Attempt to grow anorthite by the flux method has been made for several years, which showed the good prospect for the flux system of CaO-V₂O₅ with Li₂O and/or B₂O₃ and led to the crystal of ca. 10x5x2 mm. Although the transparent single crystals of 1-2 millimeters were obtained, the crystals larger than several millimeters were mostly translucent or colored in pale yellow, and were often cracked or polycrystalline. The coloration was related to the flux composition, and the better results were obtained in the system CaO-V₂O₅-Li₂O. The crack was presumed to be formed on cooling after the growth, so we tried to improve the cooling. At present, however, a remarkable improvement has not been achieved.

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Cancrinite [Na₆OCa₂(AlSiO₄)₆(CO₃)2•2H₂O] is one of feldspathoid minerals that have three-dimensional framework structure. Recently, a new cancrinite-group mineral named kyanoxalite, which has oxalate anion in the extraframework site, was reported from the alkaline pluton at Kola Peninsula, Russia (Chukanov et al., 2010). The formation mechanism of kyanoxalite was not elucidated, hence, in this study, we attempted to synthesize oxalate-bearing cancrinite under the condition mimiking the occurence of kyanoxalite in nature. Natural kyanoxalite co-exists with sodalite-nosean minerals and thus hydrothermal treatment of sodalite with sodium oxalate solution (0.3M, 200 °C) was carried out for 5 days. The products of the hydrothermal experiment were analyzed with powder-XRD, ATR-FTIR and TG-DTA. Powder XRD pattern of the product revealed that sodalite transforms into cancrinite (Fig. 1), FTIR and TG-DTA suggest that oxalate anion is occluded in the extraframework sites in the resulting cancrinite. This study suggests that kyanoxalite formed by the hydrothermal alternation with oxalate-bearing fluids.

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High-pressure single-crystal X-ray diffraction study on d-AlOOH were performed with synchrotron radiation up to around 9 GPa to observe the pressure induced structural transition of this phase. X-ray diffraction intensity data showed that the space group of d-AlOOH was changed from P21nm to Pnnm at around 7 GPa.

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The shoulder peak associated with the main peak at 3700 cm-1 of brucite, Mg(OH)2 has not been characterized in the previous studies. In this study detail analyses on FT-IR spectra of brucite was conducted to examine the causes of the shoulder peak, which is associated with the peak of OH-stretching vibration located at 3700cm-1. As result from the chemical analysis with EPMA (EDS type), Mn and Fe atoms were included in this brucite sample. The results from chemical analysis showed that (Mn+Fe) / (Mg+Mn+Fe) ratio was 0.06-0.08 %. FT-IR spectra of brucite showed that the 3691cm-1 peak was observed as a shoulder peak in the peak of OH-stretching vibration located at 3700cm-1.

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Spinel structure has two important sites; tetrahedral T-site and octahedral M-site. In the spinel series minerals, there is a relationship between the equilibration temperature and T-O and M-O lengths. The purpose of this study is tried to estimate the equilibration temperature of a natural spinel from Madagascar using T-O and M-O lengths. The chemical formula of this sample was determined as Mg0.94Fe0.04Al2.00O4 by EPMA analysis. Main crystallographic information were obtained by single crystal X-ray diffraction measurement as follows: the lattice constant (a) was 8.0915(6) Å, the oxygen fractional coordinates (u) was 0.26363(4). And the equilibration temperatures calculated from T-O and M-O lengths, which were corrected for the effect of iron, were 561 K and 585 K, respectively.

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Magnetite exhibiting strong magnetism is called "loadstone". Previous studies showed that the magnetic properties of magnetite are attributable to the micro-structures developed during oxidation. The purpose of this study is to clarify a relationship between magnetic properties and mineralogical characteristics of 10 magnetite samples from 9 localities. Magnetic hysteresis loops were obtained by MPMS. Chemical compositions were obtained by EPMA. The lattice constants were calculated from the reflections observed by XRD. Reflecting microscopy revealed the micro-structures of the samples. Zonal structures were observed in some samples. A correlation is recognized between the saturation remanence and the Si content of magnetite.

