The experimental Raman spectra of monoclinic tridymite and its higher temperature orthorhombic modification were successfully simulated with valence force fields applied to the X-ray determined structural parameters. The normal modes contributing to the corresponding Raman peaks in both the phases share essentially the same types of atomic displacements or bond deformations. In the modes with the wave numbers between 100 and 600 cm⁻¹, predominant are the librations of Si-O-Si planes around Si-Si lines, being followed by bending of Si-O-Si or O-Si-O angles. The librational motions of SiO₄ units around Si appear in the modes below 100 cm⁻¹. Significant bond stretching and compression appear in the modes with wave numbers higher than 700 cm⁻¹: the deformations are classified into 10 types, 7 for Si-O-Si and 3 for SiO₄. Some modes in the highest frequency group between 1150 and 1250 cm⁻¹ show symmetric bond stretching and compression of SiO₄ units, while those between 1000 and 1150 cm⁻¹ antisymmetric stretching and compression of Si-O-Si.
      A low-frequency normal mode is identified to have the polarization vectors of O atoms, which are nearly parallel with the largest principal axes of their thermal ellipsoids. A disorder model is presented to account for the extremely large mean square displacements of O atoms, and a possibility is suggested for the normal mode to boost the hopping of the SiO₄ units between the two orientations.

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Garnet-clinopyroxene amphibolites occur in the mylonite unit structurally at the top of the Takahama metamorphic rocks — a member of the Nagasaki Metamorphic Rocks, western Kyushu, SW Japan. Geothermobarometry applied to an equigranular garnet-clinopyroxene amphibolite, which escaped severe mylonitization, yields the metamorphic condition of 770 ± 70°C and 1.1 ± 0.2 GPa. This condition is comparable with the high-pressure granulite facies, and is much higher-grade than those of the underlying crystalline schists of the Takahama metamorphic rocks that belong to the epidote-glaucophane schist subfacies. Despite the presence of such a gap in metamorphic condition between the crystalline schists and the mylonite unit, nearly identical muscovite K-Ar ages have been obtained from these units, which indicate that both units were juxtaposed at depth before they cooled below the closure temperature of the muscovite K-Ar system.

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A petrographic and mineralogical study of Kobe indicates that it can be classified as a CK4 carbonaceous chondrite. CK chondrites differ from other groups of carbonaceous chondrites, because all normal CK chondrites have been thermally metamorphosed. Olivine and plagioclase are the two most abundant minerals in Kobe. Olivine is very homogeneous in composition, which is consistent with the metamorphic feature of Kobe. However, plagioclase shows large grain to grain compositional variations. The matrix and chondrule mesostases exhibit pronounced silicate darkening. They contain unusual olivine that contains numerous small vesicles (< 0.1-3 μm in diameter) and inclusions (< 0.1-10 μm) of magnetite, pentlandite and minor plagioclase, pyroxene and chlorapatite. The vesicular olivine is particularly abundant in regions that exhibit a high degree of darkening. The vesicular olivine is clearly the principal cause of the silicate darkening. Plagioclase in matrix and chondrule mesostases also contains numerous small vesicles and inclusions of magnetite, pyroxene and minor pentlandite and olivine. The texture and mineralogy of the vesicular olivine and plagioclase suggest that they recrystallized from melts that were produced from olivine and plagioclase in the matrix by shock. We suggest that the shock event occurred at a relatively mild pressure and a high temperature, probably at the state where the meteorite underwent thermal metamorphism.

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