Recent developments in crystal chemistry of minerals are reviewed and several problems are suggested to be investigated as extensions of the presented accomplishments. Electron-density distributions in inorganic crystals have been extensively investigated for these twenty years, and valuable information has been obtained on electronic states of crystals with simple structures. It is supposed to be most promising for more complex crystals to collect diffraction data with extremely small single-crystals by making use of intense X-rays of SR. Single-crystal X-ray diffraction data afford not only electron-density distributions, but also anharmonic thermal parameters for atoms in the crystals. The knowledge on anharmonic thermal vibrations obtained at various temperatures and pressures might be useful to check the varidity of the interatomic potentials assumed in molecular dynamics calculations for simulating the states of materials in the Earth's interior. Consideration of anharmonic thermal vibrations is also important to get correct positional parameters of atoms. In the case of LiTaO₃, the z parameter of Ta shifted by 0.066 A relative to Li and O on introduction of anharmonic thermal parameters into the parameters to be refined in the least-squares calculations. The author and his collaborators succeeded to grow a low temperature form crystal of BaB₂O₄ at a temperature above the phase-transition point from a supercooled melt of pure BaB₂O₄. A similar crystal growth of a low temperature form is expected for rock-forming silicate minerals, since silicate melts are easily supercooled.

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Mineralogy in Japan during the last decade after the 30th Anniversary of the Mineralogical Society of Japan has been reviewed. Two large reforms are necessary to make Mineralogy in Japan an attractive field, i.e. (1) the large reform of the scientific lecture meeting and (2) the large reform of the university concerning to the lectureship, the personal administration, the lectures etc.

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We describe the molecular dynamics (MD) method to simulate the structural and physical properties of minerals at any temperature and pressure. The MgSiO₃ polymorphs are used to illustrate the reliability and applicability of this atomistic simulation technique. The MD simulation is further attempted to predict possible phase transitions which might occur at elevated temperatures and pressures.

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Interatomic bond is of quantum mechanical origin and has many-atom characters. Thereby it is generally difficult to express the interatomic potential empirically in terms of simple analytic functions. Applicability of such a simple form is certainly limited and a success in one case does not necessarily guarantee success in other cases. Recent progress in the first-principles electronic structure calculation enables us to evaluate the forces acting on atoms in any circumstance equally well. In this connection, a brief review of the CarParrinello method will be given and an example of its application to silica will be presented.

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Recent developments of methods and applications of computer simulation for crystal fractionation and cooling histories of minerals are given after reviewing computer simulation of crystal structures of mantle minerals. Simulations of the structures have been applied to diffusion phenoma of ions in minerals and to possible derivation of partition coefficients of trace elements during crystal fractionation. Cooling rates subsequent to crystallization of meteoritic minerals have been estimated by simulation of diffusion profiles in minerals by a computer.

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Numerous works based on molecular orbital method have been done on minerals in this one decade. These are categorized into main four fields ;(1) molecular mimicry of bond length and angle variations(2) construction of pairwise potential from calculated potential surface(3) mapping of electron density distribution(4) determination of atomic charges in minerals.In this paper these applications of molecular orbital method are reviewed with some examples. Finally, a recent development of new method, periodic Hartree-Fock method, is introduced with examples, which might become a powerful tool for mineralogy.

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Recent developments on quantum chemical methods of molecules allow us to know detailed informations of chemical bonds in inorganic materials. There are, however, some diffculties arisen from the finite cluster treatments. Using the quantitative knowledges of chemical bonds, we can calculate and predict structures and physical properties by means of molecular simulation methods. The semiempirical and empirical treatments of the interactions between atoms are discussed for the use in the molecular simulations.

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Recent developments in experimental mineralogy are reviewed. Significant advancement has been made as follows: (1) recent development of the high pressure technology, such as the diamond anvil cell and the multi anvil apparatus, made it possible to characterize the stability fields, crystallographic and physical properties of the mantle minerals synthesized at high pressure by using these high pressure apparatuses; (2) various techiniques have been developed to make “in situ” observation of the physical properties and kinetics of the phase transitions at high pressures and temperatures; the techniques for the “in situ” observation are the high pressure and temperature X-ray diffraction using synchrotron radiation X-ray source, the high temperature transmission electron microscopy, in situ optical microscopic observation in the aqueous solutions and the high temperature silicate magmas, spectroscopies at high pressure by using the diamond anvil cell.

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On the occation of the 10th anniversary of the Photon Factory, National Laboratory for High Energy Physics, Tsukuba, Japan, a review of work done in the field of mineralogy has been made. This paper includes a complete list of the publications in the field of the mineralogical applications of synchrotron radiation in Japan, covering the development of instrumentations and mineralogical applications of X-ray diffraction, XAFS, X-ray fluorescence analysis, X-ray topography and computerized tomography.

