The Poronai Formation which is more than 1000 m thick and consists of massive, unstratified and extremely monotonous mudstone, covers a large area of the Yubari district, Ishikari Coal field. Therefore, to make clear the highly complex structure of the district, subdivision of the formation was of prime importance.
H. Onishi, who has been engaged in detailed mapping since 1947, succeeded in 1950 with his assistants to subdivide the poronai Formation into 7 biostratigraphical zones, statistically treating mega fossils, marl lenses, glauconite, etc.
Since the method of zoning was thus applied, the accuracy of zone-boundary was improved and finally 9 zones were established. This method is easily applied to the interpretation of drilling logs and tunnel geology and actually benefits the understanding of geologic structure of the district.

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The ore deposit of the Nishinokawa Mine is of a bedded cupriferous pyritic type (so-called "Kieslager type"), occurring conformably or concordantly in the green schist formation in the central part of the Sambagawa metamorphic terrain of Shikoku Island. There are two types of ore shoots having different plunges. The one in the upper to middle part of the deposit plunges to S 80° E (25°), while the other in the middle to lower part abruptly changes its trend to S 45° W (25°). Then, two differently orientated goaves overlapping each other can be seen in some places in the underground map. The structural features mentioned-above are remarkably distinctive, because, generally speaking, most Kieslagers in the terrain have simple ore shoots elongated in one direction.
The writer consider that the peculiar structure has been formed by the "junction" of "primary" ore shoot having an E-W trend and later "abnormal folding zone" having a NE-SW trend along which "secondary" ore shoot occurred. Mechanism of the formation of the "secondary" ore shoot or bonanza can be schematically explained by folding up of original ore bed in the folding zone.
It has been described that shape of ore shoot of Kieslager is "controlled" by two or more sets of folding systems, but in most cases the influence of folding system of second or third order is rather slight on formation of ore shoot. In the case of the Nishinokawa Mine, howeuer, the influence of second stage folding was so remarkable that not only the "primary" ore shoot was formed by earlier folding, but also the "secondary" ore shoot along the later "abnormal folding zone".

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The Chin-qua-shih Mine is one of the large metal mines in northeastern Taiwan. Geologically the Chin-qua-shih area is composed of sedimentary rocks of Neogene Tertiary and dacite intruding the former.
The Cin-qua-shih Mine ore deposits are found in these rocks and consist of gold, silver and copper minerals. Each of these ore bodies is controlled by faults and dacite intrusion. They are classified into the following types by the mechanism of fissure formation:
Vein type……Honzan, Heikomyaku, Daisan-chojen, etc.
Massive type……Daini-chojen, Sosekizan, Sosan, etc.
The process of mineralization seems to have been repeated as follows:
1) Formation of weak zones which may have been fault zones caused by folding.
2) Intrusion of dacite.
3) I st fissuring and mineralization of pyrite, alunite and silicification almost without gold, silver and copper minerals.
4) II nd fissuring and mineralization of gold and silver-bearing enargite.
5) III rd fissuring and mineralization of limonite, accompanied by gold and silver minerals.

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Microscopical and electron probe microanalyzer (EPMA) studies on copper ores from the Komori mine, Kyoto prefecture disclosed occurrences of nickel-bearing mackinawite (Cu4.0%, Fe52.1%, Ni5.6%, Co1.0-2.0%) usually associated with chalcopyrite and of cobalt-bearing pentlandite (Cu0.1%, Fe 28.7%, Ni25.9%, Co15.8%) generally with cubanite and pyrrhotite.

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The Komori mine is located in Kyoto prefecture in the western part of Japan. In the ore minerals, of the Komori mine, the minerals belonging to Cu-Fe-S system show interesting ex-solution textures under the reflection microscope. The ores having ex-solution textures are divided into two types, that is, the ores with lamellar texture and those with non-lamellar texture. The ores having lamellar texture are further divided into the following five subtypes as shown in the table in p. 340
subtype 1 has the lamellar texture of chalcopyrite-cubanite.
subtype 2 has chalcopyrite-cubanite lamellar texture ; in the cubanite lamellar the unmixed pyrrhotite is contained in crystallographic intergrowth.
subtype 3 has chalcopyrite-cubanite lamella rtexture; in the cubanite the lamellar unmixed pyrrhotite is contained in regular intergrowth, and the pyrrhotite has the unmixed cobalt-bearing pentlandite which further contains unmixed nickel-bearing mackinawite in crystallographic intergrowth.
subtype 4 has chalcopyrite-cubanite, lamellar texture ; in the cubanite lamellar the unmixed cobaltbearing pentlandite is contained in regular intergrowth.
subtype 5 has chalcopyrite-cubanite lamellar texture ; in the chalcopyrite lamellar the unmixed nickel-bearing mackinawite is contained in crystallographic intergrowth.
The ore having non-lamellar texture consists of granular cubanite and chalcopyrite, the former contains generally cobalt-bearing pentlandite in crystallographic intergrowth, while the latter contains nickel-bearing mackinawite in regular intergrowth.
These ex-solution textures are interpreted probably by Borchert's concept that presumed chalcopyrite-chalcopyrrhotite solid solutions, and by the presumption of chalcopyrite-cubanite solid solution.

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The Akiyoshi limestone plateau in western Japan is covered with terra rossa (Fe=10.8%) of about 5 m thick for one-third of the whole area. In the terra rossa, we find some nodules of limonite ore with Fe content 52%, and high aluminum clay with SiO₂ 20-25%, AL₂O₃ 40-44%, Fe₂O₃ 9.3%, H₂O+18.9-22%, whore chemical composition indicates beauxite. The writer supposes the origin of limonite ore and aluminum clay as weathering residual product limestone, produced during the late Tertiary peneplanation period under either subtropical or tropical climate. Economic value of these ores should be studied in the future.

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The nickname "Green Tuff" had been used by Japanese geologists for the Miocene volcanic complex which is characteristic to the inner zone of Japan. However, the area now called the Green Tuff region in Japan is enlarged as shown in Fig. 1. This area is one of the most important mining provinces of Japan in both of metal and oil. In this article, outline of the geological history in this region is explained, attaching importance to northeastern Japan, especially to the Akita district. In the Akita district, the Miocene sediments are stratigraphically divided into seven stages, and they are roughly enumerated as shown in the following table :

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