日本アルプスの常念岳の北東で,白亜紀後期～古第三紀の花崗岩中にアルカリ岩の小岩体が発見された。このアルカリ岩は三つのタイプがある。すなわち
タイプI: 閃長岩～石英閃長岩(マイクロクリン-曹長石-エジリンオージヤィト)
タイプII: 石英閃長岩～アルカリ花崗岩(曹長石-石英-マイクロクリン-エジリンオージヤィト)
タイプIII: アルカリ花崗岩(石英-マイクロクリン-曹長石-ヘデン輝石)
このアルカリ岩の産状,岩石学的性質,化学組成を簡単に記載し,それらが交代性起源であると結論した。これらのアルカリ岩は仁科山地の亜アルカリ岩として知られたものと違って,むしろ瀬戸内海地方の閃長岩類に似ている。

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Experiments on the crystal growth of materials belonging to the A1₂O₃-TiO₂ system and on the high-temperature behaviour of natural star-sapphire were made with special reference to the genesis of regular arrangement of the ruitle needle crystals in and on corundum crystals. The crystals were grown by using direct fusion, flux-fusion and hydrothermal methods under the various conditions of temperature, chemical concentration, cooling mode, temperature gradient and oxygen partial pressure. The following results were obtained:
(1) When a thin layer of melt made from TiO₂ powder or from mixture of Al₂O₃ and TiO₂ powder was slowly cooled on (0001) face of corundum substrate, the regular arrangement of acicular rutile crystals was easily formed on the substrate.
(2) The βAl₂TiO₅ crystals grown from the melt on the substrate did not show the regular arrangement.
(3) When crystals of corundum and rutile were synchronously grown by the monotonous slow-cooling of flux-melt in air, no regular intergrowth appeared in both as-grown and aged corundum crystals.
(4) When the intermitent flucutation of temperature was introduced during the slow-cooling in the above method, the conspicuous zonal structure composed of various imperfections appeared in the as-grown corundum crystals. After aging in air, the regular arrangement of rutile appeared on the (0001) faces and along the imperfection zones of corundum crystals.
(5) When rutile was crystallized synchronously with corundum or epitaxially on the (0001) face of corundum from flux-melt in oxygen gas flow or from hydrothermal solution, no regular intergrowth was formed.
(6) In the presence of flux-melt, the regular arrangement of rutile on the corundum substrate was promoted in air or in reducing atmosphere.
(7) Epitaxial growth of corundum on a rutile single crystal did not occur in any of the growth methods mentioned above.
(8) When natural star-sapphires were heated above 1200°C, the regular arrangement of rutile needles fell into disorder from surface to inside and finally disappeared with leaving small gas-bubbles. Ti-atoms tended to migrate predominantly towards the surface and into the small cracks where rutile was recrystallized.
Based on these results and those reported by other authors, critical examinations were made as to such problems as solubility of Ti into corundum, stability of βAl₂TiO₃, removal of Ti from corundum technology for synthesis, mechanical behaviour, epitaxis and natural occurrence. As a result of examinations, it seems that the “precipitation from solidsolution” theory, which is generally accepted as to the genesis of regular intergrowth in star-sapphire, is less plausible. Following two theories were developed on the genesis ofstar-sapphire. (1) Secondary and epitaxial crystallization of rutile along open spaces and imperfection-zones such as shear planes, tension cracks, zonal structure and inclusions, most of which are parallel to (0001) face. TiO₂-component is supplied not only from the external sources, but also from the internal sources such as the imperfection-zones with higher Ti-concentration. (2) Synchronous and parallel growth of corundum and dendritic rutile crystals, being followed by survival of the twig crystals which preserve proper orientation for epitaxis.

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有珠山,伊豆大島,八丈島,新島,十勝岳,一の目潟,城星山,富士山の玄武岩及び,島根県浜田のネフェリナイトのBa及びREEを同位体希釈法で定量し,既に報告されているREEのデータとあわせて,日本列島に産する玄武岩質火山岩のREEパターンの水平方向変化を調べた。軽希土類元素は太平洋側から日本海側にゆくに従って徐々に増加する。重希土類元素の変化は少なく,軽希土類元素の増加は徐々である。又岩系が異なればREEパターンが必ず異なるわけではない。例えば,一の目潟の高アルミナ玄武岩は,アルカリ玄武岩に近い下に凸なREEパターンを示し,太平洋側の新島の高アルミナ玄武岩のREEパターンは,有珠山のソレアイト玄武岩のREEパターンよりも傾きが小さい。このようなREEパターンの変化は,トレンチからの距離に対応していると考えられる。

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