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1.7-21 keV SR-EXAF Smeasurement system was constructed for thin film structure studies.Reflectivity and fluorescence measurements under total reflection condition are utilized to obtain EXAFS and to characterize the structures of thin films. The analyses of the EXAFS reveal the structure differences among the amorphous thin films which were formed in the different conditions. These analyses are important to develop various electronic devices.

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This paper reviews the important technical improvements accomplished during these ten years mainly in the field of the use of the diamond anvil cell at high temperature and pressure X-ray measurements. A brief historical introduction to devices are presented in Sec. 1. The improvements in the design of the diamond anvil are reviewed in Sec. 2. The improvements of heating technique, especially laser heating are reviewed in Sec. 3. Various high temperature diamond anvil high pressure cells are reviewed in Sec. 4.

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Microgravity has been utilized not only for verifying the theories on diffusion of molecules in the liquid but for understanding the phenomena which are damped by gravity on earth and thus are invisible or not measurable, such asdiffusion controlled growth, surface tension dirven convection (Marangoni convection) or pure homogeneous nucleation. These phenomena have a lot of influences on the growth of crystals. Some microgravity experiments were already started by the present author.

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Studying the shallow part of the Earth's crust significantly contributes to human life. In the shallow crust, minerals react with the help of water and material moves by dissolution in water. Thus, experimental studies on the interaction between minerals and water at low temperatures (below 500 K) are important. However, these experiments have some problems. First, it is difficult to analyze the minerals synthesized at low temperatures, because they are fine-grained clay minerals or amorphous materials. However, recently developed analytical methods, such as NMR. EXAFS and Raman spectroscopy, may be used to analyze these materials. Second, because of the slow reaction rate at low temperatures, most synthesized materials are meta stable, and it is difficult to explain their stability thermodynamically. To explain the stability of the meta stable phase of silicate minerals, it is necessary to also consider the structure of synthesized minerals.

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Carbon exhibits a wide variety of behaviors that depend on the surrounding environment and processing techniques, reflecting different kinds of chemical bond nature. Carbon forms have been calssified by the type of sp hybridization, sp¹, sp² and sp³. Recently, several metastable forms were synthesized experimentally and also a few hypothetical forms were proposed on the base of theoretical calculation. These carbon forms represent some modified sp² and/or sp³ bonds. This suggests that hybridization of carbon atom is allowed to extend from those defined by an discrete integer and geometric symmetry to those by fraction and asymmetry.

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Understanding of the physical and chemical properties of oxides in termes of the molecular structure is a fundamental problem for geology, ceramic science and steel making process. In this paper, examples of applications of high temperature NMR to oxides up to 1200°C are descrived to show problems and present level of understanding. ²⁷Al NMR studies of MgAl₂O₄ spinel, ¹¹B NMR relaxation studies of Na₂O-B₂O₃ melts and ²⁹Si NMR studies of Na₂O·3SiO₂ melts are discussed as examples.

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Solid (liquid)-gas equilibria and their phase changes (vaporization, condensation and solid-gas reaction) are important phenomena for understanding processes in the primary solar nebula. Experimental studies of such phenomena have been reviewed in relation to the planetary sciences. Such experiments, called as experiments for condensed phase-gas systems, have several characteristics due to nature of a vapor phase; (1) the entropy of a vapor phase is much larger than that of a condensed phase and (2) the volume of a vapor phase is much larger than that of a condensed phase. The former is responsible for easy thermochemical calculations of solid-gas equilibria and importance of phase change kinetics including a vapor phase, and the later is responsible for not doing experiments in closed systems. Previous work and feature problems on experiments of solid (liquid)-gas equilibriua, vaporization, condensation, and solid-gas reaction have been discussed.

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'A mineral' is defined as an anisotropic solid state substance whose origin and properties are left to be elucidated. 'Mineralogical Society' which consists of the people interested in minerals should work the survival of mineralogy. Every member should appeal the activities of the mineralogists including his to the scientists of the related fields. It is proposed that the present three mineralogical societies in Japan be unified.

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The new trends of mineralogical sciences have been suggested with a special emphais on the development of in-situ characterization techniques such as microspectroscopy, the quantitative color description by colorimetry and the quantitative representation of forms and textures of the real rock and material systems. The systematic treatments of heterogeneous mineralogical kinetics including solid-liquid and solid-gas reactions, diffusion, phase transformation and rheology should also be advanced. The background of these new mineralogy depends on their academic environments and the education of younger generation. Young Mineralogist Organization (YMO) has been working since 5 years to provide a forum of communication and crossover of mineralogical people who are mentally young. In order to take over these interdisciplinary interactions into the academic societies themselves, the unity of 3 mineralogy related societies and their English journals should be envisaged.

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Education of mineralogy were discussed. Consequently some proposals are made for improving education of mineralogy.(1)publication of textbook of mineralogy, (2)proposals to the school curriculum positively, (3)maintain good condition of education and researching in advanced education, (4)correspondence to social needs with mineralogical society, (5)preparation of mineralogical environments in actual society-example for establishment of museum.

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