Fissure patterns of the Nissho Mine, Yamagata Prefecture are radial and concentric around the dome structure of the Middle Miocene formation. The veins mined are in the southern parts of the dome structure, filling the concentric fissures. Ore minerals are sphalerite, galena, chalcopyrite and pyrite, and gangue minerals quartz and calcite. Besides them, a maggrietite-quartz veinlet, in which pyrite and chalcopyrite are observed under the reflected microscope, has been found. Vertical zoning of the main sulfide veins is observed where sphalerite is predominant in the upper part, chalcopyrite has a tendency to increase in the middle part, and pyrite is rich in the lower part. The sphalerite from the lower part has an exsolution texture with chalcopyrite, and etching patterns on the chalcopyrite crystal surfaces suggest that the temperature of formation of the chalcopyrite was rather high in the lower part. And also, of minor elements in sulfide minerals, especially in sphalerite, Bi. In and Sn contents support that the mineralization might have taken place under xenothermal conditions.
The author discussed the close genetical relationship of the stock to formation of the ore deposit.

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The coal of the Takashima colliery has been metamorphosed thermally by the contact effect of the tholeiitic basalt magma. From the several metamorphosed zones in the Hashima and Futago pits of the Takashima colliery have been collected a few series of specimens. These specimens have been analyzed proximately, and, among the results, the correct values of the volatile matter free from moisture and ash and also of fuel ratio have been required. Thermally unaffected bituminous coals from both Hashima and Futago have been heated at temperatures ranging from 200 to 800°C, in an electric oven practically free from air; thus artificially thermal-metamorphosed coals have been made. From the proximate. analyses of various semi-cokes or cokes thus prepared, a diagram has been prepared, indicating the temperature-volatile matter or the temperature-fuel ratio relation. The temperatures of metamorphism. of coal in each contact zone have been estimated from the diagram, and the thermal gradients of the contact zones have been also calculated.
The result of the above experiments suggests that the thermally metamorphosed coal can be used as a geological thermometer, much more effectively than expected.

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To approach the geological problems concerning the S-content of coals, the writer carried out a preliminary investigation on the occurrences of iron sulfide minerals contained in some rocks and coals of the Jooban Tertiary Formations. This paper presents the results of X-ray diffractometry, microscopic observation, etc..
According to the X-ray diffractometry, iron sulfide minerals in the samples used are pyrite. Most of the samples, excepting a few, often contain abundant montmorillonite and a considerable amount of zeolite, along with iron sulfide (cf.Table). Coexistence of these minerals is considered to have resulted from complex conditions as exemplified by the ocourrence of volcanic ashes and marine micro-organisms.
From the microscopical observations of thin sections and of iron sulfide concentrations (cf. Figures), forms of iron sulfide minerals are classified into three types: 1) form of micro-organism (mainly diatom and radiolaria-like shape) and of life product (spawn and excrement), 2) impregnation and irregular massive form, and 3) euhedral or subhedral crystal form. Among these types, pyritization of types 1) and 2) was almost completed by the early stage of deposition, and that of type 3), was fininished by the final stage, or immediately before compaction of the sediments.
It can be imagined that the organismic form of iron sulfide was originated under acidic and reducing conditions resulting from decomposition of micro-organisms, while it is difficult to elucidate the genesis of other types 2) and 3). However, in the discussion of this problem it may be emphasized that the parent material of type 2) was in the process of decomposition and had extremely huge inner surface, that inner part of slime, including such parent materials as above, easily turns to the reducing condition due to difficult water circulation within it, and that type 3) may be able to develop from type 1) and/or type 2).
Moreover, such types as found in rocks are also observed in coals (Figs. 8, 9). Although the original materials of these types found in coals are not clarified in detail in the present study, they may be also similar to those in rocks. At any rate, iron sulfides in coals should be reconsidered morphologically and their genesis must be studied in relation to those in sedimentary rocks.

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1. Alterations of country rocks of some mercury deposits in Hokkaido are generally known as silicification, carbonatization and iron sulfide mineralization, as well as argillitization comprising sericitization, montmorillonitization and kaolinitiiation.
After collecting and interpreting the data by X-ray powder method on alterated country rocks, the author obtained the following results : When the deposits are the vein type, intensity of clay minerals has a peak near the vein but in the impregnation type the intensity shows little change; sericite and montmorillonite occur remarkably in the deposits that accompany mainly cinnabar as ore mineral, whereas kaolinite is intensive in the deposits accompanying much native mercury.
2. In these deposits the range of crystallization of mercurial minerals is relatively wide if we take iron sulfide as the index-mineral.
Cinnabar is generally crystallized from weak-alkaline ore solution in later stage than pyrite, but in the deposits which accompany abundant native mercury, it is found to have been deposited at the same time with native mercury possibly from weak-acidic ore solution during the stage later than marcasite. This is well in accord with the results obtained by the X-ray powder analysis.

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The region in question is composed of the crystalline schist system which constitutes the Iimori syncline and adjoining districts. The Iimori syncline is asymmetric with respect to its stratigraphy and geologic structure, and is subsidiary to the main synclinorium of the Sambagawa geosyncline. The crystalline schist system is characterized by thick basic schists and ultrabasic rocks in the middle part. The system is divided into three formations, namely the Tomobuchi alternation, the Iimori greenschists, and the Ryumon alternation, in ascending order. The Tomobuchi formation is. distributed in the transitional zone between the southern anticlinorium and the Iimori syncline, while the Iimori and the Ryumon formations were deposited in the synclinal zone. The Iimori formation tends to become thicker towards the north, suggesting a downward movement of the geosynclinal basin. Moreover, the Iimori and the Ryumon formations have thickness differing from east to west. This reflects a fluctuation of the downward movement in that direction in the course of sedimentation. In the Iimori syncline the axis of fold plunges towards the west in the eastern part, but towards the east in the weatern part. The upper part of the synclinal structure has a shape similar to the bottom of a ship. The lower part is characterized by a trench-shaped structure forming a root of the syncline, which must have been formed by lateral compression accompanying the downward movement. Therefore, the syncline has a highly disharmonic structure. The Iimori syncline is bordered with flexure zones on both sides, and adjoining the northern flexure zone occurs the Ozu folded zone which is characterized by predominance of minor folds accompanied by axial plane foliation crossing the bedding foliation at high angles. Crystalline schists in the southern anticlinorium belong generally to the greenschist facies, although glaucophane-schists can be found locally. The Iimori syncline and the Ozu folded zone consist of rocks characterized by larger grain-size and the presence of albitic plagioclase porphy-roblasts, and their metamorphic facies is the epidote-amphibolite facies. The grade of metamorphism tends to become higher towards the inner part of the syncline structure.
Many ore deposits of the bedded cupriferous pyritic deposit type have been known from the region. Most of the ore deposits occur within the Iimori greenschists formation stratigraphycally, and within or near the flexture zone of the Iimori syncline tectonically. The limited occurrence of the ore deposits suggests their genetic relationship to the downward movement of the geosynclinal basin and associated submarine volcanism.

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Chin-qua-shih Mine (Cu, Au, Ag), Kufun Mine (Au, Ag) and Butan Mine (Au, Ag) are located close to each other in the northeastern part of Taiwan, and each mine shows different stages of ore mineralization as follows :
In these mines, vertical and horizontal distribution of gangue and ore minerals show zoning which seems to have been formed by repetition of different units in the course of mineralization.

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