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We studied to clarify the movement frequency and the movement style of Mg and O vacancies in periclase (MgO) using molecular dynamics simulation. We calculated in the size of cells between 6x6x6 and 10x10x10, at atomosphere and the temperature from 300K to 3000K. The MD cells contained a vacancy of Mg and O one by one. Vacancies moved above 1600K, though their didn't below 1600K temperature. The movement frequency of Mg vacancy was higher than O. Each of the movement frequency of Mg vacancy and O has increased in exponential as the temperature increases. Coupled vacancies at the lower temperature have longer duration time than at the higher temperature.

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Structural change of synthetic opal (SiO2nH2O) by heat treatment up to 1300 deg C, has been investigated by using SEM, X-ray diffraction method (XRD), Infrared (IR) and Raman spectroscopies. Synthetic opal is considered to consist mainly of the four-membered ring of SiO4 with containing large quantity of water molecules and internal and surfaces silanole groups in the structure. Up to 600 deg C, a great number of silanole is dehydrated and polymerized to form the new Si-O-Si linkage. Average structure of this network is four-membered ring. However, the network of SiO4 undergoes thermal reconstruction above this temperature. Four-membered ring in synthetic opal may be relaxed to larger ring such as six-membered ring. Therefore, six-membered ring becomes dominant with increasing heat temperature. By heating at 1000 deg C, the structure of opal approaches to that of silica glass, whose average structure is six-membered ring. Above 1200 deg C, the structure of opal changes to that of cristobalite.

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CL spectral analysis of annealed zircon samples up to 1200 degree C reveals that the band emission related to radiation-induced defect center in metamict state decreases in an increase of annealed temperature and disappeared above 700 degree C. The CL emission of intrinsic defect center in blue region gradually increases in heating due to a recovery of its crystal field. CL analysis can provide useful information on characteristic of the features of metamict zircon rather than other methods.

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CL spectral analysis of dolomite samples reveals that divalent Mn ions act as an activator for red CL emissions which can be divided into two components related to Ca and Mg sites occupied by Mn ions. Low temperature CL measurements lead to precise determination of coefficient of Mn partition between two sites in dolomite. Preference incorporation of Mn ions into Mg site is recognized for almost samples, suggesting a control of ionic size for such substitution.

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CL spectral analysis of smithsonite samples reveals two broad emissions in blue and red regions. The former is assigned to defect centers composed of two or more components, and the latter to an impurity center of divalent Mn ion occupied in Zn site. An increase in sample temperature reduces an intensity of CL emission in blue region, suggesting a typical temperature quenching, whereas the intensity of red emission makes no significant change in a wide temperature range.

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Cathodoluminescenec (CL) imaging and spectroscopy have been used to clarify growth fabric textures observed in authigenic and biogenic minerals during diagenetic process. A cathodomicrofacies analysis has been developed in the field of environmental geology and archaeology, especially for the study with biogenic carbonates. Few investigations of silicified fossils have been done so far. In this study a microfacies analysis of petrified wood has been carried out by CL imaging and spectroscopy combined with Raman spectroscopy.

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Syntheses of emerald were performed by flux-method using Pt-crucible and electric furnace. The principal ingredients are BeO, Al2O3 and SiO2. The coloring reagent is Cr2O3 for green color. The fuxes are MoO3 and Li2O. As obtaining several kinds of crystals, crystal forms, surface structures and crystal data are reported.

