With the rapid growth of Japanese economy, her domestic demands for non-ferrous metals have been increasing every year with a large portion of the supply which depends from the overseas mineral resources. Accordingly, the exploration and development of overseas mineral resources are reflected by the consensus of the national opinion.
Under these circumstances, the exploration and development which have been taken since 1952 are carried out systematically in much larger scale today.

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A copper development project in Bougainville Island, located in the Solomon Islands, represents one of the world's largest surface mining operations, which will be brqught into production in 1972.
Porphyry copper deposits occur in the Panguna andesite complex and in the marginal part of Kawerong diorite intrusives of the, Neogene Period.
The technical mission organized by several Japanese mining companies was sent to Bougainville in July, 1969, for the purpose of investigating the feasibility of this project. The mission was provided with vast amounts of valuable and accurate informations and data on the project by technical staff of Bougainville Copper Pty., Ltd., (wholly owned by the C.R.A. group), and by consultants of its parent. company, R.T.Z. London, who have worked on the Bougainville project from the exploratory stages.
This report describes an outline of Bougainville Copper's procedure for calculating the ore reserves of Bougainville mine using a digital computer. In addition, it introduces the results of an experiment conducted by the authors using all the available original data in an attempt to confirm Bougainville Copper's figures. Analytical method used by the writers differs somewhat from that of Bougainville Copper Pty., Ltd.

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Two-dimentional trend surface analysis was applied to assign a copper grade to unit ore blocks for the ore reserve estimation at the Lornex mine by the Japanese FR survey team. The main purpose of the analysis was simply to examine the ore reserve calculation from an investor's point of view and was never to design or modify the mining pits.
The Lornex feasibility report describes that the trend in distribution of copper and molybdenum grades is strongly governed by structural patterns, Therefore, the method which we use should be the one that could be applicable suitably to such characteristics features. Because of the limitation of time available, the examination was started before the actual observation of ore deposits at the mine site.
The total number of drill-holes is 87 of which 66 holes are located within the pit limit, although this number seems comparatively small as compared with the size of ore body, of which reported ore reserves is 294 million short tons.
The principal procedure adopted was as follows: The ore deposit was divided into 29 slices, which were horizontally 80-feet apart in E-W direction and approximately parallel to the general trends of fissure system that were reported to control the grade pattern. The copper grades of each drill-hole intersection with individual slices were projected on the N-S longitudinal sections. Then, the two-dimensional trend surface analysis was carried out for each slice. To determine the most adequate surfaces, the variance analysis was adopted using the Ist to 4th-order polynominals progres-sively. Grades obtained from such computed surfaces were assigned to each unit ore blocks which were defined as the 80-feet grid on the N-S longitudinal sections.
The result obtained by this method indicated a fairly well agreement with one that described in the feasibility report, although the authors' result was slightly large in tonnage and slightly low in grade at the same cut-off. The main reason for this difference seems to be caused by the inherent nature of the two methods; in the trend surface analysis the high-grade intersections are tend to be cut off by smoothing, whereas in the Lornex method the high-grade0 intersections in the grade trend cover such large area as 400×400 feet. The computed trend surface indicated that the ore body could be interpreted as an aggregate of three lenticular high-grade blocks en échelon.
This method may be applicable with more correctness to an ore deposit which has, or is anticipated to have grade trends, when number of DDHs is comparatively small. But when number of DDHS is large enough, other methods such as rolling mean, distance-weighting on slices and etc may be more adequate. This method can be useful also for the interpretation of internal structures of an ore body. The three-dimensional trend surface analysis might be applicable on the Lornex ore body itself.

