A new approach was performed in order to obtain crystallographic data such as lattice constants of crystalline phases and lattice orientation relationship among them, which compose mineral textures in small area of 10-100 μm diameter. The principle of the technique is based on a single crystal X-ray diffraction method, and specimens examined by an optical microscope, SEM, EPMA, etc. can be available without separations. By this method, we can analyze mineral textures not only by chemical or morphological aspects but also from a crystallographic point of view. Main features of the system stand on the use of one dimensional cylindrical PSPC combined with automated small three-circle goniometers and development of new softwares for obtaining X-ray diffraction peaks from small areas and for analyzing them. Some applications of this method are also reported.

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Ion exchange experiments between ilmenite solid solution (Fe²⁺, Mn²⁺, Mg)TiO₃ and 1 molal aqueous (Fe²⁺, Mn²⁺, Mg)Cl₂ solution were carried out using standard cold-seal type pressure vessels at 600°C and 1000kg/cm². The ion exchange reactions can be expressed as follows;FeTiO₃+MnCl_2aq=MnTiO₃+FeCl_2aqMnTiO₃+MgCl_2aq=MgTiO₃+MnCl_2aqand MgTiO₃+FeCl_2aq=FeTiO₃+MgCl_2aq. Under the experimental conditions, FeTiO₃, MnTiO₃ and MgTiO₃ make a perfectly continuous solid solution. Based on thermodynamic analysis using ternary solid solution model of Kakuda et al. (1991), interaction parameters (W_i) for the ternary ilmenite solid solution have been obtained to be W_FeFeMn=-0.02, W_FeMnMn=-0.19, W_MnMnMg=2.99, W_MnMgMg=3.34, W_MgMgFe=1.23, W_MgFeFe=1.03 and W_FeMnMg=1.83kcal/mol. FeTiO₃-MnTiO₃ solid solution is regarded as ideal solution, and MnTiO₃-MgTiO₃ and MgTiO₃-FeTiO₃ solid solutions show positive deviations from ideal solution. Ferrous ion is preferably partitioned into ilmenite solid solution. On the other hand, manganese ion tends to concentrate into aqueous chloride solution.

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Computer simulations based on the interatomic interactions have been used extensively to interpret and predict the structural and physical properties of minerals. In this review we describe the application of (1) the static lattice simulation to the structure and elastic constants of MgSiO₃ perovskite, (2) the molecular dynamics method to the structural and physical properties, and a possible phase transformation of MgSiO₃ perovskite under high temperatures and pressures, and (3) the lattice dynamics method with the quasi-harmonic approximation to the vibrational and thermodynamic properties of forsterite. The strengths and limitations of such computer simulations are presented. We show the computer simulations, when used with accurate interatomic potentials, as effective and powerful tools for atomistic studies of both static and dynamic properties of minerals.

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The application of mineralogy to making refractories was outlined. Prior to this century, the relation of mineralogy to refractory industries had been confined to the range of discovering and developing nonmetallic ore deposits for raw materials of refractories. With the advent of modern measuring apparatuses employing X-rays early in this century, mineralogy and refractory researches have shared the same studying means and become connected each other more intimately. On the other hand, a basic difference remains between the two: Mineralogy never strives to produce materials of definite shape or dimensions while refractories are always required to maintain both of the expected physical properties and the specified dimensions. Insofar as the phase diagrams are concerned, fused cast refractories maintain a closer relation to mineralogy than any other type of refractories such as burned bricks, etc. The recommended range of chemical composition of fused cast refractories called AZS is also discussed, construing the crystallization course in the phase diagram, as an example.

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The ionic conduction is one of the interesting physical properties which have been studied for minerals. In this paper, we present a basic classification of solid electrolytes based on the conduction mechanisms. An overview of the complex impedance method, the Tubandt method and isotope tracer method are also presented in relation to the ionic conductivity measurements of the solid electrolyte minerals such as proustite Ag₃AsS₃, cerargyrite AgCI and iodilite AgI. The studies on the structure and dynamics of ions in superionic conducting phase are reviewed mainly by diffraction method. We describe the behaviours of solid electrolytes such as the activation energies for conduction, the transport number of mobile species, enhanced ionic conduction in multiphase systems and the thermal behaviour and diffusion path of the mobile ions.

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Specially designed equipments have been developed to realize 1.7 - 21 keV SR-EXAFS measurement apparatus for thin film structure studies. Not only usual measurements, but also reflectivity and fluorescence measurements under total reflection conditions are utilized to obtain EXAFS and to characterize the structures and surfaces of thin films. The analyses of the EXAFS reveal the structure differences among the amorphous thin films which were formed or thermally treated in the different conditions. These results are very important to develop the semiconductor and various electronic devices.

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