene-Kelly test on the clay sample suggests beidellite. Formamide solvation that caused a swelling of the 7.53 A peak to 10.05 A suggests the presence of halloysite. The 5M NaOH treatment resulted in a collapse of the 7.53A peak and remained at a sharp peak of 15.50 A (in Mg 2+ -saturated clay). The presence of halloysite was also supported by a SiO 2 /Al 2 O 3 molar ratio of NaOH extractable materials. The NaOH treatment also resulted in an increase of the 11.87 A peak (in K + -saturated clay) to 13.49 A. According to the mineralogical and chemical properties of the clay sample we consider that the mineral is halloysite/beidellite mixed layer mineral.

Effect of Heating on Swelling and Dispersion of Different Cationic Forms of a Smectite

AbstractThe effect of heat treatments on the swelling, dispersion, particle charge and particle aggregation of Li-, Na-, K-, Mg-, Ca- and Al-Wyoming bentonite was investigated. Before thermal treatment, unheated (25 °C) Li-, Na- and K-clays showed increased d001 spacing on glycerol solvation and dispersed spontaneously in water. Mg-, Ca- and Al-clays did not disperse spontaneously in water, but the d001 spacing increased upon glycerol solvation. After heating at 300 °C or above, none of these clays dispersed spontaneously. However, swelling varied with the type of cation and the temperature of heating.The results generally suggested that swelling and dispersion of homoionic Wyoming bentonite after heating at various temperatures depended upon the nature of bonding between clay particles and the cations. Enhanced swelling and dispersion of clays indicated the more ionic character of the cationic bonding than cases where heating resulted only in swelling, with polar covalent bonding of cations to clay surfaces allowing limited hydration. It is also suggested that, when both swelling and dispersion as a result of thermal treatment are absent, a covalent bond is formed between cation and clay surface.Thermal treatment apparently affects the bonding in different ways. It appears that the smaller cations (ionic radius &lt;0.7 Å) Li, Mg and Al migrate to octahedral vacant sites and form covalent bonds after heating at 400 °C; this drastically reduces the negative charge. This process for Li-clays occurred even at 200 °C. The larger cations (ionic radius &gt; 0.9 Å) Na, K and Ca apparently did not migrate into the lattice sites after heating to 400 °C; a high proportion of them were exchangeable. The data for exchangeable cation, particle charge and clay particle size were consistent with the postulated effect of the nature of cationic bonding upon swelling and dispersion properties.

Polymeric complex membranes for olefin/paraffin separation

AbstractSemi‐crystalline polyethylene (PE), rubbery silicone rubber (SR) and glassy poly[(l‐trimethylsilyl)‐l‐propyne] (PTMSP) were modified for olefin/paraffin separation. The polymers were first grafted with the acrylic acid (AA) and then incorporated with silver ions for forming the complex membranes such as PE‐g‐AA‐Ag+, SR‐g‐AA‐Ag+ and PTMSP‐g‐AA‐Ag+ The complex membranes were activated by glycerol solvation and subsequently showed high selectivity in olefin/paraffin separation. The silver ion distribution, the kinetics of olefin binding to PE‐g‐AA‐Ag+, the gas permeation properties and the sorption behaviors were studied. A novel dry complex membrane for olefin/paraffin separation based on AgClO4 complexing with PTMSP main‐chain was also studied.

Beidellite in E Horizons of Northern Idaho Spodosols Formed in Volcanic Ash

AbstractWhile soils formed in tephra are typically dominated by poorly crystalline clay minerals, the occurrence of smectite in E horizons of podzolized soils (Spodosols) has been well-documented. We have observed a well-crystallized smectite mineral dominating the clay fraction of E horizons in tephra-derived soils of northern Idaho. This study was initiated to examine properties and distribution of this mineral along a developmental sequence of high-elevation, forested Spodosols formed in 6800-yr-old Mazama tephra. Three soils exhibiting strong, moderate, and weak E horizon development were sampled along an elevational and climatic gradient. The smectite mineral was identified as beidellite based on expansion and layer charge characteristics. Heated, Li-saturated samples from the most strongly developed E horizon exhibited relatively complete expansion to 1.8 nm with glycerol solvation and mean layer charge was calculated to be 0.44 molc/formula unit using sorption characteristics of alkylammonium ions. Apparent crystallinity and relative abundance of the beidellite in clay fractions decrease with decreasing E horizon development. The more poorly crystalline beidellite is associated with a non-expansive 1.4-nm mineral with considerable Al-hydroxy interlayering. Beidellite was not detected in underlying glacial drift or in a thin layer of 200-yr-old ash that mantles these soils, suggesting it is not inherited from these materials. Rather, our results indicate that beidellite forms in these soils in an environment characterized by low pH and a large flux of organic metal-complexing agents.

