The Hosokura mine is one of the largest lead and zinc mines in Japan. The mine lies in the eastern margin of so called "green tuff region" in northeastern Honshu, and the mine area is composed mainly of propylite, rhyolite, green tuff and tuffaceous sandstone, all of which belong to the Miocene formation. The ore deposit is of the fissure-filling vein type.
Considering the following facts :
(1) the mine location on geological structure in the green tuff region,
(2) the vein pattern,
(3) the direction of arrangements and shapes of igneous bodies,
(4) the gravity anomalies ;
the main structural directions of N-S, E-W NW-SE and NE-SW are presumed in the pre-Miocene basement. The sedimentary environment and the vein systems are also under the influence of the four structural directions mentioned above.

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As a result of the intensive exploration, based upon the studies of geological structure and mode of mineralization, more than ten new ore-bodies were discovered in the external zone around the known mineralized tracts of the Mozumi mining area, the Kamioka mines. At present, the zone involves the following ore-bodies : S No.6 to No.9, E No.2 to No.4, NE Nos.1 and 2, N No.21 to 23 and so on.
The discovery of these ore-bodies has brought about 2, 500, 000 tons of crude ores. In the near future another 4, 000, 000 tons of probable ore reserves may be expected.
On geological structure of the area, the followings have been clarified;
1) It is most probable that there is a large synclinorium in the Mozumi mining area. Consequently, it is considered that two major groups of ore-bodies, the Ikenoyama and the Nakagoya, might be emplaced in the limestone bed belonging to the same horizon.
2) The mode of distribution of the Tetori Members and Hida gneiss complex and geological relationship between them have been disclosed.
3) The geological significance of Kita No.20 fault can be well understood.
4) The three blocks consisting of gneiss complex were discriminated and also their mutual geological relationships have been clarified, namely,
a) The first block of the Ikenoyama area is situated at the hanging-wall side of the Kita No. 20 fault.
b) The second block is bounded by the Yokoyama overthrust and the Kita No.20 fault.
c) The third block develops at the foot-wall side of the Yokoyama overthrust, and is covered by the Tetori Member on the surface.
On the mode of mineralization, the following facts have been clarified ;
1) The zonal distribution of ores in each ore body is clearly recognized, from the center outward as follows :
Ore veins and stringers→Shiroji high-grade ore→Pb-Zn Mokuji ore→Cu-bearing Mokuji ore→Barren Mokuji.
2) From the field relations, it seems reasonable to consider that the mineralization is closely related to the igneous activity of the Namaridani granite prophyry which develops north to the mineralized zone.
3) The role of fissures for mineralization has been clearly disclosed. At the higher level, fissures relating to the Nanagohi fault played an important role as channelways of ore-forming fluid ; the same as at the lower level these relating to the Kita No.20 fault must be considered as the main channelways.
Summarizing the above, it is inferred that the mineralized zone may be enlarged downwards with increasing depth.

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The Hanawa mine is situated at the western part of the so-called Towada basin, where it forms the Sotoyama local basin.
As the results of the geological survey, gravimetric survey and drilling, the writers conclude that the period of the Sotoyama basin's completion was the Funakawa age.
The ore deposit of the Hanawa mine belongs to the Kuroko type, and is divided into three main ore deposits, namely, the Motoyama, the Aketooshi and the Onnataira. Among them, the Motoyamaa ore deposit is peculiar in its vertical distribution of the unit ore bodies.
The results of the latest exploration revealed that the structure of the Motoyama ore deposit showing a deep trough accompanied by the inverted strata was shaped at the Funakawa age. Such a structure might be due to the movement which created the Sotoyama local basin.

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The recent exploration in the neighbouring areas of the Shimokawa Mine, brought about several geological data which made the discovery of new orebodies possible in the deeper part of the producing area and the Nakanosawa area.
The important geological data obtained are as follows:
1. The ore deposits occur near the boundary between diabase and slate at, the eastern part of the so-called diabase complex. Diabase and slate strike at NNW and dip 50-70°E.
2. Diabase can be classified into two types; the "effusive type" and the "intrusive type". There is no correlation between the occurrence of the ore deposits and the types of diabase.
3. The ore deposits are slightly oblique to the direction of diabase. They are arranged "en echelon".
4. The wall rocks near the ore bodies is intensely sheared and is characterized by amphibolitization, chloritization and silicification-sericitization.
5. The ore bodies consist of some respective bonanzas which are oblique to the shoot of the ore bodies. The bonanzas are arranged "en echplon".

