Seven comet Wild 2 samples returned by the Stardust mission were studied using transmission electron microscopy. Our study shows that three samples consist mainly of olivine and pyroxene and four samples consist of Mg-Fe-bearing Si-O glass with minor amounts of Fe-Ni sulfide and metal. The olivine in the silicate-rich samples differs in fayalite content between the samples and shows a wide range of fayalite content within individual samples, indicating that the degree of thermal metamorphism on the comet, if any, was extremely low. One olivine grain has a high density of dislocations with Burgers vector b = [001], suggesting that the Wild 2 particles experienced hypervelocity impacts before capture. The structural type and composition of pyroxene differ between the samples and within individual samples. Enstatite occurs as ortho- and clinoenstatite, suggesting that the Wild 2 particles contain materials that went through distinct high-temperature and cooling histories. The four Mg-Fe-bearing Si-O glass-rich samples are probably secondary products formed by interaction between melted cometary silicates and melted aerogel during the capture process.

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We analyzed Wild 2 cometary particles returned by the NASA Stradust mission in 2006 by using electron microscopes and synchrotron X-ray diffraction. We found that most particles were composed of amorphous silica with scattering Fe-Ni metal or sulfide particles (about 100 nm), suggesting that they were formed by high temperature during the particle capture process by silica aerogel. We also found that most crystalline phases were submicron olivine and pyroxene. Other minor phases included Mg-Fe carbonate, Mg-chromite, and trydimite. Because the carbonate was associated with amorphous silica and Fe sulfide, we believe that the carbonate was indigenous to the Wild 2 particle. The presence of Fe-Mg carbonate in Wild 2 is very rare, and its occurrence is different from those in hydrous IDPs.

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Among particles ejected from the short-period comet 81P/Wild 2, we found six crystalline particles apparently formed by flash-melting at high temperature, showing igneous texture, mineral compositions, and major and most minor element concentrations that are very similar to chondrules in primitive meteorites derived from asteroids. Oxygen isotope ratios show a wide range of values from −50 to +5‰ in δ¹⁸O nearly along the slope=1 mass independent fractionation line which characterizes chondrules in carbonaceous chondrites that comprise the outer asteroid belt. The presence of chondrules in a short-period comet from the Kuiper belt indicates that chondrules had spread widely over the early solar nebula from inner asteroidal regions to the cold outer regions.

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Dust from comet Wild-2 was captured in Stardust mission by NASA. Impact tracks were formed by hyper velocity impact of cometary dust into silica aerogel collectors with very low density. We have investigated the quantitative 3-D structures and Fe masses of impact tracks by microtomography and XRF using SR at SPring-8 to estimate original features of the cometary dust particles.

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The chemical compositions of unmelted or relict bearing micrometeorites (MMs) survived the atmospheric entry heating, 29 MMs bearing olivines, 10 enstatites, and 4 kamacites, were compared with those in 6 carbonaceous chondrites and an unequilibrated ordinary chondrite, using 103 Antarctic micrometeorites and unequilibrated chondrites. The chemical compositions of unmelted enstatites from 8 micrometeorites are similar to those in CR2, and one is similar to CM2. Those of unmelted olivines had no correlation with those in unequilibrated chondrites, suggesting that they have been affected by the atmospheric entry heating. Those of unmelted FeNi metals are similar to those of CR2. This study suggests that coarse-grained anhydrous minerals in micrometeorites are related to CR2 chondrites.

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We report mineral characterization of the isotopically anomalous material "COS" in the carbonaceous chondrite Acfer 094 using synchrotron radiation X-ray diffraction analysis and transmission electron microscopy. The results show following clear differences between the samples having high Ni content (High-Ni COS) and low Ni content (low-Ni COS); (1) The high-Ni COS grain consists of magnetite + pentlandite, while the low-Ni one consists of magnetite + pyrrhotite. (2) The high-Ni one is an aggregate of magnetite-pentlandite showing a symplectitic texture in tens nm scale, while the low-Ni one is an aggregate consisting of idiomorphic magnetite (∼100nm) and pyrrhotite (∼50nm) grains. We infer that the COS grains were formed by sulfurization and oxidization of metal grains. The chemical and micro-structural differences are probably reflected in the texture and the chemistry of precursor materials before the oxidization.

