Recognizing mineralogy and geochemistry of the clay minerals is very important in order to utilize these deposits in ceramic manufacturing heavy and lightweight ceramic clay products. The objective of the study was to find mineralogical and geochemical characteristics of El-Minya clay deposits. El-Minya clay deposits are Middle Eocene (Lutetian) in age belonging to the Qarara Formation. The clay fractions were determined using X-ray diffraction analysis and were composed mainly of montmorillonite and kaolinite with minor illite. The crystallinity index measured for montmorillonite revealed that it was well crystallized, whereas that measured for kaolinite ranges from well crystallized to slightly disordered. The morphology of the clay particles was determined using a scanning electron microscope (SEM) which revealed that montmorillonite exhibited particles with regular outlines that appeared crushed edges as well as thin webby slightly crenulated flakey aggregates. Kaolinite, on the other hand, appeared as flakes with poorly developed hexagonal ragged outlines crudely seen, and as verm composed of books arranged face-to-face. These books were cracked by ribbons or shades of filamentous montmorillonite. The index of compositional variability (ICV) used to deduce the source rocks and its ratios indicated that, most of the samples were accumulated in cratonic environments and are compositionally mature. The chemical index of alteration (CIA) was proposed as an indication of the chemical weathering of the source rocks implying extreme weathering of the original source. Tectonic settings showed that all samples were in the oceanic Island Arc.

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A detailed analysis was undertaken of the X-ray photoelectron spectra of the three polymorphs of Al_2Si_2O_5(OH)_4; kaolinite, dickite, nacrite plus the related mineral halloysite. Comparison of the spectra was made based on the chemical bonding and structural differences in the Al- and Si-coordination within each polymorph. The spectra for Si(2p) for all four polymorphs are nearly identical, consistent with the fact that all the Si atoms are in 4-fold (tetrahedral) coordination, whereas the binding energies for Al(2p) vary slightly depending on the type of polymorph and the corresponding change in the stacking order of the layers. The overall shapes of the O 1s peaks observed in the four polymorphs are similar. Theoretically the ratio of oxygen atoms versus oxygen in hydroxyl groups is 5:4 (55% vs 45%). For all four polymorphs the observed values are between 53 and 58% for the oxygen atoms and 38 to 45% for the oxygen atom in the hydroxyl groups. The lower-VB spectra for the kaolin polymorphs are similar to those of α-SiO_2 in terms of binding energies, but appear 〜2 eV higher than that for α-Al_2O_3. Compared with O 1s peaks, the lower VB peaks are considerably broader (〜3-4 eV FWHM), and therefore, detailed structures cannot be resolved. Nevertheless, this difference implies that the bonding character for the kaolin polymorphs is more covalent than that of α-Al_2O_3, but similar to that of α-SiO_2.

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Fine crystals of hectorite-like layered silicate formed using hydrothermal reactions on monodisperse spherical silica particles with diameters of 0.2, 0.6 and 1.0 μm. The reactions were performed in a colloidal spherical silica suspension with lithium and magnesium ions under alkaline conditions at 373 K in a rotating Teflon-lined autoclave at the LiF:MgCl_2:SiO_2 molar ratio of 0.21:0.8:8.0. The grain size distributions were quite uniform irrespective of the silica size in the initial mixtures, as a result of the high rate of heterogeneous nucleation reaction than that of the homogeneous nucleation. The amount of a cationic surfactant that was intercalated tended to be large when the grain size of the silica spheres was small, while the negative layer charge of the hectorite-like silicate was same extent.

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Novel cationic Ga(III)phthalocyanine (hydroxo[tetrakis(N,N,N-trimethylanilinium) phthalocyaninato] gallium(III), [Ga^<III>(TMAPc)(OH)]^<4+>) was synthesized and its adsorption and photochemical behavior on clay were investigated. Ga^<III>(TMAPc)(OH) adsorbed on the clay surface without an aggregation at high density conditions. The fluorescence quantum yield and excited lifetime of Ga^<III>(TMAPc)(OH)^<4+> on clay was 0.33 and 2.1 ns at 0.05% vs. CEC, respectively. Photo-oxygenation reaction sensitized by Ga^<III>(TMAPc)(OH)^<4+> on clay was examined. Cyclohexen-2-ol and 1,2-dichlorocyclohexane were obtained as major products. Because the Size-matching rule suppresses a molecular aggregation, Ga^<III>(TMAPc)(OH)^<4+> had photochemical activity on the clay surface.

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