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Successful results have been obtained by the present I.P. prospecting at all the observed area in Andes Copper Belt, Chile, because the writers could overcome the problems of the electrical earth resistance about which they had worried at the beginning.
Several frequency effect anomalies were found in these areas. Among them, the most promising anomaly was recognized at B-65 area, judging from the scale, shape and distribution of resistivity, and the anomaly of metal conduction factor.
The intensity of anomaly in B-66-S area was slightly smaller than that of B-65 area. Namely, in this area, the relations between the F.E. anomalies and the distribution of resistivity are not so clear as in the former area, although there are several F.E. anomalies as mentioned above.
Compared with the former two areas, the anomalies in C-134 area were not remarkable considering from the shape and extentions. These anomalies can be presumably due to mineralization near surface.
Summarizing the above, the results will be given as follows :
(1) In the case of B-65 area, two F.E. anomalies are found. Both of them seem to have closer relations each other. The most promising anomalies may be in the areas from the traverse N3 to the traverse 0 around the station 0.
(2) In the case of B-66-S area, F.E. anomalies are found in the areas from the traverse N8 to the traverse 0 around the station W6. The most remarkable one is recognized in the traverse N2.
(3) Finally, in the case of C-134 area, some smaller anomalies are found at the station S2 in the traverse W6 and the station S5 in the traverse 0, respectively. However, these anomalies may be not so important judging from the scale.

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For one month from June to July in 1970, ground geophysical surveys, induced polarization (I.P.) and self-potential (S.P.) methods, were carried out in the area of Mamut Mine by the present writers under the contract with Overseas Mineral Resources Development Co., Ltd.
In general, the I.P. and the S.P. methods can not distinguish economic sulphides, e⋅g., chalcopyrite from pyrite, but the I.P. anomaly can indicates the percentage of the total sulphides. These methods are especially applicable for the area rich in chalcopyrite and pyrite.
These surveys were carried out for determining the volume of the known ore body and prospecting new mineralized zones of the porphyry copper-type deposits at Mamut.
The volume and dip of the ore deposit of the Mamut-2 mine were deduced trom the detailed I.P. data. In addition, adaptability of the S.P. method to the disseminated sulphides deposits with intensely oxidized crust was confirmed. This environment can be expected in a hot and highly humid area with a shallow ground-water level.

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The Daikoku deposit of the Ainai mine belongs to "Kuroko"-type deposit, having zones of siliceous ore, gypsum, and stratified ores.
In this deposit, stratified sulfide ores are grouped into two types, depending on their modes of occurences.
In the southern part, the ore bodies consist of, in the ascending order, siliceous ore, stratified yellow ore and black ore. These stratified sulfide ores are very compact, and have banded texture of pyrite and chalcopyrite in some cases.
On the other hand, in the northern part of the deposit, the bedded sulfide ores contain fragments of compact black ore and yellow ore in the matrix consisting of cubic pyrite, crystal barite and clay material. And the ores can be classified into two types ; namely, the "massive part" with coarse grained and unsorted ore fragments, and the "bedded part" with fine grained and bedded material.
In the latter case, several units of vertical sorting of ore fragments and pyrite crystals are observed. In each unit, grain size of ore fragments and cubic pyrite decreases from the lower horizon to the upper horizon. In the upper part clay minerals are predominant. Also, "sole mark" and "imbrication" structure, which are very common in pyroclastic flow sediments with submarine turbidity currents, are found in many places of the ore deposit.
It is suggested for the evidences mentioned above that the graded ores in the northern part of the Daikoku deposit were settled secondarily by the submarine currents from the original ore bodies deposited primarily at sea bottom.
Thus, it is expected that black ores may be found in the northeastern extention of the Daikoku deposit judging from the analysis of geologic structures and "the study of sorting of ores.