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Previous study reported that QUE97990 is the least aqueously altered of the CM chondrites. QUE97990 would potentially provide primitive information regarding the formation of CM chondrites. Our goal was to unravel the early aqueous alteration history of these meteorites. Chondrule mesostases in QUE97990 have largely been altered to Mg-Fe serpentine. In many mesostases, however, arrays of parallel, thin lath-shaped crystallites of high-Ca pyroxene, which are primary quenched products, remain unaltered. Chondrules in QUE97990 commonly show topographic depressions (embayments) on their surfaces. Our observations suggest that the embayments containing Fe-Ni metal, PCP, and Fe-Ni sulfide were formed by replacing opaque nodules in their host chondrules. Our observations reveal abundant evidence suggesting that QUE97990 has experienced a significant degree of aqueous alteration.

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CM chondrites are classified as type 2 and experienced progressive aqueous alteration. Some of them were also subjected to thermal metamorphism after aqueous alteration, and heating stages I-IV were proposed. Recently, we showed that the characteristic features of Fe-Ni metal, such as texture and composition, are very sensitive indicators that can be used to classify type 3 ordinary and CO chondrites, and to explore their thermal histories. Here we report our results on Fe-Ni metal in CM chondrites. The metal features are related to the heating stage, indicating the metal composition in CM reflects the secondary heating process after aqueous alteration.

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CAIs in CO3 chondrites contain various amounts of nepheline. Nepheline were formed by secondary alteration (nephelinization). However, the location where the alteration occurred has been controversial. We here present the results of mineralogical and petrographic study of CAIs in 4 CO3 chondrites, NWA1232 consisting of lithology A (subtype 3.4) and B (3.7), Y81020 (3.0), Y82050 (3.2), and Y790992 (3.5). Our goal was to reveal the relationship between the amounts of nepheline in CAIs (the degree of nephelinization) and the metamorphic grade (subtype) of the host chondrites and to determine where the alteration occurred. Our results have revealed that the amounts of nepheline in CAIs tend to increase with increasing subtype of the host chondrites. So, we conclude that the nephelinization in CAIs in CO3 chondrites is the process related to thermal metamorphism in the host chondrites, and occurred on the meteorite parent body.

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CV3 Y-86009 carbonaceous chondrite is a breccia consisting of numerous clasts. Secondary fayalites (Fa>80) occur as grains (5-50 μm) and veins (∼10 × 50 μum) in the host matrix and most clasts. These fayalites show different abundances and Fa compositions in the host matrix and in each clast, and fayalite-veins terminate at the clast boundaries. Thus, the fayalites should have already formed in various conditions of aqueous alteration prior to the Y-86009 breccia formation. Mn-Cr isotope analysis was performed on 15 fayalites in the host matrix and clasts. An absolute age was determined to be 4560 Ma. This age is consistent with other CV3 fayalite formation ages. These results imply that all CV3 fayalites formed by aqueous alteration at the same time in the same single CV3 asteroid.

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The Karoonda CK4 chondrite exhibits pronounced silicate darkening of mainly matrix. Our SEM study showed that the Karoonda matrix contains unusual olivine, with a high density of vesicles and inclusions of mainly magnetite and pentlandite (< 0.1 to 3 μm in diameter). The vesicular and nonvesicular olivines occur as an intermixture, and vesicularity is particularly abundant in regions that exhibit a high degree of silicate darkening. Our TEM study revealed that the vesicular olivine is entirely crystalline and contains a high density of much smaller (< 10 to 100 nm) vesicles and inclusions of mostly pentlandite. In contrast, nonvesicular olivine contains no such inclusions. The results indicate that vesicular olivine is the principal cause of the silicate darkening. We suggest that the vesicular olivine was formed by crystallization of melt that was produced from nonvesicular olivine by shock at a high temperature.