Layer charge of expandable 2:1 phyllosilicates in selected parent materials of some Canadian soils

We investigated the nature of the layer charge of the different expandable 2:1 phyllosilicates present in glacial till, marine sediment, beach sand, loess, weathered sandstone and acid shale parent materials of selected soils from the arctic, alpine and interior plateau regions of Canada. Detailed characterization of 2:1 clay minerals, using the layer charge, was done by intercalation of the clay fractions with different chains (nc = 6 to 18) of n-alkylammonium cations (AC).Results indicated that AC were able to detect a mixture of smectite and vermiculite that was not detected by previous studies, using the glycerol (GLY) and ethylene glycol (EG) solvation techniques. The mean unit cell layer charge [in mol(+)/Si,Al)4O10)] varies from 0.30 to 0.39 for the smectite and from 0.71 to 0.74 for vermiculite. Vermiculite from the beach sand is trioctahedral in which most of the charge is located in the tetrahedral sheet, while vermiculite in the weathered sandstone is dioctahedral in which part of the charge originates from the octahedral layers. The presence of smectite, associated with the weathering of chlorite and an expanding component associated with the degradation of biotite, was also observed. Key words:n-alkylammonium cations, mean layer charge, 2:1 phyllosilicates

K‐fixing phyllosilicates in soils: the role of inherited components

SUMMARYK‐fixing potential of 29 illite/smectite mixed‐layer minerals, covering a broad range in layer ratios and stacking arrangements, has been investigated utilizing X‐ray diffraction as the principal investigative tool. Samples were derived from a borehole core transecting Permian sedimentary rocks. In 93% of all samples, K+ was retained against replacement with Mg2+ from a 1 M MgCI2 solution in an average of 33% of the smectitic interlayers, defined via expansion to 1.7 nm upon ethylene glycol solvation after Mg‐saturation. This non‐ideal smectite behaviour points to a vermiculite‐type layer charge. Ordered structures fixed on average 20% more K than did random ones, but results were widely scattered. The Greene‐Kelly test revealed predominantly tetrahedral substitution, intercalation with dodecylammonium chloride molecules a high interlayer charge density in samples with a high K‐fixing capacity.The findings have implications in two fields: in pedology, soils developed from thermally altered sedimentary rocks may inherit a considerable potential for K–fixation; in mineral identification, interlayers in illite/smectite interstratifications fully expanded to 1.7 nm upon ethylene glycol solvation despite their vermiculite–type layer charge. Glycerol solvation provided equally inconsistent results, while dodecylammonium spacings seemed to correlate reasonably well with interlayer charge density characteristics.

Identification of vermiculite by transmission electron microscopy and X-ray diffraction

AbstractThe expandability of K-depleted biotite and natural vermiculite was studied using transmission electron microscopy (TEM) and X-ray diffraction (XRD). K-depletion in layer-silicates was achieved by treating ultrathin sections with 0·1 m CaCl2 and BaCl2 solutions. The natural sample of biotite, which by XRD revealed no expandability on ethylene glycol or glycerol solvation, displayed 10–15% expanded layers when viewed by TEM after alkylammonium intercalation. The proportion of expanded layers increased after CaCl2 treatment. XRD of vermiculite samples revealed two sets of expandable interlayers after alkylammonium treatment, corresponding to two types of particles with different layer structures observed by TEM. Identification of vermiculite by TEM based on basal spacings is reliable with alkylammonium treatment. Intercalation of alkylammonium ions into the interlayers of vermiculite improved the degree of stacking order of the 2:1 layers.

Effects of Layer Charge, Charge Location, and Energy Change on Expansion Properties of Dioctahedral Smectites

AbstractExpansion properties often homoionic smectites that differed in amount and location of layer charge were examined by X-ray powder diffraction analysis at various relative humidities, or after glycerol or ethylene glycol solvations. Except for K-samples with glycerol solvation, and Na- and Ca-samples with ethylene glycol, differences in the basal spacings are observed in samples having similar layer charge. These results show that the basal spacings are larger when the layer charge is located in octahedral sites than when it is in tetrahedral sites. This suggests that expansion is due to the combined effects of the charge location and amount.The effects of layer charge magnitude and location on expansion were represented by an energy change (expansion energy: ΔEr) during the hydration and solvation processes. Plots of basal spacings versus ΔEr show a reasonable relationship; the spacings generally decrease stepwise as the value of ΔEr increases. The basal spacings of K-samples with glycerol solvation, Na-saturated and K-saturated samples at 100% RH are apt to contract stepwise with increasing value of ΔEr. For these samples, the figures showing the relationship between each expanded phase and the charge characteristics are obtained from the isoquants of ΔEr, given the boundary of the expanded phases. A behavior test using these figures may be combined with the Greene-Kelly test to estimate the amount and the location of the layer charge of common smectites.

High-Charge Smectite in Spanish “Raña” Soils

AbstractIn a study of “rana” soils of central Spain, hydroxy-interlayered 2:1 clay minerals were identified in the upper horizons and high-charge smectite in the lower horizons, with kaolinite the most abundant phyllosilicate. The high-charge smectite showed a basal spacing of 18 Å on Mg-saturation and glycerol solvation and 10 Å on K-saturation and air-drying. It is concentrated in the coarse fractions and appears to be basically a beidellite in the fine-silt fractions and a montmorillonite in the clay fractions. Pre-existing illite was probably transformed into hydroxy-interlayered 2:1 clays in the surface horizons, whereas high-charge smectite formed in the deeper horizons. These minerals, which were apparently not stable in the existing soil conditions, were the first stage in the degradation process of illite. The stable mineral in these soil profiles was kaolinite.

