A cupriferous pyritic ore deposit was discovered by recent exploration drilling works at the southern part of the Shimokawa mine. The deposit occurs near the boundary between diabase and phyllite in the eastern part of the so-called diabase complex. The deposit consits of several lenticular orebodies and its total length is about 1800 m. The ore zone strikes NNW and dips east at 50 to 70 degrees. The elongated directions of individual orebodies are slightly oblique to the general strike of diabase body. The orebodies are arranged en echelon fashion. The ores are divided into massive and banded types and their major metallic minerals are pyrite, pyrrhotite, chalcopyrite, and sphalerite.

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This study on the gold veins of the Takatama mine involves statistical analyses and genetic considerations based on various results of the analyses and conventional geological observation.
The factors used for the statistical analyses are strike, dip, width and grade of the veins. Measurements were made at 346 spots 1.5 meters apart in the No. 1 vein, No. 2 vein and No. 4 vein in the No. 2 ore deposit. The general feature of the vein system is shown by stereographic projection of the data on the Schmidt's net. Some features of mineralization were made clear from the correlations between width and strike, width and dip, gold and silver contents, etc. The assay map of the vein shows that silver contents are more variable than gold contents. The attitude of ore shoots were revealed by the distribution of gold contents and gold richness (gold content X width) and the structure of the veins. In the No. 2 vein, the trend of ore shoots passes through the W3-W2 block of the A level to the E1-E3 block of the B level. In the No. 4 vein, the trend of ore shoots passes through the E1-E4 block of the A level to the E5-E7 block of the B level and the E2-E3 block of the A level to the E8-E10 block of the B level. It may be assumed that ore shoots were formed along the currents of ore solution. Thus, the main currents of goldbearing solution were deduced. The ore solution went upward through the cracks in the direction of north-west.

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Argentian pentlandite has been found in the nickel-copper sulphide ores from the Falconbridge Mine in the Sudbury Area of Ontario, Canada. The present argentian pentlandite occurs as a micro-volume mineral up to 200μ across in chalcopyrite, closely associated with normal pentlandite, mackinawite and the unidentified sulphide(s). In reflected light, it has a reddish-brown colour and is isotropic between crossed polars. The development of cleavage traces is not discernible in it. The Vickers microhardness number (VHN) ranges from 146 to 153 kg/mm² at a 25 g load. Its average chemical composition as determined by electron microprobe method is, Ag 13.0, Ni 20.1, Fe 36.1, Cu 0.3, Co 0.0, S 31.3, Total 100.8 (in weight per cent). The corresponding structural formula on the basis of S=8 is, (Ag_0.99 Ni_2.81 Fe_5.30 Cu_0.04)_9.14 S₈, Z=4. From this, atom numbers per unit-cell may be approximated by Ag₄ Ni₁₂, Fe₂₀ S₃₂. The reflections with strong and moderate intensities appearing on the X-ray diffraction pattern are, 3.18 Å (10) (113), 2.03 Å (4) (115, 333) and 1.861 Å (10) (044). It has a face-centered cubic structure with a=10.53 Å, and the powder data are in harmony with the space group Fm3m as normal pentlandite. Its density is calculated as 4.70 g/cm³.
In so far as the present Falconbridge material is concerned, the chemical composition seems to be consistent with the observation by HALL & STEWART (1973) that Ag replaces Ni and Fe only in the octahedrally coordinated 4b sites of pentlandite-type structure.

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Since the chemistry of natural ore-forming solutions from several localities in the world, as well as of model solutions of the Kuroko mineralization in Japan has been elucidated in recent years, it became possible to calculate the amount of some of these solutions. Being provided with the data on the dimensions of the ore deposits and altered aureoles, as well as on the grade of ores and chemical composition of the altered rocks, the calculation was made. It is on the assumption that all of the heavy metals dissolved in the solutions were precipitated and fixed in the deposites, and also that the components that were leached from the wall rocks in the process of terrestrial hydrothermal alteration formed the major dissolved constituents of the solutions. As a result, about 10¹⁰-10¹¹ metric tons of the ore-forming solutions were obtained as the most probable minimum values for the typical Kuroko deposits in the Hokuroku areas. These values are also probable as the amount of the hydrothermal solution which were concerned in the alteration of rocks in some big active and extinct geothermal areas in Japan.
Some genetical considerations are given, in connection with the properties of the ore-forming fluids, on the presistent occurrence of the red ferruginous layers or beds at the top horizons of some stratabound submarine hydrothermal deposits, as well as on the characteristic geological and petrographycal features of the pyrophyllite deposits in Japan.

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The fluid inclusion study of ore deposits and genetically related igneous rocks would suggest the origin of ore-forming fluids and the change of properties of fluids during the mineralization. From this point of view, fluid inclusions in quartz from the Jishakuyama and Koganetsubo ore deposits, quartz of quartz-porphyry and granodiorite of the Akagane mine were investigated by the microscopic observation using a high magnification oil-immersion objective. The size of inclusions were so small that no determination of the homogenization temperature and salinity of inclusions was carried out. The Jishakuyama ore deposit is a vein and disseminated copper ore deposit in quartz-porphyry and skarn, and the Koganetsubo is a scheelite-bearing breccia pipe formed in gabbroic rocks, though most of the ore deposits of the Akagane mine are the skarn-type.
In the Jishakuyama ore deposit, many liquid inclusions and polyphase inclusions which bear a minute opaque mineral were found in vein-quartz, whereas, highly saline inclusions were recognized in quartz-phenocrysts of intensively silicified quartz-porphyry which forms wall-rocks of the ore deposit. In the Koganetsubo ore deposit, however, many CO₂-rich fluid inclusions were found in quartz and scheelite but saline inclusions were not. In two granodioritic stocks, all types of fluid inclusions, that is, saline inclusions, CO₂-rich fluid inclusions and liquid inclusions were found. Saline inclusions were generally not found in quartz-porphyry except in those around the granodioritic stocks, but minute CO₂-rich fluid inclusions were occasionally recognized in samples of quartz-porphyry.
From these results of investigation, it is inferred that the ore-forming fluids of the Jishakuyama ore deposit was hydrothermal solutions having the salinity less than 26 wt.% which succeeded the ascent of highly saline solutions, and that the fluids of the Koganetsubo ore deposit was rich in CO₂ but the CO₂ concentration and the fluid density were various during and after the mineralization. It is also deduced from the distribution of inclusions of various types that these ore-forming fluids would have been originated in some deeper places of the granodioritic stocks.

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Fluid inclusions in granitic rocks from Egypt were investigated to find out any genetic relation between the intrusion of granitic rocks and mineralization. Liquid inclusions with high filling degrees are generally found in "Older Granites" which form batholithic masses with some gaseous inclusions. Polyphase fluid inclusions carrying halite crystals are characteristically recognized in "Younger Granitoids" which generally form stock-like bodies. The coexistence of fluid and gaseous inclusions with various filling degrees is also characteristically observed in this type of granites. Some of these "Younger Granitoids" are genetically related to the tin-tungsten and copper mineralization. It is inferred that apophyses of granitic intrusives are favorable for the concentration of postmagmatic brines and that these stocks intruded into shallow places.

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