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Two impact melted H chondrites have been studied: Y-791088 has two types of glass with different K-contents, and LAP 02240 has homogeneous glass composition. We compared these meteorites with the impact melted LL chondrite, Y-790964, and the unequilibrated H chondrite, Y-82038 (H3.2-3.4) to clarify the origin of different types of glasses in Y-791088 and LAP 02240. Glasses in Y-790964 have similar textures and composition with that in Y-791088. Glasses in Y-82038 have also heterogeneity in K-content. These features may suggest that the glasses in Y-791088 remain the original heterogeneous K-distributions of host rock. While, the homogeneous glass composition in LAP 02240 suggests that the rock experienced high temperature melting and impact melt flowed and mixed.

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We have developed a new model to calculate the cooling rate by using the Fe-Mg chemical zoning profile of olivine considering diffusional modification during crystal growth. We have applied our model to calculating the cooling rate of olivines in several type II porphyritic olivine chondrules in Semarkona (LL3.00) chondrite. The calculated cooling rates show a wide range, from 0.7°C/h to 2400°C/h, and are different among chondrules. This result suggests that each chondrule formed in different environmental conditions and assembled in Semarkona after chondrule formation. Our calculation results are broadly consistent with experimental results, although the lower limit of the cooling rate is about one order magnitude slower than that by experiments.

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Platy hard C-materials in the heavily shocked Goalpara ureilite were analyzed by Raman spectroscopy and an x-ray powder diffraction method using a Gandolfi camera. The C-materials show weak and broad Raman bands having two mounds at around 1330 and 1600 cm^-1. The x-ray powder diffraction pattern of the C-material shows that it is a mixture of normal and compressed graphites and a diamond. Precise analyses of the x-ray peak positions of the diamond reveal that the diamond has a three-layer stacking sequence of C-sheets as that of natural cubic diamond but C-C distance in a sheet is a little smaller and the space of sheets is a little wider than those of cubic diamond, giving c/a=2.462 in contrast with c/a=2.450 of cubic diamond, where a and c are taken as a primitive hexagonal cell.

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Y-75032 type diogenites and Dho700 are among the most ferroan diogenites. Pyroxenes in these diogenites are high-Ca orthopyroxene and inverted pigeonites. Inverted pigeonites show characteristic inversion textures decomposed from low-Ca and very low-Ca pigeonite. The presence of these pyroxenes indicates that these diogenites crystallized from melts with similar major elements compositions at similar temperatures. However, the bulk REE data and minor element compositions in pyroxenes indicate that they crystallized from melts with different trace element compositions.

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We studied olivines in several Martian meteorites that have brown colored olivine by TEM. As previously reported, we confirmed that NWA2737 olivine contained tiny Fe-Ni metal particles. Similar Fe-Ni metal nano-particles were observed in ALH77005 and Y000097, whereas magnetite nano-particles were observed in LEW88516 and LAR06319. We also tried series of shock experiments and successfully reproduced Fe-Ni metal nano-particles under reducing condition and magnetite nano-particles under oxidizing condition when San Carlos olivine was shocked at higher than 40 GPa ,which is consistent with the estimated shock pressure for Martian meteorites with brown color olivine.

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We analyzed the bulk compositions of chondrules in EH3 and EL3 chondrites. The compositional variation of EH3 chondrules is much wider than that of EL3 chondrules that almost consist of enstatite and plagioclase components. This indicates that the precursor material of EL3 chondrule was nearly homogeneous in composition. We also noticed that chemical and mineralogical compositions in chondrules of various EH3 chondrites are highly variable. Opaque mineralogy is also various in EH3 chondrites. These observations reflect the wide variation of oxygen and sulfur fugacities where the precursor material formed.

