In southwestern Japan, the following types of terrain, characterized by different rock formations, are arranged in zones which, are sub-parallel to the Median Tectonic Line. The terrains from north to south are:
(1) Sambagawa and Mikabu terrain : Zone of metamorphic rocks extending along the Median Tectonic Line which trends northeast-southwest, The metamorphic rocks include albite-epidote-chlorite schist, amphibole chlorite-schist, glaucophane schist, piedmontite-quartz schist, stilpnomelane bearing green schist, graphite-quartz schist, sericite-quartz schist. etc., accompanied by basic to ultrabasic igneous rocks. The schists having epidote, chlorite, amphibole, etc. are called green schists.
(2) Chichibu terrain : The Sambagawa and Mikabu terrain grades southward into the Chichibu terrain, which is mainly composed of Carboniferous and Permian sedimentary rocks.
(3) Shimanto terrain : Undifferentiated Mesozoic rocks, probably Triassic to Cretaceous in age.
(4) Nakamura terrain : Undifferentiated formations, Cretaceous-Paleogene in age.
Throughout the Sambagawa and Mikabu terrain, many deposits of cupriferous pyrite (Kieslager-type deposits) occur along the planes of schistosity, frequently as lenticular or bedded, bodies. No particular type of schist constitutes the sole host rock, but green schists are the most common hosts. It, is noteworthy that lenses of piedmontite or hematite quartz schist are frequently associated with the ore bodies.
In the Chichibu, Shimanto, and Nakamura terrains similar deposits occur as lenticular bodies, though they are rarer than in the Sambagawa and Mikabu terrain and most are accompanied by basic rocks. Frequently, ferruginous or manganiferous chert or green rocks form either the hanging wall or the foot wall.
The genesis of the cupriferous pyrite deposits in these terrains has been a frequent topic of discussion among Japanese mining geologists.
The writer concludes on the basis of present knowledge (a) that the cupriferous pyritic deposits in systems were formed by hydrothermal metasomatism genetically related to intrusion of basic igneous rocks and associated folding and dynamometamorphism; (b) that a large part of the green schist in the Sambagawa and Mikabu terrain may have been derived by chloritization, epidotization, and amphibolitization (Fe-Mg metasomatism) of Paleozoic argillaceous, arenaceous, or calcareous sedimentary rocks during intrusion of the basic rocks; and (c) that piedmontite-or hematite-quartz schist or manganiferous or ferruginous quartz schist which forms either the hanging wall or foot wall of the deposit is also of replacement origin, and is genetically related to the basic intrusives.

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