Bangladesh has been divided into 30 Agroecological Regions (AEZs) and the applied agricultural research has currently been conducted on this basis. In context of the lack of enough information on mineralogy on the AEZ basis, an attempt has been taken to study mineralogy of important soils from all AEZs of Bangladesh in order to provide basic information for applied research. As a part of this attempt, the mineralogy of soils from three representative soil series of AEZ 11, High Ganges River Floodplain, has been reported in this paper. The clay content of the surface soils ranged from 8.9 to 30.4% and the texture was mostly silt loam. The 2-20 gm fraction was found to dominate over other fractions in all soils. This fraction was composed mainly of quartz, followed by mica, plagioclase and chlorite. Mica was the predominant mineral in the <2μm clay fraction followed by smectite in seven soils and by chlorite in five soils. The soils were uniformly grouped into three types depending on the smectite content in the <2μm clay fraction. The impact of mineralogy on the inherent potentiality of soils regarding crop production has been discussed.

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Both refluxing reaction under atmospheric pressure and hydrothermal reaction underautogenous water vapor pressure of two kinds of starting slurry with the initial molar ratio Na: Zn: Li: Si=0.7: 5.4: 0.6: 8.0 and 1.4: 5.4: 1.2: 8.0 made from Zn-Si homogeneous precipitates, lithium fluoride and sodium hydroxide successfully have yielded Zn-hectorites containing Zn²⁺ instead of Mg²⁺ in the trioctahedral sheets. Zn-hectorites have expansion of the basal spacing (d₀₀₁) by the treatment with ethylene glycol on powder X-ray diffraction (XRD) patterns, and characterized by Zn-O vibration in the around 660-670cm^-1 on fourier transform infrared spectrometer (FT-IR) spectra, peaks assigned to Zn2p on X-ray photoelectron spectrometer (XPS) spectra and thermal dehydroxylationat lower temperature on thermogravimetry and differential thermal analysis (TG-DTA). It hasalso clarified that Zn-hectorite synthesized by hydrothermal reaction under autogenous water vapor pressure is relatively large massive particles and has a larger CEC, although it has lower MB adsorptive ability compared to a commercial Mg-hectorite as reference.

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Allophane as a poorly ordered aluminum silicate is known to have lower tolerance to alkaline condition than layer silicates have, and easily dissolve completely under higher alkali concentrations. However, changes in structure and dissolution mechanism under dilute alkali concentrations are not clear. In this research, we examined interaction of allophane with dilute NaOH solutions (<pH12) with pure nano-ball allophane samples obtained by using less than 0.2μm fraction from inner part of pumice grains. The pumice grains were collected from two sites of Japan, and the separated samples were KyP (Si/Al=0.67) and KnP (Si/A1=0.99). Dissolution kinetics of Si and Al were analyzed by dividing dissolution process as two steps: first rapid dissolution step within 12 h and following slow step after 12 h. At the rapid step, dissolution rate of Al were higher by twice than that of Si for KyP, but for KnP, the both were comparable. The dissolution rate of Si was comparable between the two samples. Si/Al ratio of dissolved materials at the step was smaller than that of untreated sample for KyP, but was greater than that of untreated sample for KnP. These indicate Al of the fundamental allophane structure, imogolite sheet, is susceptible to hydroxyl attack, and in KnP structure, accessorily attached Si prevented hydroxyls to approach the site. Infrared spectra also showed more dissolution of the fundamental sheet of KyP at the rapid step. From the chemical structure of nano-ball allophane, the most susceptible part of the fundamental sheet is considered to be the pore region where many Al are exposed as broken edge.

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Shales in the upper Cretaceous-lower Tertiary in Egypt including the middle Campanian Qusseir Formation, the late Campanian-early Maastrichtian Duwi Formation, and the Masstrichtian-Danian Dakhla Formation show variable distribution of clay minerals. Duwi shales have higher smectite (85%) and lower kaolinite contents (15%) compared to Qusseir and Dakhla shales that have higher kaolinite (65 and 45% respectively) and lower smectite contents (35 and 55% respectively).
Chemical analyses indicated that these rocks were derived from the same source, the Pre-Cambrian igneous rocks located in the south and southern east of Egypt, and there is no relation between clay minerals distribution and sea level changes and depositional environments. The change in the clay mineral assemblage is attributed to climatic changes. Duwi shales are formed under and to semiarid conditions while variegated and Dakhla shales are formed under humid and tropical conditions. Therefore, the climate changed from tropical to and and then back to tropical during the upper Cretaceous-lower Tertiary in Egypt.

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Kaolinite undergoes a phase and structural change on heating. In this paper we report the growth characteristics of mullite, and it's changes in structural parameters by analyzing with help of Rietveld technique. The results show that crystallization of mullite increases with increase of temperature upto 1550°C. X-ray diffraction analysis indicates mullite formation in kaolinite takes place in two steps. The crystal parameters (a, b, c), crystal size, strain change significantly during these two steps.

