Vuorelainenite was found, as the first occurrence in Japan, from the Kurase mine in the Sanbagawa terrane, Shikoku, Japan. Two types of occurences are observed. A: euhedral 5-50μm crystals, black, opaque with brownish grey reflectance color enclosed in manganoan calcite and rhodochrosite. It often coexists with graphite and manganoan goldmanite, filling among tephroite and rhodonite. Unit cell parameter is a=8.499(1)Å. B: emulsion texture of strings and beads below several μm in size in bementite like minerals. EPMA analyses for euhedral crystals gave TiO₂ 0.00, 0.01; V₂O₃ 65.25, 61.95; Cr₂O₃ 3.42, 3.23; A1₂O₃ 0.14, 0.78; MnO 32.29, 28.26; Fe0 0.16, 5.38; Mg0 0.01, 0.01; Totals 101.27, 99.62 wt%. Their empirical formulae based on Σ Metal=3 are (Mn_0.992Fe_0.005Mg_0.001)Σ_0.998(V_1.898Cr_0.098Al_0.006)Σ_2.002O_4.001and (Mn_0.880Fe_O.165)Σ_1.045(V_1.828Cr_0.094Al_0.033)Σ_{1, 955}O_3.978, respectively. The chemical compositions of the present vuorelainenite is close to the ideal one in comparison with materials hitherto reported. Vuolelainenite seems to have been formed under a low fo₂ condition during the retrogressive metamorphism.

抄録全体を表示

Metal sorption and biomineralization largely reflect the availability of dissolved metals in hydrosphere systems. The metal-loaded bacteria has profound implications for the transfer of metals from the hydrosphere to the sediments. Microorganisms will have played an important role in metal deposition under various temperature conditions. The microorganisms concentrate aqueous dissolved metals onto cell walls and at intracellular sites, during the life cycle, and strongly bind metals during early diagenesis. A sequence is observed in which amorphous cations concentrated at cell walls are progressively transformed to microcrystalline aggregates of carbonate, silicate, Mn-Fe oxides, and clay minerals. The bioprecipitated oxides and oxyhydroxides act as scavengers for heavy metals such as Cu, Pb, Zn, Cd, Sr, and U, in the aqueous toxic-metal dispersion environment. The biomineralization of bacterial cells has been followed in a laboratory simulation by electron microscopy and energy-dispersive X-ray spectroscopy. Several kinds of bacteria were examined for the ability to remove heavy metals from solution. SEM-EDX, TEM, XRF and XRD results indicated that most of metals accumulated at the cell surface as crystalline precipitates after several days of aging.

抄録全体を表示

Meteorites are the most important sample to shed light on the origin of the solar system and planets. In these twenty years, the total number of meteoritic minerals has increased so much, up to about 200. The characteristic features of these minerals reflect on the formation conditions of meteorites. Especially, some minerals indicate the physical conditions at the formation of meteorites. Trace elements and isotopic compositions of meteoritic minerals have been also analyzed. From these data, the processes in the early solar system are reconstructed, such as condensation in the solar nebula, accretion, metamorphism, aqueous alteration, impact process and magmatism in the parent bodies.

抄録全体を表示

Geologic minerals have their own characteristic features in the ultraviolet (UV), visible (Vis), and near infrared (NIR) wavelength regions (e.g., 0.3 to 2.6 μm) of their reflectance spectra. Therefore, meteorites and rocks, which are mixtures of many different minerals, show various, complex, overlapping features in their spectra. Reflectance spectra of asteroids indicate varying surface mineral compositions, some of which are similar to but others are different from meteorites. By classifying asteroids based on their reflectance spectra, their surface materials are shown to vary from high to low temperature materials as they go farther from the Sun. This may imply both that planetesimals in the early solar system had such zoned distribution by (electromagnetic) heating from the Sun or that the inner asteroids grew rapidly enough to make use of short-life radioactive nuclides such as ²⁶Al as a heat source. If we look into the details, however, there are many unresolved questions as to the relationship between asteroids and meteorites such as the issues on the S asteroids and ordinary chondrites.

抄録全体を表示

The accurate X-ray powder data were obtained by a Guinier focusing camera method using monochromatized Xray radiation. The intensities and angles of X-ray diffractions on the Guinier film were measured by automated microphotomete rcontrolled by a personal computer. X-ray diffraction data were obtained by profile fitting employing an asymmetric pseudo-Voigt function of split type using non-linear least squares calculation. Using these data, the relative errors of the cell parameters were estimated to be less than 5·10^-5.

抄録全体を表示