<報文>砂鐵中のマグヘマイトについて

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In the northern part of the Shimokita peninsula, Japan, iron placer deposits are distributed in the Hamada and Tashiro groups of Pliocene series, Noheji group of Pleistocene series and adjacent beach sands. The sands mainly consist of magnetite, hematite, maghemite, limonite, ilmenite, rutile, titanite, hypersthene, hornblende, olivine, quartz, zircon, etc. Maghemites always occur as alteration products formed by the oxidation of magnetites along their grain boundaries, cracks and cleavages. Magnetite, maghemite, ilmenite and hematite form intimate intergrowths, often oriented with each other as follows (host named first, ^*^indicates either may be host) : 1 magnetite-hematite (unmixing and supergene replacement) 2 magnetite-ilmenite^* (unmixing) 3 magnetite-maghemite (supergene replacement) 4 hematite-ilmenite^* (unmixing and selective supergene replacement) 5 maghemite-ilmenite (selective supergene replacement)
1954-03-25