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A lot of studies have been carried out on cordierite by many geologists and mineralogists. One of the important characteristics of Cordierite is its low thermal expansivity and an anisotropy of thermal expansion coefficient. This characteristic thermal properties have been attracted not only mineralogists but ceramic scientists' attention. Kurosaki Harima Corporation designed a new ceramics, "NEXCERA" as materials of apparatus for high precision analysis. This new ceramics achieved almost zero thermal expansivity and excellent mechanical characteristics. An observation, chemical analysis and crystal structure analysis with TEM and XRD carried out to examine the basic properties of cordierite composed of the ceramics. Based on these results, the effect of dopant elements and thermal history will be discussed.

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Serpentine minerals has three polymorphs;lizardite,antigorite and chrysotile.Yada(1971) showed two types of chrysotile tube structure;spiral and concentric.Veblen and Buseck(1979) found varieties of serpentine structures by HRTEM. However, detailed formation and growth process of varieties of serpentine minerals structures are not known yet. We observed some chrysotile structures formed from pyriobles in Oeyama metamorphic rocks by TEM and discussed about their growth process from pyriboles.

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Both theoretical and practical study on the combination of bullets of snow was conducted. The universal and theoretical study revealed that under some specific conditions which realize the Ostwald's step rule, the metastable phase crystals are born first, and then the stable phase crystals nucleate on them. On the basis of the theoretical study, the experiments for artificial combination of bullets of snow were conducted. In the cold room at Nishiborieizaburo kinen Explorer Museum in Higashiomi, Shiga Prefecture, micro water droplets were introduced into the cooled vessel to be frozen and grew. After that, they were recovered for microscopic observation. As a result, combination of bullets in nature was recreated for the first time in the world.

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The volcanic rocks of the Western and the Eastern Mirdita Ophiolite (Albania) are geochemically characterized by mid-ocean ridge basalt(MORB)-like and arc-like signatures, respectively(Smith, 1993). Major element compositions of minerals in Gomsiqe lherzolite indicate low-degree of partial melting and are similar to those of ocean floor peridotites. Dunites in the Gomsiqe massif are classified into low(0.3) and high(0.7)-Cr#[=Cr/(Cr+Al) atmic ratio] spinel-bearing dunite. The former might be formed by the reaction with MORB, whereas the latter might be formed by the reaction with arc-related magmas. The Gomsiqe massif might experience a sequence of events in response to the change in tectonic setting from oceanic lithosphere formed at the mid-ocean ridge setting to the island arc setting.

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Seifertite and stishovite in a shocked lunar meteorite were investigated by a FIB-TEM technique. Major original silica phase in the lunar meteorite is cristobalite with a twin texture. A cristobalite grain with a tweed texture contains rhomboid or spindle-shaped seifertite crystals. Many stishovite platelets are formed in a cristobalite with a lamellar texture. There is a specific crystallographic relationship between cristobalite and stishovite. Seifertite and stishovite would be formed by incoherently and coherent mechanism, respectively. Considering thermal gradient in the silica grains, a clapeyron slope between stishovite and seifertite is negative.

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Phase relations in the system TiO2-ZrO2 were examined at 4-12 GPa and 1800 C, using a multianvil apparatus. It was found that alpha-PbO2 type solid solution is stable between 100 and 60 mol% TiO2 in the system. This indicates formation of solid solution between mineral srilankite (ZrTi2O6) and alpha-PbO2 type TiO2 at high pressure and high temperature.

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The high-pressure study of electrical conductivity of carbonates has been performed by the multi-anvil press experiments. In the case of magnesite, the electrical conductivity increased with increasing pressure. The negative activation volume and relatively large activation energy of magnesite implies that the hopping of large polarons in the dominant mechanism at high pressure and temperature. In the case of natural dolomite, the electrical conductivity was higher than that of magnesite.

