As suggested by the results of Russian investigations of geochernical prospecting methods, mercury can be an effective indicator for localization of hydrothermal gold-silver vein deposits that contain trace of mercury minerals. Reviewing the studies on geochemical prospecting methods by means of mercury indicator, the authors improved the analytical method for mercury and obtained good results. For masking disturbing elements in the process of dithizone colorimetry, tests were carried on EDTA and CyDTA as masking agent. Dithizone-carbontetrachloride solution of 0.25 ml containing 0.0005% dithizone is very effective to detect Hg²⁺+ in 0.1μg. Extraction of mercury is favourable for acid solutions of pH 5. For dissolving soil samples aqua rigia is preferable, but the acidity of solutions must be controlled. The method is very cheap in cost and rapidity is remarkable.
Ore deposits of the Okuchi mine are several subparallel groups of gold-silver quartz veins of epithermal type, occurring in the volcanic formation of the Neogene age. Many anomalies found by application of the method to surface soil suggest good representation of the localization of subsurface vein deposits in the area where outcrops are scarce.
The intimate relationship between the surface indications and the corresponding subsurface ore deposits must be the result of hypogene dispersion of mercury, a process of mineralization in favour of structural and lithological conditions.

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Occasionally, normal faults, resulted from the pushing up by magmatic upheaval, are recognized around intrusive igneous masses. They occur not only in the roof rocks surrounding igneous intrusives, but also in the hood parts of the intrusives. These fissures extend along the margins of igneous intrusives and dip away from them. They are synthetic normal faults produced at the time of igneous intrusion, which is often accompanied by folding or warping of the surrounding rocks. Areas sandwiched between this kind of faults are upheaved like horst. The writer has recognized some deposits where the synthetic normal faults were mineralized to copper veins.
These fissures are similar to those accompanied by the intrusive masses of bysmalith type in the mechanism of fissure formation.
In some cases, these synthetic normal faults intersect the tension cracks, nearly at right angle, which were produced by the lateral pressure accompanied by the folding of the surrounding rocks stated above. The writer describes two examples of the case where the mineralizing solutions ascended along the synthetic normal faults and flowed into the intersected tension cracks.

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The mathematical method of cross-correlation function between two columnar sections of drill holes is one of the effective means for analysis of geologic structure. Letting ζ be a phase of the crosscorrelation function, and x be the distance from one drilling station No. i to other No. j, φij (ζ, x) denotes the cross-correlation function, which has more maxima. Continuity of the strata is relative to the maximum values of the function, and ζ co-ordinates which give the maximum values equal to x tan θ, x tan θ±H_f, etc., where θ and H_f show the mean dip angle of the strata and a fault (throw ζ± for a normal fault, -for a. reversed one) respectively. On the other hand, the variation in the function of the variable x is relative to similarity of the strata in the cylindrical co-ordinates.
The mathematical interpertations for drill holes of several mines by computing the cross-correlation function coincide well with the actual geologic structures.

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Small and large ore bodies, irregularly scattered in the fracture zone, are roughly grouped into southern, central and northern bodies, ore shoots of the former two having tendency to converge into a fan shape. In a longitudinal section of the zone, a remarkable zonal arrangement is noticed in regard to the minor contents of Co and Bi, and to the ratio of Cu to As. The nearer the granodiorite, that is situated to south and in the lower horizon, the larger the contents of Co and Bi and the ratio of Cu to As, as shown in Fig. 2 in the text.
Stages of mineralization are : 1st, tourmaline-topaz-scheelite-bismuth minerals-arsenopyrite stage; 2nd, chalcopyrite-arsenopyrite-stage; 3rd, chalcopyrite-pyrite stage. These three stages are regarded as successive without intermission. Afterwards, longitudinal fault cut the pre-existing fracture zone filled with ore bodies, succeeded by formation of calcite veins as the 4th stage.
An intimate relation Shipe between magma behavior and ore mineralization can be exemplified as follows : (a) Invasion of the granodiorite magma causing several shear fracture zones in the country rocks; (b) consolidation of outer cell of the magma, giving rise in intrusion of ore-mineralized solution into certain shear fractures ; (c) further consolidation of intrusives causing tensile faults cutting ore bodies ; and, (d) consolidation of deeper portion of the magma, mineralizing the outer cells of the intrusives.
Zones of ore deposits have certain relations with the wall of intrusives in both Kanagato Mine and Taishu Mine of Tsushima Island, Kyushu. Inclination of the zone of ore deposits is roughly parallel to that of the wall of intrusives in both mines. In the Kanagato hypothermal deposits of Cu, 550-600 meters, and in the Taishu mesothermal deposit of lead and zinc, 1200-1500 meters from the wall belong to the mineralized zone. The top of the former mine and the bottom of the latter mine have the character similar to quartz vein with Cu and As.

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