The Nakatatsu mine, pyrometasomatic lead-zinc deposits in Palaeozoic formations, is located in the. eastern part of Fukui Prefecture, Japan. Intensely folded Palaeozoic formations are angular-uncom-formably overlain by Mesozoic formations, and are imbricated by the faults of an E-W trend. The main plunge of the folds of the Palaeozoic formations is steeply eastward. Predominant contact minerals of the deposits are diopside, hedenbergite and garnet, associated with galena, sphalerite, magnetite and chalcopyrite. An apreciable amount of molybdenite is disseminated throughout the quartz porphyry and the skarn zone. The formation of the northern ore deposits of the mine is strongly controlled by the geologie structure in the vicinity of the mine. Ore deposition is restricted within the Palaeozoic formations, and the following places are favorable for deposition of ores : a) the outerside of shale beds or sheets intercalated in limestone, b) the axial parts of folds which were formed in the Palaeozoic and Mesozoic stages, and c) four groups of fractured zones namely, N65°E, 80°-NW; N25°E, 85°-SW; N20°E, 80°-NW; and N70°W, 85°-SW.
Skarnization and metallic mineralization are closely related to the quartz porphyry. The magnetite deposits occur in the inner zone of skarn masses adjacent to the quartz porphyry, while the sphaleri-te-galena deposits are found in the outer zone. As a result of prospecting since 1955 based on the above-mentioned structural factors in formation of the deposits, new blind ore deposits have been discovered.

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The writer has studied the sedimentation of the Harutori formation which is distributed in the area between Shiranuka and Konbumori in the Kushiro plain, eastern Hokkaido, and laid stress especially on the lateral change of cyclothems referring to its relation with development of coal seams.
In conclusion, it is suggested that some mutual relationships exist between the rock facies and the development of coal seams, and that volcanic activities have causal relationships with the formation of some cyclothems.

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