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The Mamut mine is seven miles north of Ranau on the eastern flanks of Mt. Kinabalu. It is in rugged country with elevation ranging from 1, 300m to 2, 000m. During June-September 1965, the United Nations Labuk Valley Project conducted a geochemical prospecting survey over the eastern flanks of Mt. Kinabalu, and revealed high anomalous copper values in some stream sediments of the Mamut River. Then, they discovered a wide area of disseminated copper sulphide mineralization in the headwaters of a south band tributary (M-2) of the Mamut River.
The prospecting by the Geological Survey of Sabah started in 1966 over the anomalously high copper bearing whole area which included the Mamut watershed. Exploration works which included detailed geological, geophysical survey, and diamond drilling, have been conducted during two years (1968-1969) by the Overseas Mineral Resources Development Company which obtained a license of exploration from the Sabah Government in 1967. The ore deposit of the Mamut-2 mine is a low grade gold-bearing copper deposit belonging to the so-called "Porphyry Copper Deposit". The deposit shows low grade copper disseminations with association of silicification of diorite-porphyrite stocks which intruded Tertiary sedimentary rocks and ultra-basic rocks. The silicification is in the form of stockworks of saccharoidal quartz veinlet, and accompanies sulphides and gold. Pyrite, chalcopyrite and chalcocite form the bulk of the sulphides and are associated with small amount of molybdenite, bornite and green copper minerals.

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Modes of occurrences of ore shoots in each vein of the Akenobe Mine may suggest the direction of flows of ore-forming solutions, which were introduced at the north-east trending faults. A rather remarkable horizontal zonal arrangement of ores has been recognized in the mining area where the zones of Sn-W, Cu, Pb-Zn and Au-Ag ores are arranged from center succesively. In this central portion is an deep Akenobe fault with the north-south strike, which might have intimate relation with a set of the north-east trending. faults. The both sets of faults mentioned above may have been active before and after the mineralization. Recent exploration works have been conducted again in the neighbourhood of the Akenobe fault.

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Since the first discovery of uranium mineralization in the Mesozoic lacustrine. Kwanmon group in 1966, many indications of the uranium deposits had been found in the province of West Chugoku and North Kyushu. This paper mainly presents of the deposits in the Toyota district, Yamaguchi Prefecture, as a typical example of them. The deposits are classified into four types by their modes of occurrence, namely, the dike-type, the fault fracture-type, the sandstone-type and the carbonaceous material-type. The following has been revealed after the geological investigation. (1) The dike-type and fault fracture-type deposits are distributed in a straight line which runs parallel to the Nagato Tectonic Line of NE-SW trend. (2) Most sandstone-type deposits occur within a restricted stratigraphical horizon. (3) The grade of radioactive disequilibrium is closely related with the modes occurrence of the ore. (4) Thuringite in dikes and sandstones plays an important role of concentrating of uranium. (5) Uraninite, pitchblende, autunite, torbernite, uranophane, beta-uranophane and phosphouranylite are identified-in the enriched zones of the deposits.

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The directed laser beam has been proved for more useful for the centering of underground drifting of long galleries, than the conventional surveying method. The apparatus, Nippon Electric Corporations model GLD 2001 using a helium-neon laser beam, was set at a new prospecting crosscut at the mine. This paper describes the method of operation and use of the apparatus in detail.
The main advantages of the apparatus are high labor efficiency and high precision of direction and inclination. The comparative cost of the operation suggests the an inexpensive availability of the apparatus.

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Thd Hirota mine is located approximately 20 kilometers to the south of the Matsuyama City in the Ehime Prefecture.
The geology of this mine is made of the Sanbagawa-crystalline schists and the overlying Tertiary formations of conglomerate and andestic basalt, intrued by andesite and liparite.
The ore deposits are the bedded cupriferous pyritic ore deposits occurring in the green schists and are composed chiefly of pyrite and chalcopyrite with a small amount of pyrrhotite, magnetite, sphalerite and galena.
The mode of occurrence of ore deposits is concordant with the structure of country rocks. The following characteristics of the ore deposits are notable:
1. The horizon of ore deposits is limited within the green schist.
2. Close to the ore deposits, there is hematite-quartz schist beds which form a direct wall rock in some places.
3. Ore shoots are formed in the syncline.
4. Lineations and the folding axes agrees well eack other, suggesting that there is an intimate correlation between the ore shoot and the lineation.
5. The natures of the ore in the deposits are massive, banded and disseminated ores successively from the lower to the upper horizon of the deposits succession remains unchanged over the wide area.
6. Exploration works have been undertaken under the working hypothesis of the syngenetic origin, with good results.

