The Ginzan mine is situated at approximately 40°28' north latitude and 140°48' east longitude. The ore deposits of the Ginzan mine belong to the Kuroko-type. The present paper deals with the characteristics of the mode of occurrence, chemical and mineral compositions, mineral paragenesis of ores, properties of minerals and fluid inclusions.
The ore deposits are composed of several unit orebodies, such as sulphide, Keiko and Sekko-ko bodies. The ores of the sulphide bodies are complicated ores consisting of Kuroko, Oko and Ryukako. Rare minerals found in the ores are electrum, native silver, argentite, pearceite, enargite, cosalite, gersdorffite and so on. The Keiko bodies occur on a small scale in some parts of the ore deposits. The Sekko-ko bodies consist mainly of anhydrite with minor amounts of gypsum.
Bi-, Ni- and Co-content of sulphide ores are approximately 300, 30 and 20 ppm in average respectively. And Sr-content of anhydrite from the sulphide bodies is approximately 7 ppm and that from the Sekko-ko bodies is approximately 12ppm in average.
The ranges of the homogenization temperature and the salinity of fluid inclusions in sphalerite from the sulphide bodies are from 182°to 287°C (241°C in average) and from 2.9 to 7.4 wt.%(equivalent to NaCl).
Some genetical considerations on the ore deposits, and the similarities and differences between the ore mineralogy from the Ginzan ore deposits and that from other Kuroko deposits are also described.

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In this paper, it is described that the estimate of the strength of rock mass can be made by means of shearing rocks between two parallel NX-boreholes.
The outline of this study is as follows;
(1) To estimate the in-situ rock strength, a new borehole-type shear instrument as shown in Fig. 1 has been designed. In the in-situ test, two NX-boreholes are drilled to the side wall of underground opening, and these boreholes are parallel to each other with the distance of 20mm or 25mm. Then the shear instrument is inserted in one side of the two boreholes and the rocks between two parallel boreholes are punched by a shear-edge (20mm×40mm) which is pressed by the oil pump. The shear strength of the rocks can be calculated from the applied shear load and the shearing area as shown in Fig. 5. The shear strength in this test is conveniently termed as “Shear strength index”. The preliminary tests in the laboratory were taken on the relatively homogeneous rock blocks, and from this tests, it will be clear that the relation between the shear strength index and the uniaxial compressive strength of the rock blocks gives essentially straight line as Fig. 7-A. The experimental equation is as follows;S_c=3.14SiwhereS_cis the uniaxial compressive strength (kg/cm²) andS_iis the shear strength index (kg/cm²).
(2) The shear tests were taken at-220mL crosscut of Shakanai mine, Akita prefecture. In this in-situ test, the shear strength indexes were obtained at 43 points in the rock mass, which was consisted of rhyolite with joints. The compressive strength of rock mass can be estimated from the cumulative distribution function of the shear strength indexes with the parameter proposed by B. Kojak. From above proposal, the compressive strength of rock mass, in which the in-situ shear tests were taken, was estimated to be about 530kg/cm².

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In natural gas fields, it is recognized that the surface subsidence is occured due to the pumping of gas-content-water.
So, we studied characteristic behavior of subsidence and available prediction method of subsidence.
The analytical method we showed in this report mainly consists of two parts.One is the seepage analysis with finite element technique to obtain the plan-distribution of piezometric head in gas seams, the other is the calculation of subsidence using the above piezometric head, on the assumption that the ground behaves as a elastic material.
The following results were obtained:
The subsidence in natural gas fields is caused by the decrease of piezometric head in gas seams due to the extraction of gas-content-water, and the subsidence is proportional to the decrease of piezometric head.
And, it is found that the results of our analytical method very agree with those of actual measurements.

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First, the features of the ground movement caused by mining a horizontal coal seam are studied by examining the results of the elasto-plastic analysis carried out by Finite Element Method. It is found that the vertical stress distribution in the coal seam, except near the longwall face, is characterized by the widthc, as shown in Fig. 7, which is defined by equation (9), namely it is the amount of the vertical loadP, newly acts on the coal seam by mining, devided by the initial vertical stresspy. As a matter of course, cis equal to the half length of the excavation unless the contact between the hangingwall and footwall occurs in the mined area. But after the contact, it is approximately proportional to the length of the cave behind the longwall face and to the rigidity of the hangingwall.
Secondary, the mechanism of coal burst at the longwall face are studied by analyzing the stress histories and the plastic behavior of coal in front of the face, in the case that the coal seam is sandwiched by the rigid hangingwall and the relatively soft footwall as like as in the coal burst area of Miike mine. In the case that the internal friction angle of coal is high and the hangingwall and footwall restrict the swelling of coal, it is found, the plastic area in front of the face is reasonably narrow, the center part of the face partially swells and the high stress concentration appears near the face. In this case, if the slides occur along the boundaries among the coal seam, the hangingwall and the footwall, the plastic coal at the face is restrained the vertical compression of which the value is inversely proportional to the rigidity of footwall. When this plastic compression exceeds the limit strain, permissible for coal before the brittle rupture after the yielding, we conclude, the coal is violently destroyed at the face.

