Gobbinsite occurs as fibrous crystal in the amygdales of altered trachybasalt from Kuniga, Dozen, Oki Islands, Shimane Prefecture, Japan. The average chemical composition by EDS analyses leads to the empirical formula, Na4.09Ca0.75K0.23Sr0.07Al5.92Fe0.01Si10.07O32·nH2O on the basis of O=32 in anhydrous part. The unit cell parameters calculated from the X-ray powder diffraction data are a=10.078(3), b=9.785(2) and c=10.149(3) Å. The correct X-ray powder diffraction data for gobbinsite as orthorhombic cell are indicated, because the previous X-ray powder diffraction data are confused in the point of the crystal system and cell parameters.
Tamba granitoids, small stocks in northern Kyoto, have adakitic character, i.e., highly Sr/Y and lower Y contents than surrounding granitoids (ilmenite-series) of the San'yo belt and granitoids (ilmenite-series) of the southerly Ryoke belt. The adakitic granitoids including the both ilmenite-series and magnetite-series are further classified into two groups, typical adakite same as Cenozoic type locality and transitional adakite, based on their Ni and Cr contents. Known hornblende and biotite K-Ar ages of the adakitic granitoids are 101-107 Ma, corresponding with those of high magnesian andesite in the Tamba area and older than those (70-80 Ma) of granitoids of other San'yo belt and Ryoke belt. Since the crustal thickness of the San'yo belt in Mid-Cretaceous is not expected to have been thicker than that of present days (37 km), the adakitic Tamba granitoids magma is considered to have been produced by slab melting and subsequent interaction between the magma and host rocks in the wedge mantle.
In situ electron microscope observation is a very useful technique to observe directly structural changes of materials. A direct heating type hot stage for use with a high resolution transmission electron microscope has been developed. The hot stage allows high resolution transmission electron microscopy observation at high temperatures above 1000°C. This paper describes the performance of the hot stage and its application to a study of a formation and sintering of SiC crystals at 1500°C. SiC crystal growth during sintering was observed at near atomic resolution.
Biomineralization is interpreted to be the mineral deposition occurred under the influence of organisms. To study biomineralization, it is quite important to perform biological techniques besides mineralogical ones, because biominerals are closely related to cells and organic materials. This article describes a series of biological techniques for biomineralization study using transmission electron microscopy, and shows some examples.