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The copper deposits, consisting of chalcopyrite, pyrite, sphalerite, galena, quartz, calcite, sericite and others, in the main area of the Kishu Mine occur in the Okochi 'the Itaya and the Taketo formations of the Miocene Miyai Group. They are mainly composed of sandstone, and sandstone and shale.
The Miyai Group surrounding the main ore-bearing area has a general strike of N20-40°E and a dip of 10-30°E. The main ore-bearing area is situated in a dome of a large basin of the Miyai. Group. The long axis of the dome is parallel to the general strike of the Miyai Group.
Vein fissures of the main mining district are grouped in the following three sets according to the strike directions: i. e N-S, E-W and NW-SE. Intersections between two sets of fissures of the N-S group and the E-W or NW-SE group, can be regarded as the channelways of mineralizing solutions and mineralization centers. The most important intersection is situated in the vicinity of the dome where Josen No. 20 vein meets Josen 9-level North Cross-cut.
Five mineralization stages can be recognized. i.e Py, Cu-Py, Pb-Zn, Au-Ag and calcite stages. There are two types of copper ores. The one is associated with chlorite formed during the Cu-Py stage and the other with sericite formed during the Pb-Zn stage. The latter's deposition centers are generally beneath the former's.
Silicification, chloritization and sericitization are recongnized as wall-rock alterations.
The Cl^- content distribution in the deep seated ground-water in the mine well reflects in the geologic structure.
Filling temperatures of the minerals mainly measured by decrepitation method are 172-318°C in chalcopyrite, and 160-330°C in pyrite.

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The Ikuno mine is located in the Inner Zone of Southwest Japan and is well-known, together with the Akenobe mine, as one of the typical xenothermal deposits. Geology of this area is composed of the Tamba group, early Permian, and the Ikuno group, late Cretaceous to Paleogene, which consists. of various volcanic and pyroclastic rocks from rhyolitic to basaltic. Ore deposits are polymetallic veins in the Ikuno group and its accompanying intrusive rocks, showing the typical zonal arrangement, that. is, the polymetallic zone in the central part and the gold-silver zone in the outer part.
The writers made observation on the recently-developed gold-silver veins (Nishi-rokugo vein of the Tasei vein group, Koei vein of the Kanagase vein group, etc.) with the naked eye and under the microscope, and they were able to clarify characteristics of the veins. From the results of these studies and the geochemical survey carried out for the Aokusa vein group, some possibilities of discovery of new gold-silver veins have been obtained.

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The collecting test of the continuous line bucket was carried out from August to September, 1970, at the sea near Tahiti Island. The outline of the results are as follows :
1) The test was successful in the collecting manganese nodules from the bottom of 3, 760 meters in depth by the continuous line bucket method.
2) A belt rich in manganese nodules was discovered at the bottom of the Central Pacific Ocean. The manganese nodules contain copper and nickel in appreciable amount.
3) Total weight of manganese nodule collected in the present work was about 2 tons.

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Under the contract with Overseas Mineral Resources Development Company Limited, a prospecting project by diamond drillings in the Mamut mine, Sabah, Malaysia, was carried out as a joint venture of Sumiko Consultants Co., Ltd., and Nikko Exploration and Development Co., Ltd., during the period of fifteen months from June, 1968 to August, 1969.
The project was divided into two stages, the first and the second. The outline of these stages is shown in the following table :
1 st Stage
2 nd Stage
(from June to November, 1968)
(from December, 1968 to August, 1969)
No. of holes 21 55
Total length 4, 297m 11, 424m
Drilling length per one shift 7.03m 7.95m
Core recovery 81.8% 83.0%
In pursuing the works of these stages, the following considerations were made :
Transportation : All of the drilling machines and tools were transported by the cableways because of rugged topography and thick vegetation.
Drilling Machine : High speed-type machines which have good efficiency for hard rocks were used. Diamond bits were selected carefully in accordance with the hardness of rocks.
Cutting Oil and Chemical Grout : Some amounts of cutting oil were added in circulating water in order to increase the cutting efficiency. The wall was protected from caving by chemical grout in many fractured zones.

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The relations between a mine and groundwater include many problems. The most urgent thing of them for mining engineers or geologists is how to procure ore dressing water or drinking water, that is to say, how to develop groundwater at a virgin area, where a mine is to be developed.
The first step to develop groundwater in the area are collection and arrangement of the existing literatures, and data of topographical and geological surveying, geophysical prospecting, and so on. Nevertheless, they are not sufficient without deep drilling.
Until now, the rope drilling machine has been widely used for drilling water-wells for number of years. The rotary-type drilling machine is, however, more efficient in deep drilling in a short period.
As a rule, mud-water is necessary for the rotary drilling method, therefore, in drilling at an arid area where drilling water is not available, dry drilling (air drilling) should be carried out at first till sufficient quantity of mud-water for the rotary drilling machine is available.

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