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A paper sludge ash was subjected to NaOH hydrothermal condition. The component minerals of this modified paper sludge ash (MPS) were NaP1-type zeolite, gehlenite, talc, quartz and anatase, and their contents determined by standard addition method with X-ray diffraction measurement were 42.5, 20.5, 4.1, 3.0 and 1.3 mass%, respectively. The 28.5 mass% as the rest of MPS contents was amorphous calcium aluminosilicate hydrate (CASH), which was probably formed from Ca in paper additives, Al in water-clarifying reagent and Si in water glass. As a result of Pb adsorption experiments, the maximum adsorption on MPS was 20.58 μmol g^-1, which was higher than those on pure mineral species such as NaP1 and gehlenite. It was thought that the large adsorption of MPS was owing to an excellent adsorption of CASH in MPS. The molecular orbital calculation supported a speculation that the Pb adsorption on CASH was principally specific one with which silanol groups were concerned.

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The alteration mechanism of biotite in granitic rock caused by crustose liche “Porpidia” was investigated by means of X-ray diffraction, optical microscope, EPMA and electron microscope with EDX.
Vertical thin sections of lichen-rock interface were observed by a scanning electron microscope to make clear the physico-chemical phenomenon caused by lichens. The contact surfaces between lichen and a biotite were physically observed with this section, and were further investigated chemically by EPMA. As a result, physical destruction of biotite grains by lichen thallus was observed, and the formation of iron oxide or hydroxide was recognized.
The chemical compositions of some parts of the biotite crystal were analyzed by EPMA, such as altered parts closed to lichen thallus, altered parts far from lichen thallus and fresh parts. Consequently, comparison of the different parts revealed increase in Si0₂ content on one hand and decrease in FeO and K₂O on the other hand from the fresh biotite crystal throughout the licheni alteration. Due to the lower solubility of Si0₂ and higher solubility of Fe₂O₃ and Al₂O₃ from minerals under strong acid condition, which is formed by lichen thallus, it seems that Si⁴⁺ content in tetrahedral site is increased by cation exchange. Also due to the low pH and activity of high molecular weight polymers, the possible weakening of the iron-xygen bonds will lead to the dissolution of Fe ³⁺ ions. Consequently, it is likely that, due to the increasing negative charge of biotite layers with dissolutio of Fe ³⁺, dissolution of K⁺ will be disturbed. Vermiculite-like minerals in biotite formed with the actio or effect of lichen were identified by quantitative chemical analysis as wt% of oxides and calculation of structural formulae on the basis of 22 oxygen atoms per unit cell.

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The adsorption of a cationic metal complex, [Ru (phen) ₃] ²⁺ (phen=1, 10-phenanthroline), onto a mica surface from its aqueous solution was investigated. An attention was focused on the effect of molecular chirality on adsorption behavior. The saturated adsorption was determined to be (1.7±0.1)×10^-6 and (1.3±0.1)×10^-6 mol g^-1 for the racemic mixture and the Δ-or Δ-enantiomer, respectively. When adsorption was made from a partially resolved solution of [Ru (phen) ₃](ClO₄) ₂, the increase of enantiomeric excess was observed in a supernatant with the progress of adsorption. The results indicated that [Ru (phen) ₃] ²⁺ was adsorbed as a racemic pair rather than as an enantiomeric pair. Atomic force microscope observation showed that the surface remained smooth when a mica surface was in contact with an aqueous solution of racemic [Ru (phen) ₃](ClO₄) ₂, while it changed from a smooth surface to rough one for the Δ-enantiomeric solution. The change was interpreted in terms of the formation of the compact bimolecular layer for the racemic mixture, while a rough multilayer adsorption layer was formed for the enantiomer.

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The flocculation values of Cs-and Mg-montmorillonites were estimated by the relative turbidities of their suspensions in the various concentrations of CsCl and MgCl₂ solutions at pH 8.0 after each standing for one day. The outline of result is as follows:
The value of Cs-and Mg-montmorillonite was about 5×10^-3 and 2.5×10^-4 mol L^-1, respectively. Both the Cs-and Mg-montmorillonites should be formed the thin-platy flocs only composed of the “face-to-face” association based on a scheme by Van Olphen (1991). While the montmorillonites saturated with univalent cations were more hydrophilic than the montmorillonites with divalent cations, the Cs-montmorillonite was hydrophobic compared with the Na-montmorillonite of which hydration degree was very high.

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The ultra thin films of fragile specimens for high-resolution transmission electron microscopy (HRTEM) observations can be successfully prepared by our simple preparation technique. At first, the specimens are impregnated with a diluted epoxy-resin (ethanol-soluble) to prevent their breakdown. Chips are made of the impregnated specimens, and these are polished. The polished chips and glasses are adhered together using an adhesive wax at ca. 70°C. The adhered chips are thinned and polished, and they form petrographic thin sections. Mo-grids are attached onto the selected areas in the thin sections for HRTEM observations using an epoxy adhesive. Only Mo-grids attached to the selected areas can be detached from the thin sections in hot water ca. 70°C. The ultra thin films are made by thinning the Mo-grids via argon ion milling.

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