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In the studies on the time dependence of size distribution of aggregates, generally, the volume of aggregate is used as internal coordinate, and the similarity variables based on the volume are used for the analysis of self-preserving size spectrum. However, it is one of the most important characteristics of aggregate that the porosity of aggregate changes through the process of aggregate growth.
Hence, in the present paper, seven basic models were proposed concerning the manner of the porosity change, and the most general internal coordinate was determined and the corresponding similarity variables were drawn. Namely, it was made clear that the volume as the internal coordinate and the corresponding similarity variables are usable only in the unchangeable case of the total volume of aggregates in the system, on the other hand, the most general internal coordinate is the weight of aggregate constituents. And also, the similarity variables based on the weight were drawn.

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The adsorption of heavy metal ions (Pb²⁺, Cd²⁺, Cu²⁺, Zn²⁺) on crystalline clay minerals, amorphous minerals and other some soil constituent minerals in acidic solution has been investigated by means of measurements of adsorption and surface area.
The adsorption speed of metal ions on the specimens was relatively high and the equilibrium condition was nearly obtained by shaking for about 5 minutes.
The adsorption was fairly affected by pH of the solution, metal ion concentration and a type of exchangeable cation in the sample. The order in which metal ions were adsorbed on the specimens was as follows; Pb²⁺>>Cu²⁺Cd²⁺>Zn²⁺.
As a result of competitive adsorption of H+, the amount adsorbed of metal ions on the clay in acidic solution had no mutual relation with the surface area. The ratio of internal surface area to total surface area of clay specimens decreased in the order of; 2;1 family clay>1;l family clay, chain structure>amorphous specimens.
In the case of montmorillonite, vermiculite, synthetic allophane and chlorite, the equilibrium data were agreement with Langmuir's adsorption formula in the whole experimental concentration ranges. But the formula was applicable in limited lower concentration ranges concerning kaolinite, halloysite and sericite.
The adsorption capacity of manganese dioxide was nearly equal to it of chlorite.

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The two-stage thermochemical cycle was proposed as described below in this research and experimental studies were made on this cycle. Fe₃O₄+6HC1+H₂S→ 3FeCl₂+4H₂O+S° 3FeCl₂+4H₂O→ Fe₃O₄+6HCl+H₂/H₂S→ H₂+S°
The activation energy for the dissolution of Fe₃0₄ is found to be about 84 kJ/mol under different conditions and the rate is controlled by the surface reaction. It is shown that the rate is dominantly affected by the concentration of ferrousion rather than by the Fe₃+/Fe₂+ ratio in the solution, and the addition of a large amount of ferrous chloride causes a marked acceleration of the dissolution rate.
It is also shown that the reduction of ferric ion with hydrogen sulfide proceeds easily and the rate is controlled by an absorption rate of hydrogen sulfide into the acid solution.
Experimental results on pyrohydrolysis of solid ferrous chloride can be accounted for by considering gaseous FeO as a transient intermediate.

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Completing its historical role the operation of copper blast furnace of the Saganoseki Smelter was terminated in 1970, but it left some interesting data on metal lumps formed at the furnace bottom.
Analysis disclosed the lumps to be speiss containing 100 to 10, 000g/t of Au and Ag and stratified to iron and copper speiss. Solidifying temperatures of iron and copper speisses being approximately 1, 090C°and 800C°respectively, copper speisses precipitated at the lower side.
The distribution coefficient of Au and Ag into matte and speiss (g/t Au (Ag) in matte/g/t Au (Ag) in speiss) is in the range of 1×10^-2to 2×10^-1and 1×10^-1to 5 respectively.The higher Cu% in speiss, the more Au and Ag are distributed into speiss. Except a few data, these results conform well to the range of distribution equilibrium of Au and Ag to matte and speiss system by Gerlach and others.

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