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In order to understand kinetic effect on the amorphization process of plagioclase in shocked meteorites, static compression experiments of plagioclase have been performed using an external heated diamond anvil cell. The results of the present study suggest that amorphization pressures at room temperature are ∼37(Ab99), ∼34(Ab89), ∼25 (Ab4) GPa. The amorphization pressure that increases with increasing albite component is consistent with that of shock experiments. The difference in amorphization pressures between static compression in this study and previous shock experiments are not significant. All grains in the Ab99 samples at 27GPa and room temperature were crystalline, while a part of grains in the Ab99 sample at 27 GPa and 170ºC were amorphous. This suggests that the amorphization pressure would decrease with temperature increasing.

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In this study, synthesized forsterite crystals were observed by TEM after shock-recovery experiments. In the 11.7 GPa sample, although the curved dislocations are concentrated at the edge part of the sample, no dislocation are observed at the center part. In the 20.8 GPa sample, dislocations are evenly-distributed. Most dislocations are nearly directed [100] and miner directed [001]. The 34.5 GPa sample consists of various sized sub-grains and irregular shaped cracks. Many dislocations are directed [001]. In the 46.2 GPa sample, there are also irregular cracks and dislocations mainly directed [001]. The Burgers vector of dislocations observed in each sample is [001]. The dislocation densities of 20.8, 34.5 and 46.2 GPa samples are 8.0E+8, 1.3E+9 - 1.5E+10 and 1.4E+10 /cm2, respectively.

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The newly discovered ureilite, labeled TS072 as the field name, contains diamond grains thought to be occurred from graphite. In this study, petrological occurrences, mineralogical textures and characters of carbon minerals were analyzed by polarization microscopy, Raman spectroscopy and XRD analyses to discuss the mechanisms of the occurrence of diamond in detail. Some carbon minerals form "island" in blade-like or amoeboid shaped parts being 0.01-0.3 mm in width. Raman spectra of carbon minerals show that the "island" almost consists of diamond grains. The occurrence of diamond grains suggests that some graphite grains transferred to diamond grains in the blade-like or amoeboid shaped parts, while another grains in the parts reacted with olivine grains and diffused as CO gas.

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Introduction: Most of the phyllosilicates of carbonaceous chondrites experienced aqueous alteration were formed by alteration of olivine. We conducted hydrothermal alteration of olivine to constrain alteration condition. Experiments: Synthesized powder sample of olivine (Fo100, Fo50, Fo20, Fo0) and H₂O (pH=7) were sealed in Au capsule. Our experiments were carried out at temperature 300 degree, at pressure 500 bar and for run duration of 1 week, using hydrothermal synthesizing apparatus. After experiments, we examine recovered samples with XRD and SEM. Results: In XRD pattern from only Fo100, small diffraction peaks of serpentine were detected and no new diffraction peaks were detected from the other samples. SEM observation from Fo100 and Fo50 show that olivine grains have been replaced by serpentine. Discussion: The results of our experiments revealed that Fe-rich olivine tends to have low alteration degree.

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The Niijima and Shikinejima volcanoes consist mainly of rhyolitic lava domes, located at the northern tip of Izu-Mariana arc. The assemblage of hydrous silicate phenocrysts in the Niijima rhyolites (NR) systematically changes with eruption sequence from cummingtonite to biotite (isshiki, 1987). In this study, we present new bulk-chemical data including Shikinejima Rhyolites (SR) and mafic enclaves in NR, aiming at refinement and extension of the petrological model presented by Yoshiki et al. (2006). So far, we find that bulk rock compositions of SR are systematically different from those of NR, suggesting that they were derived from different magma chambers. The enclaves in NR show a differentiation trend, which is not formed by the mixing with NR.

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Radio control plane SKY-1 was developed as a personal observing auxiliary tool for geologists or the research staffs of self-governing body conducting field survey. In this presentation, some impressive movies of SKY-1 will be presented to show the performance and availability of SKY-1.

