角閃石,黒雲母,白雲母,石英安山岩中の火山ガラスを真空中で段階的に加熱し,各温度で得られた水について,その量と水素同位体比を測定した。角閃石や雲母の水の多くは700°C以上で脱水するが(それぞれFeの量によって違いがある),火山ガラス中の水は80%以上が600°C以下で脱水する。 D/Hの分配係数αは, Feの少ない角閃石 (XFe=0.50) では0.8182 (高温部のみをとる), Feの多い角閃石 (XFe=0.85) では0.8398, Feの少ない黒雲母 (X_Fe=0.44) では0.8680, Feの多い黒雲母 (X_Fe=0.86) では0.8910, 白雲母では0.9565となっている。つまり,いずれも脱水すると次第重い水が残ることになるが,その程度はFeの少ない角閃石がもっとも顕著である。火山ガラスは低温部でも高温部でもαが1に近い(変化が少ない)。しかし,高温では逆に1より大きい場合もある。つまり軽い水が残ることもある。
このよう実験はすぐ火山岩の鉱物やガラスの含水量やD/Hを比較検討するときに使用できないかも知れないが,ある程度の示唆を与えるものと思われる。

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The refractive indices of powdered materials were estimated under a polarizing microscope with an ultralong working distance objective lens of high magnification. The materials with various refractive indices (n_s=1.33-2.66) were suspended in the liquids and the plastic materials with various refractive indices (n_m=1.33-1.78). The image and relief depending on the difference of refractive indices, ?? n=|n_s-n_m|, were eliminated by enlarging the numerical aperture of substage condenser. The nearly proportional relation was found between ?? n and the numerical aperture at which the image and relief of particle could be eliminated, although there were the appreciable deviations due to the various factors such as size and shape of particle, focusing, illumination, thickness of cover glass and numerical aperture of objective lens. However, when these factors were fixed at suitable conditions, ?? n could be estimated with the accuracy less than ± 0.01 for the ?? n range from 0 to 0.25. This procedure will be called tentatively “Relief extinction method” and utilized for estimating the refractive indices of wide range by only a single medium of known refractive index.

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REE and trace metals in seven GSJ rock reference samples were determined by means of sequential type inductively coupled argon plasma/optical emission spectrophotometer (ICP). Separation and preconcentration of the REE and trace metals from an 1g sample digest are achieved by a nitric acid gradient cation exchange and hydrochloric acid anion exchange following Crock and Richte's method. Final solutions are 10 or 20ml for REE analysis and 200ml for trace metal analysis. Relative standard deviation and detection limit of REE analysis are demonstrated by the triplicate analysis of JB-lI and JG-1. REE and trace metal analyses of seven GSJ samples show comparable precision and accuracy, but Cr, Ni, and Zr analyses are not so in some cases.

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