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The compression data of both (Mg0.83,Fe0.17)O and (Mg0.75,Fe0.25)O ferropericlases have been measured up to 60 GPa at the three temperatures of 300, 700, and 1100 K, using synchrotron powder X-ray diffraction experiments with a Kawai-type multi-anvil apparatus and sintered diamond anvils. Temperature-pressure-volume equations of state of both ferropericlases with high spin Fe2+ ions have been developed using these measured compression data below ∼50 GPa, based on the Mie-Grüneisen-Debye type model, with the 300 K Birch-Murnaghan equation. We have found that the calculated pressures based on these EOS models reproduce the measured pressures of the two ferropericlase below ∼50 GPa very accurately over the three temperatures of 300, 700, and 1100 K. We have further found that for each ferropericlase, and for each temperature of 300, 700, and 1100 K, a clear volume reduction from the compression curve with high spin Fe2+ starts at ∼50 GPa and the volume reduction increases with increasing pressure, due to a progressive high spin to low spin transition in the Fe2+ ions.

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Calcium ferrite-type MgAl2O4 is one of major endmembers of a calcium ferrite phase. In this study, mode Grüneisen parameters of calcium ferrite-type MgAl2O4 were determined from pressure dependences of lattice vibrational frequencies by high-pressure micro-Raman spectroscopy using a diamond anvil cell apparatus. By combining them with the results of a vibrational mode calculation, the thermal Grüneisen parameter was obtained to be 1.50(5) from a weighted average of the mode Grüneisen parameters for all optic modes.

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Presence of untransformed metastable minerals may contribute to slab stagnation because it produces a buoyancy force. Here we report experimental results on the Si-Al interdiffusion rate in majoritic garnet, which controls the kinetics of the pyroxene-garnet transformation. The result indicates that large low-density metastable regions exist in the slab.

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Water contents of Al-bearing minerals in the mantle transition zone and the lower mantle were determined in the systems pyrope - enstatite with H2O of 11.3 wt% and 18.7 wt% at pressures of 20-26 GPa and temperatures of 1473-1873K. The water contents of Al-bearing experimental products were measured by secondary ion mass spectrometry (SIMS) in Hokkaido University, and found the water contents as follows : perovskite ∼0.8 wt%, garnet ∼0.6 wt%, stishovite ∼1.4 wt%, phase D ∼22 wt%. These water contents were strongly related to the Al contents of these phases. Thus the water contents in the Earth' s mantle minerals are strongly related to the Al contents.

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Spin transition of iron in the lower mantle and its effects on iron-partitioning among the iron-bearing phases and phase transition pressure from Mg-perovskite to post-Mg-perovskite are discussed.

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We have measured the sound velocity of hcp-Fe and Fe3S using the inelastic X-ray scattering study at high pressure. Based on the measurements and the phase relation of the Fe-Fe3S system, we presented a model of the inner core formation; the eastern-hemisphere of the inner core with a weak anisotropy and slightly lower sound velocity was formed by hcp-Fe crystallizing earlier, whereas the western hemisphere of the inner core with anisotropy and higher sound velocity might be composed of the two phase mixtures containing Fe and Fe3S crystallizing in the later stage.

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An in situ synchrotron powder X ray diffraction study on (Fe0.89,Ni0.11)3S was conducted up to 141 GPa and 1590 K. (Fe0.89,Ni0.11)3S has a tetragonal structure, which is the same structure as Ni-free Fe3S. Fitting a third-order Birch-Murnaghan equation of state to data at ambient temperature yielded a bulk modulus of K0 = 138.1(7.2) GPa and its pressure derivative K0' = 4.5(3) with a zero pressure volume V0 = 375.67(4) Å3.

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We present experimental data in the Fe-C system and results on the equilibrium carbon isotope fractionation between graphite/diamond and iron carbide melt at 5 GPa and 10 GPa at a temperature range of 1200 to 2100C. Our results suggest that iron carbide melt will preferentially gather 12C than 13C, which is temperature dependent and are consistent with the carbon isotope distribution observed between graphite and cohenite (Fe3C) in iron meteorites. The temperature dependent fractionation between iron carbide melt and graphite/diamond finds potential application in determining the temperature of formation of meteorites and metallic core of planetary materials. Furthermore, we anticipate that the temperature dependent fractionation of carbon isotopes between iron carbide melt and graphite/diamond is an effective mechanism that created a "12C enriched core".

