The original igneous rocks of weakly metamorphosed greenstones are basalt-dolerite and limburgite in Mikabu Green Rocks of the Ogose area, and basalt-dolerite-bostonite and limburgite in the Chichibu melange zone of the Agano area, both of Kanto Mountains. Relict phenocrystic clinopyroxenes of basaltic and limburgitic rocks of both areas are chromian augite (Cr₂O₃ 0.4-0.8 wt.%) to chrome augite (Cr₂O₃ more than 0.8 wt.%), but, in general, comparatively poor in TiO₂ (less than 0.1 wt.%). However, limburgitic pyroxenes of the Chichibu melange zone are slightly richer in TiO₂ and Cr₂O₃ and higher in Mg/(Fe+Mg) than those of the Mikabu rocks. The phenocrystic clinopyroxenes are generally similar in Cr₂O₃/TiO₂ ratios to clinopyroxenes of ocean-floor basalts and of peridotite xenoliths derived from the mantle.

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A digital image processing system composed of personal computer, TV camera and image digitizing board, was developed for the analysis of optical properties of ore minerals under the microscope. The system can quantitatively carry out surface, line and point analyses of brightness and chromaticities in minerals.
Under reflected light, chromaticities of electrum were measured using the system. Good correlations were observed between Ag contents and chromaticities. Brightness and chromaticities of sphalerite with color zoning was also measured under transmitted light. They suggest that the color in sphalerite changes from pale yellow to orange with increase of Sb and Cd contents. This method is applicable for various studies on mineral textures.

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The gallium content of 21 plutonic rocks of the Miocene ring complex of the Cape Ashizuri, Kohchi Prefecture, Southwest Japan, has been determined by X-ray fluorescence spectrometry. From the correlation of gallium with the previously reported aluminium data, we have suggested two contrastive trends of differentiation, high-Ga trend and low-Ga trend. The former trend was operative during the evolution of the cogenetic syenitic rocks, i.e., melanocratic syenite→quartz yenite→alkali granite→quartz syenite porphyry, all of which occur in the inner zone of the ring complex. The Ga values are almost constant or slightly increasing (23 to 27 ppm) but in the last stage increase abruptly up to 33 ppm in the quartz syenite porphyry having the characteristics of a residue of syenitic magma. In contrast, the latter trend is exhibited by gabbroic rocks, coarse-grained quartz syenite, rapakivi granite and coarse-grained biotite granite occurring in the outer zone of the complex, and the Ga values slightly decrease from 23 to 15 ppm as the Al₂O₃ content decreases.
The qualitative analyses revealed that the gallium has been concentrated mainly in La-Ce-Nb-F minerals in the quartz syenite porphyry. The rocks on the high-Ga trend have higher fluorine content than those on the low-Ga trend, and the Ga/Al ratio of some A-type granitoids in the world shows a positive correlation with fluorine content. These data indicate that the two differentiation trends of the Ashizuri plutonic rocks have been caused by the difference of fluorine content in the magma.

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三宅島産灰長石の赤色部に点在する微小な暗褐色の鉱物は, EPMAと,ガンドルフィー機構を装着した微小部強力X線回折装置を用いて,自然銅と同定された。この暗褐色鉱物は大きさ数十μmの薄板状を呈し,灰長石の ( ?? 04) 面に平行に点在する。 EPMAによる分析では, Cu元素のみが検出されたので,そのLα線のケミカルシフトを測定し,金属銅,自然銅,赤銅鉱,黒銅鉱と比較したところ,薄板状鉱物のLα線のピークは,金属銅と自然銅のそれに一致した。さらに,その薄片試料から約40 μmの目的結晶を剥離して,ガンドルフィー機構を装置した微小部強力X線回折装置(木股ら, 1990) により測定した結果,灰長石以外の回折線はJCCPDSファイルの金属銅と同定され,その格子定数も決定された。この灰長石中の自然銅は, Cu以外の元素を含まないこと,その結晶形態と配列関係から,灰長石からの離溶により生じたと考えられる。

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日本海北東部に位置する礼文島において,中期中新世のアルカリドレライトが発見された。このドレライトは斜長石,チタンオージャイト,及びイルメナイトからなり, Na₂O, TiO₂, P₂O₅, Fe₂O₃に富む。そのK-Ar年代は18.2±1.2 Maであり,礼文島では日本海の形成時期にアルカリ系列の火成活動が行われたことを示す。

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