砥部陶石のＬｉ‐トスダイト

Tosudite specimens occurring as monomineralic veinlet and as a prominent constituent of pottery stone in the Rokuro deposit, Ehime Prefecture, have been examined by X-ray, chemical, thermal and infrared methods. The basal reflections are very close to an exact integral series : the mean value of d(001) is 29.41 A in natural state, and expands to 32.10 A by glycerol solvation after saturation with Mg. The value of d(060) is 1.489A. Taking the exchangeable cations into consideration, a reasonable structural formula is given as follows; chlorite layer : [Al1.99Fe3+0.03 Mg0.01Li0.84K0.15Na0.01(NH4)0.03](OH)6·Al2.00(Si2.89Al1.11)O10(OH)2, smectite layer : [Al0.12Mg0.01K0.01(NH4)0.01]·5.0H2O Al2.00(Si3.59Al0.41)O10(OH)2.The chlorite layer is close to an ideal cookeite composition. However, small amounts of K incorporated into the interlayer octahedral sheet seem to be essential to construct the chlorite layer. Interlayer Al in the smectite layer is presumably combined with hydroxyl (hydroxyl Al ion), which is correlated to the distinctive endothermic reactions at 350 and 410°C. The infrared OH absorption bands and the refined z-parameters of atomic planes are also discussed in regards with accommodation of K ions in the structure of Li-tosudite.

スメクタイトのイライト化に伴う膨張層の変化

The expansion properties of expandable layer in illite/smectite randomly interstratihed clay minerals (I/S) occurring in diagenetic alteration have been directly evaluated by behavior tests (expansion tests) using X-ray diffractometry. The behavior tests have been performed after following preparations : (1) ethylene glycol solvation ; (2) K-saturation and ethylene glycol solvation ; (3) Li-saturation, heating and glycerol solvation (Greene-Kelly test). The results of behavior tests for glycolated samples (unsaturated and K-saturated samples) suggest that smectite layer in I/S convert into high-charged one with increasing percentage of illite layer (I%). The results of Greene-Kelly test indicate that the expandable layer in I/S at early stage of illitization possesses both tetrahedral and octahedral charges, and that the amount of smectite layers having tetrahedral charge decrease with increasing I%. From the results of Greene-Kelly test, it is considered that the smectite layers having tetrahedral charge convert into illite layer selectively. The results of these behavior tests suggest that tetrahedral substitution of smectite layer is more effective in the illitization process than increasing the total layer charge.

Hydration states in interlayer of hydromuscovite.

Hydration states of hydromuscovites under conditions of 80% and 50% R. H. and glycerol solvation after saturation with various kinds of cations in the expandable interlayers were examined by means of Fourier transform analysis. At 80% R. H., Ca-saturated specimens showed one- and two-layer hydration states of expandable layer and the ratios of two-layer to one-layer hydration states decrease with increasing the proportions of mica layer components. At 50% R. H., Ca-saturated specimens indicated a decrease in two-layer hydration and an increase in one-layer hydration as compared with those of the specimens at 80% R. H. Glycerol solvated complexes of Mg-saturated specimens showed that the specimens contain one-layer glycerol complexes with spacing of about 12.5A. These hydration states of the hydromuscovites are different from those of smectites and expandable layers of regularly interstratified mica/smectites, and it is considered to be due to their high layer charge in expandable layer.

Transitional Vermiculite‐Smectite Phases in Aqualfs of Southwestern Ohio

AbstractThe clay mineralogy of two Aqualfs occurring on the Illinoian till plain of southwestern Ohio was investigated in order to (i) determine the clay mineral distribution with depth, (ii) examine the clay mineral weathering sequence, and (iii) identify the 2:1 mineral species in which hydroxy interlayers had formed. Despite the presence of multiple parent materials, no obvious discontinuities in clay mineralogy were observed. A weathering sequence involving the transformation of clay mica to vermiculite to low charge vermiculite/high charge smectite occurred. Alkylammonium ion exchange data indicated that weathering created a heterogeneous charge distribution in the 1.4‐nm (expandable) mineral phase resulting in mixed low‐and high‐charge interlayers. The low‐charge interlayers readily formed bilayer complexes with ethylene glycol (1.7 nm), and also accommodated double layers of glycerol (1.8 nm) when the mean layer charge was &lt;0.65. Reductions in layer charge were correlated with the oxidation of octahedral Fe(II) and the expulsion of K and Mg from the mineral structure. The expansion of 2:1 layer silicates in horizons near the soil surface was restricted as a result of Alhydroxy interlayering. After interlayer materials were removed with boiling 0.33 M Na citrate, the previously interlayered minerals exhibited x‐ray diffraction effects following Mg saturation and ethylene glycol and glycerol solvation that were indicative of vermiculite.