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The phase relations of FeTiO3 were investigated up to a pressure of about 77 GPa and a temperature of 2600 K by synchrotron X-ray diffraction using a laser-heated diamond anvil cell and analytical transmission electron microscopy observations of recovered samples.

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We performed experiments under high-temperature and high-pressure to investigate effects of Fe and Al on water partitioning between olivine and orthopyroxene. The water contents of recovered samples obtained from in vacuum Fourier transform infrared spectroscopy and Paterson's equation. This study shows the effect of Al on water partitioning between olivine and orthopyroxene is significant lager than Fe.

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Experimental studies of Ni-Co ion exchange reaction between biotite and K,Ni,Co bearing hydrothermal solutions were performed at 600C, 100MPa.Ni have a tendency to fix preferentially in biotite.

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We have developed density measurement technique using X-ray micro-CT at high pressures. Our method is based on the X-ray absorption. High pressure X-ray micro-CT yields the sample length as well as the sample absorption. Then we can evaluate the sample density from Lambert-Beer law. Here we report the results of the reconnaissance experiments using the polycrystalline KBr up to 1.2 GPa. Densities of KBr determined by X-ray tomography are consistent with the X-ray diffraction densities.

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Water changes the properties of magma such as viscosity, density, and sound velocity, when it is dissolved into magma. Therefore, structure of hydrous silicate melts have been studied intensively, especially with respect to the water species in silicate melts. We have studied the hydrous silica glass, which was quenched from 200 MPa and 1500 C, by the X-ray diffraction analysis using synchrotron radiation.

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Colloidal particles in deep subsurface play an important role in transportation of various materials. However, their characteristics are not revealed enough according to difficulties of sampling and analysis. In this study, colloidal materials were collected from a borehole in the Toki Granite at the depths of 650 and 1150 m using ultrafiltration (10 kDa) under anaerobic condition. TEM observation of a filter was conducted after preparation of ultrathin sections by FIB. Colloidal materials were composed of amorphous iron oxides and hematite nanoparticles. Very fine particles of the iron oxides (<50nm) implies rapid formation of the iron oxides by oxidation during borehole drilling. Coexistence of amorphous silica with the iron oxides may increase stability of the iron oxides in groundwater because of inhibition of crystal growth. This study was supported by grants from the Nuclear and Industrial Safety Agency (NISA).

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Cs contamination of soils in relation to Fukushima Nuclear Power Plant accident was examined from standpoint of environmental Mineralogy.

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Life is ubiquitous not only in the near-surface environment, but also in the deep-sea and crustal environments below 120 degrees Celsius, which is known as an upper limit for life. Chemical reactions mediated in the earth's biosphere result in the formation of nanometer-sized solid phases, which are often metastable and controlling global geochemical cycles. Over the past decades, technology has been developed to directly observe nanoparticles and to clarify the possible mechanisms of nanoparticle formation. Theories that describe the formation of nanoparticles will be presented to discuss problems encountered by studying complex biogeochemical systems and to suggest the possible solutions for these problems.

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Two REE patterns (type C or Y) obtained from the lunar samples are applied to terrestrial rocks and minerals. Many terrestrial rocks shows two types C and Y with complicated formation processes, but some rocks and minerals reveal one type C or Y. The Sudbury impact breccias from Ontario, Canada show the REE type C, but contain significant grains of carbon and chlorine, which indicates origin and evolution at shallow ocean impact.The present method can be applied to other unsolved crater and structure.

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Darhad basin in northern Mongolia is located in the continent where is sensitive to the climate change. Hydrologic events with climate changes occurred in this area. For example, according to data from previous study, it is suggest that Darhad basin formed ice dam lake by Pleistocene glaciers and the lake repeated drainage and impounded water. Disturbance of equilibriaa between minerals and solution in Lake caused by climatic changes leads to the water-mineral reaction. In consequence, The records of biological and chemical reaction resulted from such reactions are preserved in the mineral compositions in lake sediments. Therefore, it is expected that lake sediments from Darhad basin would have record of evolution of water chemistry over the past a few million years. We tried to reconstruct evolution of water chemistry of the paleolake by mineralogy analysis of lacustrine sediment from Darhad basin.