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Most of the rare metals are used as important index to know the genesis of magma, rocks and minerals in the field of earth scineces, althoug the origins and concentration mechanisms of rare metals have not been well clarified. Because the history of rare metal exoploration is young, we can expect to find new mineral deposits and/or new supply sources.

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The estimated amount of the REO reserves by USGS, 8.8Mt, corresponds to the amount more than 600 times of the annual consumption of REO in 2006. Although the reseves are enough for the limited consumption, it is getting harder for us to import REE into Japan. This is due to inactive REE exploration, which is caused by the inclusion of radioactive elements in REE minerals, the limited number of the deposits with high-grade ores, etc.

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The rare-metals associated granitoids formed mainly in continental and island arcs where "heat" was introduced. The most important point to generate rare-metals enriched granitoids is the presence of ruduced granitoids of older age. It is necessary to have repeated intrusions of magmas over a long period and presence of calcareous rocks for deposition sites to produce a largge-scale rare metal deposits. Surface weathering and placer deposition also helps to enrich metalic elements and minerals.

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There are several types of rare earth deposit. It is thought that among those the ion adsorption type deposit is the most important one. That is because the rare earth elements which are needed, for example, for the magnetic material elements is produced mostly from this type. Therefore, the elucidation of origin of the deposit is essentially important for the exploration of the deposit. However, a few researches regarding the geochemical behavior of the rare earth element in the weathering process of the granite which is the source rock of the ion adsorption type deposit and the existence state of the rare earth element in the weathered granite have been done. Thus, research on geochemical behavior of the rare earth element in the Chinese and Japanese weathered granite was done. The extraction experiments on the rare earth element in the Chinese and Japanese weathered granitic rock soils were carried out.

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Granitoids in southern Thailand show high REE contents, whereas HREE contents are lower than those of the Longnan area, China. Granitoids in southern Thailand show LREE-enriched chondrite-normalized REE pattern. Total REE contents of weathered crust of granitoids in southern Thailand may reach 1000ppm, whereas HREE contents are lower than those of the Longnan area. REE-bearing accessory minerals may be resistant against weathering, and may remain as residual phases. Thus, REE concentration should be elevated by removal of decomposed minerals. HREE contents in greisen and clay veinlet are high, and thus, they show relatively flat chondrite-normalized REE pattern, similar to those of weathern crust in Longnan area. This may be attributed to the leaching of LREE by hydrothermal solution.

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Magmatic and hydrothermal processes relevant to transportation/concentration of rare-metal elements in mantle-deried peridotites will be discussed. Podiform chromitites are important as concentrates of Cr and PGE within the upper mantle. Their characteristics have been explained by melt/peridotite interaction. Recent finding of high-P minerals in some chromitites, however, may necessitate our reconsideration of their genesis. Fe, Ni and PGE are mobile via oxidized S-bearing silicate melts within the mantle wedge. An example their behavor from Avacha peridotite xenolith suite will be shown. Transportation of Ni, Fe and Co released from olivine upon serpentinization may be important. Combined with magmatic intrusion, their sulfides and arsenides are fomed within/around serpentinite masses.

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Understanding element concentration processes via melting is important information not only for magma genesis but also genesis of mineral deposit. Occurrence of alkaline basaltic volcanisms enriched in incompatible trace elements is a common feature of back arcs. Thermo-mechanical evolution of arc - back arc system is crucial to understanding material circulation in the earth, but the origin of the basalts is still controversial. We made systematic geological, petrologic, and geochemical investigations on a Cenozoic back arc volcanism in southwestern Japan to reveal a melting history of a mantle beneath back arc. We firstly revealed that melting beneath back arc occured progressively under condition open to both input and output. Elements are transported from the mantle very efficiently.

