著者

中野 聰志

出版者

滋賀大学教育学部

雑誌

滋賀大学教育学部紀要 自然科学 (ISSN:13429272)

巻号頁・発行日

no.49, pp.9-17, 1999

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The textural and compositional variations of alkali feldspar in a trachyte from St.Angelo, Ischia island, Italy were examined preliminarily with an X-ray microanalyser. Thefeldspar phenocrysts show complicated textures like flow or ripple, consisting of two alkali feldspars (Or13.5 Ab79 An7.5~Or69 Ab31 An0.3). Their textures are similar to those of the alkali feldspar in a olivine-hedenbergite trachyte from Oki-Dogo island, Japan, although the chemical compostions of the both alkali feldspars are somewhat different in An content. There has been no description on the chemical variation in each individual crystal nor on the detailed textural features of the alkali feldspar.