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A quantitative pattern of atmospheric oxygen evolution must be estimated to understand the Earth surface of the Paleoproterozoic. Although it is proposed that atmospheric oxygen increased from 10^-6 to 10^-3 atm between 2.5 and 2.0 Ga, the variation of atmospheric oxygen during glacial and interglacial periods are not known. It is concluded that a weathering model developed by our group can estimate the oxygen levels in the interglacial periods but not those in the glacial periods.

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Although there have been numerous studies about the rise of atmospheric oxygen level during the Paleoproterozoic, the quantitive pattern of the oxygen rise is still not fully understood. Recently, Murakami et al. (2011) showed Fe(III)/Fe(II) rations recorded in paleosols can give quantitive information about oxygen levels at the time of their formation when kinetically analyzed. As the same kinetical approach, Yokota et al.(2008; in prep.) constructed the weathering model which predicts Fe(III)/Fe(II) ratios as a function of atmospheric oxygen level, revealing the ratio of Fe(III)/Fe(II) is mainly determined by Fe(II) oxidation rate and sweep-out rate of Fe(II) by groundwater flow. Taking Parameters for Fe(II) oxidation rate from recent reports and estimating those for sweep-out rate of Fe(II) by groundwater by focusing Si behavior in paleosols, the model was improved.

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To evaluate the interaction between chemical weathering and physical weathering, a laboratory experiment was conducted using Berea sandstone (porosity: 22%, grain size: 0.2 mm, mineral composition: quartz 90%, fine quartz grains and carbonates are present as matrix between sand grains). The sandstone sample was soaked in deionized water and reacted while the reactor was shaken to simulate the effects of wave and water flow. Overall weathering proceeds by the dissolution of elements from minerals (chemical weathering) and detachment of grains (physical weathering). After two months of reaction at 25°C, total amount of ions dissolved was 0.3 mg cm^-2 and that of grains detached was 0.1 mg cm^-2. Most of the grains detached were fine quartz and little sand grain was detached. From these results, it is inferred that the cementation at the matrix portion is weakened by dissolution in initial stage of weathering, and overall weathering proceeds by the repetitions of the detachment of grains and the weakening of cementation.

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The dissolution behavior of the barite (001) surface in pure water at 30C was investigated using in situ AFM, to better understand the dissolution mechanism and the microtopographical changes that occur during the dissolution. The dissolution of the barite (001) surface could be divided into three stages. The first stage of the dissolution was characterized only by the retreat of various steps that were formed mechanically by the initial cleaving. During the second stage, the change in the retreat behavior (from a <hk0> step with one layer to a f step with an upper half-unit cell layer and a s step with a lower half-unit cell layer) and the formation of etch pits were observed. The last stage of the dissolution was characterized by an increase of the stable steps parallel to the [010] direction, followed by a decrease of steps parallel to <hk0> and the development of angular deep etch pits.

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There is an argument for the calcium carbonate phase constituting larval shells of mollusks, especially the existence of amorphous calcium carbonate (ACC), is under discussion. In this study, we have investigated the larval shell of Pinctada fucata, using various analytical techniques to solve this problem. From TEM observation of the specimen made by FIB, the larval shell consists of three layers all of which are made of aragonite and ACC was not found. However, this result may be an artifact due to heating during FIB preparation. Hence, we analyzed the shell using XRD, and FT-IR, and Raman spectrometry. XRD and Raman spectrometry showed no sign for the existence of ACC. Only FT-IR spectra contained the peak, assignable to ACC.