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Bauxite and laterite in Boloven plateau, southern Laos consist of gibbsite, goethite and magnetite. Total rare earth element (REE) concentrations of bauxite and laterite are ∼200 ppm and ∼1,000 ppm, respectively. REE-enriched laterite composes of REE-bearing aluminous phosphate mineral. It suggests that formation of phosphate mineral is important process to concentrate REE in laterite.

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Reserves of bismuth (Bi) in individual deposits are rare, and occur as accessory from variable types of hydrothermal deposits. The Bi minerals show great variety of mineral phases which are arisen from the difference of mineralization, and thus have an important key to elucidating the background of ore deposits. Many Bi minerals have been reported from the epithermal deposits in Neogene Green-tuff region, NE Japan. Most of them are the 'xenothermal-type' vein deposits, which are related to Tertiary granitoids at shallower depths. Some Kuroko deposits also include Bi minerals. In this region, detailed studies of Bi minerals by using EPMA analysis are rare. Detailed reexaminations like them are may be expecedt to contribute a future assessment of rare-metals.

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Garnet is most rich in HREE among common rock forming minerals. And it has an important role on the petrogenesis of adakite and TTG (Archean high-Al trondjemite, tonalite and granodiorite), in which HREE are depleted and LREE are enriched. The Jijal Complex is situated in the lowermost part of the Kohistan terrane, northern Pakistan. It is composed of lower peridotite and upper gabbroic units. The peridotite unite is subdivided into dunite, pyroxenite, and garnet pyroxenite and hornblendite zones in ascending order. The garnetite is explained to be generated through dehydration melting of hornblendite, because it is accompanied with the garnet-bearing pyroxenite and hornblendite.

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We report large partition coefficients (Kds) for the REE in cpx from evolved MORB-type and High-Mg andesitic lavas in the Oman ophiolite. Lowering of crystallization temperatures in addition to increasing SiO2 contents in the magmas significantly increases cpx/melt Kd for REE in these systems. Measured Kds in the natural hydrous system show lanthanide tetrad effects, suggesting involvement of complex ions in the structure of melt. Prediction model broadly well reproduced Kds in the natural systems.

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There are many ploymetallic xenothermal veins such as San Jose, Potosi, Tasna, Animas, Siete Suyos, Tatasi and San Vicente mines in the eastern Andes of Bolivia. As indium bearing minerals, roquesite and indium bearing stannite, kesterite, sphalerite, cassiterite and franckeite are found. Roquesite(CuInS2) is found as a granular form in sphalerite. Stannite from Tasna, Animas, Siete Suyos and Tatasi mines has 0.2, 1.2, 0.3 and 5.9 wt. % In, respectively, in maximum. The indium contents of sphalerite from Tasna, Animas, Siete Suyos, Tatasi and San Vicente mines 0.0 to 2.0 wt. %. Cassiterite, franckeite, cylindrite and incaite also contain up to 0.3 wt.% In.

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Heavy metal concentrations of single fluid inclusions trapped in quartz from the hydrothermal W-Sn vein type deposits of the Takatori mine were determined by means of synchrotron X-ray fluorescence (SXRF) technique. These inclusions were analyzed for their metal contents. Doubly polished chips of quartz containing fluid inclusions were prepared and were radiated by synchrotron X-ray for metal analysis at BL-4A, at the Institute of Materials Structure Science of the High Energy Accelerator Research Organization (KEK). Intensities of fluorescent X-ray were applied to the experimentally or theoretically obtained correction equations, and concentrations of metals such as Cu, Zn, Fe, Mn and W were successfully obtained. The ore forming fluid at the early stage is enriched in heavy metals as compared with those of later stages. Considering that the ore-forming fluid in this deposit was derived from granitic magma as was pointed out by oxygen isotopic works, the initial early stage mineralization was caused by the fluid derived from granitic magma with high metal contents and salinities. Then, in this study, we try to measure the Li-Sr isotope of fluid inclusion to investigate the origin of fluid.

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