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 ten soils consisting of nine representative soil series of AEZ 12, Low Ganges River Floodplain, has been reported in this paper. The clay content of the surface soils ranged from 18.6 to 35.7% and the texture was mostly silt loam. The 2-20μm silt fraction was found to dominate over other fractions in almost all soils. This fraction was composed mainly of quartz, followed by mica, plagioclase and chlorite. Mica and smectite were predominant minerals 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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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 ten soils from seven important soil series of AEZ 26, High Barind Tract, has been reported in this paper. The soils were slightly acidic in nature, had moderate to high amounts of clay, and the texture was medium (silt loam) to heavy (silty clay). The 20-53μm fraction was found to dominate over other fractions in most soils. The 2-20μm fraction was composed mainly of quartz, followed by mica, plagioclase, K-feldspar and chlorite. Mica was the predominant mineral in the <2μm clay fraction followed by kaolinite. The interstratified minerals of kaolinite and smectite and of mica, vermiculite and smectite were present indicating the highly weathered nature of these soils. The impact of mineralogy on the inherent potentiality of soils regarding crop production has been discussed.

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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 ten representative soil series of AEZ 28, Madhupur Tract, has been reported in this paper. The soils were acidic in nature, had moderate to high amounts of clay, and the texture was medium (silt loam) to heavy (clay). The 2-20μm silt fraction was composed mainly of quartz, with small amounts of mica, plagioclase, K-feldspar and chlorite. Mica, kaolinite and the interstratified mineral of kaolinite and smectite were the predominant minerals 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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Samples of Egyptian glauconitic material from El Gidida area were investigated. The characterization study included the mineralogical and chemical composition, crystal morphology, surface area and porosity. The effect of heat treatment and acid activation on the surface area, pore volume and microporosity of glauconitic clay was also investigated. Data obtained by using Scanning Electron Microscope (SEM), X-ray diffraction (XRD), X-ray Fluorescence (XRF), and Infrared (IR) spectroscopy, reveal that the studied glauconitic material is di-octahedral with an iron-rich illite-smectite mixed layer composed of a range of expandable layers (<10 to 40%), in addition to variable percentages of kaolin and quartz. As the relative amounts of kaolin and quartz increased, illite-smectite mixed layers decreased. Low K₂O content in glauconitic material is related to the composition of the parental glaucony mineral phase as well as to destabilization of glauconite. Morphologically, glauconite pellets consist of spheroidal aggregates of very fine particles, arranged parallel to each other, and separated by debris. However, many of the platelets are bent and curly, generating numerous mesopores. The surface area and pore volume ranged between 80-147m²/g and 0.164-0.341cm³/g, respectively. Details of the above characterization studies are given in this paper.

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Sixteen profiles of alluvial soils of Vietnam were collected throughout the country and subjected to clay mineral analysis. Alluvial soils from different river systems/agro-ecological regions had different clay mineralogical compositions due to differences in sediment sources. Mica and kaolinite were found to be predominant clay minerals in alluvial soils. Other major minerals detected were vermiculite, smectite, chlorite, and the mica/vermiculite/smectite-mica/smectite mixed-layer mineral, depending on the river systems. The clay mineralogical composition was remarkably similar within soil units belonging to the same river system and in a profile. However, the clay mineralogical composition greatly varied with river systems; therefore, the regional variation existed and was mainly controlled by the mineralogical features of the sediment sources. Mica was found to be altered to mixed-layer minerals in some soils under specific conditions. The soil quality was assessed from the viewpoint of inherent potentiality based on the type and amount of clay minerals as plant-nutrient sources. Alluvial soils distributed in the Red River and Mekong River systems were evaluated to be in the high level of inherent potentiality. Those from the Trakhuc River and Ba River systems were classified to have low inherent potentiality, while those from the remaining ones were to be at an intermediate level.

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The clay-mineralogical characteristics were examined in two Yellow Brown Forest soils distributed in the hilly mountain area neighboring the eastern area of Fukui plain, Central Japan. The subsoil in one of the two soils was the buried horizons considered to be the paleosol. The results were summarized as follows: In those two soils, chlorite-vermiculite intergrade was predominant in the clay fractions, and the chlorite contents were increased in the surface soils, which were characterized by the Yellow-Brown Forest soils. The presence of chlorite-vermiculite intergrade accompanied by small amounts of chlorite and mica minerals suggested that they were influenced by the eolian dust transported from the Asian continent. Halloysite was found in the clay fractions of those soils and was derived from the autochthonous material which is the weathered tuffaceous rock. Gibbsite derived from the autochthonous material was also present in the clay fractions, and its content was especially high in the KZP soil.

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In order to predict the effect of acid precipitation on building stone, artificial chemical weathering of polished plates of Muroto Gabbro from Kochi, Shikoku Island, Japan, was conducted. An improved Soxhlet extraction apparatus was used with distilled water and HNO₃, H₂SO₄ and HCl solutions at pH 4 at 55°C for different periods of time up to 780 days. The gabbro was composed mainly of olivine (Fo₆₆Fa₃₄), plagioclase (Ab₃₃An₆₆Or₁), and clinopyroxene (En₄₇Fs₁₃Wo₄₀). Morphological and chemical changes of each mineral surface were studied by SEM, EPMA and optical microscopic techniques. Alteration products were collected from the surface of each mineral on the polished plates by hand picking and examined using XRD. The leached sample solutions were analyzed for major and minor elements using ICP-AES, ICP-MS and ion-chromatography.
It is evident that olivine changed into smectite, chlorite and talc by exposure to the various acid solutions used in the experiment. Smectite appeared to be formed from plagioclase during the artificial chemical weathering. However, altered products from clinopyroxene were not detected. Molar ratios of each element in the leached solutions to those in the fresh gabbro varied depending on the experimental period. The ratios of elements such as Mg, Mn, Fe, Ni, Zn and Co, which reflect the dissolution of olivine, were relatively high. Similarly, the ratios of Ca, Na, Sr, Ce, Sm and La, which reflect the dissolution of plagioclase, were relatively high. It seems, therefore, that olivine and plagioclase are easily weathered. It was also estimated from the molar ratios that the reactivity order of the acid solutions for olivine and plagioclase is H₂SO₄, HNO₃ and HCl.

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