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Monohydrocalcite (CaCO₃ H₂O: MHC) was found from sediment core at lake Hovsgol, Mongolia. It is estimated that MHC was formed during the cold periods. It may be possible to estimate water quality condition of lake Hovsgol during the cold periods by understanding the formation condition of MHC. Synthesis experiments of carbonate minerals from various concentration of Ca, Mg CO₃ were conducted to find the formation condition of MHC.

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In present study, we tried to reproduce the mineralogical and petrographical evolution of bentonite with iron-rich hydrothermal solution observed in Kawasaki bentonite deposit by means of the one-dimensional reactive transport modeling by PHREEQC. The geochemical modeling can generally reproduce the mineralogical evolutions of the bentonite observed in Kawasaki bentonite deposit. The results of modeling also revealed the several important aspects in regard with the iron-bentonite interactions. For example, the vein was formed by the reaction between the hydrothermal solution and bentonite. Although the pore water chemistry in the bentonite was strongly affected by the interaction with the hydrothermal solution, the mineralogical compositions of bentonite are little affected by the reaction after several 100 years.

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Arsenic contamination of groundwater in Vietnam found recently, the water chemistry characteristic high Manganese levels. Drilling sediments of 74 m in depth in Tay island in Dong Thap province were obtained and examined. The constituent minerals of the sediments are mainly quartz, micas, feldspars, kaolin minerals, illite, smectite, and vermiculite. Arsenic concentration and correlation pattern with Fe, Mn, Al, P and LOI were different in sediments of Holocene and Pleistocene. They may be due maily to different sedimentary environment. Moreover, we found three types of groundwater chemistry: 1) high As and Fe contents with low ORP, 2) high Mn contents with relativity high ORP, and 3) extremely high Mn and Fe type water. The characteristic water chemistry is very similar to that of Cambodia (Buschmann et al., 2007). A characteristic model for Arsenic contamination along Mekong River was proposed and discussed.

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TEM obserevation was carried out on bacteriform on natural gold from Sado, Niigata Japan. The specimen was prepared by using FIB.ED pattern showed characteristic features.

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Recently we have found weak extra reflections similar to c-reflections in the ED patterns of calcite precipitated in a hot-spring (La Duke) near Yellow Stone National Park. However, X-ray microanalysis indicated that the amount of impurity cations such as Mg²⁺ is very small and sulfur is the major impurity element. S/Ca atomic ratio is about 3%. The cell parameters of the La Duke sample determined from XRD, indicated that the a-length (4.9803Å) is slightly decreased and the c-length (17.076Å) slightly increased compared to the pure calcite (a = 4.9857Å, c = 17.0624Å). The Selected-area ED pattern along the [001] direction indicated that the extra reflections appear holding the three-fold symmetry of calcite. Combining these results and with a future experiment to determine the chemical species of sulfur by XPS, we are now constructing a model of the superstructure to form c-reflections in the present specimen.

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Coccoliths are calcified scales formed around unicellular alga, Coccolithophore. They are divided into three types according to their morphology: heterococcolith, holococcolith, nanolith. Recent SEM-EBSD study indicated the variation of Cretaceous heterococcolith crystallographic properties. In this presentation, we report the crystallographic properties of Cenozoic fossil heterococcoliths and nanoliths using SEM-EBSD and SEM sterophotogrametry.

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It is general known that reef coral skeletons are consisted of aragonite (CaCO₃) based on the result of XRD. The other hand, chemical analyses reveal that coral skeletons include variety elements. One of these elements Sr is displace Ca in aragonite. The other elements in coral skeleton like Mg, Al, Na, S and so on, do not replace Ca. Some of them are considered to related the organic matrix, but only S is confirmed the related organic matrix. Although the fluctuation of Mg/Ca and Na/Ca ratio reflect the surrounding changes during the coral skeletons growth, it is poorly know how these elements are captured into coral skeleton. We exam the possibility these elements may take into as mineral except aragonite through the observations from nano to micron meter order.

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