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A number of gold-silver mines on Sado Island, Onomi, Takachi, Kanoura, Kitaebisu, Sado and Tsurushi mines, belong to the type classified as epithermal fissure-filling deposits. These mines are situated on the western slope of the Osado mountain range of the Island.
The Sado mine, the largest gold producer in Japan ever since its opening in ancient age, consists of very many Au-Ag quartz veins which filled fissures in the lower Miocene formations.
Main vein fissures are intimately related to the movement of the second order fractures trending east-west. These fractures are formed by the NE-SW trending master fractures, with a wider mineralized zone by virtue of many branch and parallel veins.
The developments of vein fissures are observed more prominently in brittle rocks such as shale and bedded fine tuff than in the massive pyroclastic rocks and lava flows.
The ore shoots are formed mostly in the lower Aikawa formation surrounding the rhyolite dome which lies in the deeper part of the mine area.
Recent prospecting works based on the re-analysis of structural patterns of the mineralized areas have proved the existence of promising new veins, and this will contribute to the revival of the Sado mine, which has been idle for fifteen years.

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The Konomai-Numanoue district, Hokkaido, Northern Japan, is one of the most important producers of gold and silver, in which so many hydrothermal deposits of Au-Ag bearing quartz veins in Neogenè age have been discovered and developed.
In order to obtain the basic data of primary dispersion of elements due to Au-Ag mineralization, and at the same time, to divide the huge body of the rhyolites in, upper parts of the Konomai formation into some units to understand the geologic structure of the rhyolite body, about 380 specimens of the rhyolites were collected and analyzed spectrochemically.
Following geochemical features of the rhyolites were deduced from the results of the investigation:
(1) The known Au-Ag deposits are surrounded by the halos in which some concentrations of Ag are recognized.
(2) The known Au-Ag deposits are situated in the Na-decreased zones which show the presence of hydrothermal alteration aureoles.
(3) The western part of the rhyolite body, can be devided into three units by the concentration characteristics of basic elements, such as Ni, Cr, Cu, etc.
(4) The known Au-Ag deposits except the Numanoue vein group are in the areas in which the basic elements are relatively concentrated.

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The regional geological survey, which was planned for prospecting the metallic ore deposits in the 27 hopeful districts in Japan, is carried out by the Metallic Minerals Exploration Agency of Japan.
The geophysical exploration methods are employed for this regional geological survey especially in the "Kuroko" type ore deposit areas, to obtain some effective information, the structure of basement rocks and of ore-bearing horizons.
The geophysical exploration methods include gravity, seismic, sonic and other methods, the first of which is the most effective exploration method to get information of the regional geological structures such as faults, folding, doming and/or basin structures. The seismic method is used for obtaining the quantitative information about the depth of basement rocks and/or ore-bearing horizons, and the sonic exploration method is used for obtaining the same information in the near shore area.
The results of gravity and seismic prospecting in the Kita-Shimane district and of sonic prospecting in the Shimoita district are presented in this paper, which are good examples showing effective geophysical exploration methods applied to "Kuroko" deposit areas.

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The portable borer, Model BP3, is a compact and easy-to-handle boring machine to be used for such specific purposes as core boring or pilot boring up to the depth of 30m to 60m.
Since as a conventional air auger was found to be inconvenient when applied to actual operation, they have been, however, overcome by installing such devices as mentioned below, and thus the model BP3 was manufactured.
1. A rod puller was installed for lifting and lowering rods.
2. A hinge base was installed for toppling down the machine in order to shorten the time for rod changing.
3. An auto-feeder was installed for automatic feeding.
4. It was mounted on wagon drill or fan cut rig for boring operations at high roof places.

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In order to increase the recovery efficiency of cores, easiness of enlarging holes and overall work efficiencies, the compressed air-blow method has been applied to the conventional air-blow system, by which were effected also the elimination of slime and the cooling of bits.
Scattering of rock dust was prevented by the specially designed device and dust collector tank. Drill bits were improved for this method by use of the specially designed. crown with the air holes atop and the improved hard metal arrangements.

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Some improvements of drilling machines have been carried out to advance the overall rationalization of the drilling operation, including the mitigation of hard labor, increase of drilling efficiency and the securing underground work safety.
As the first step to the full-automatic control of drilling machines in future, an experiment has been performed successfully with specially designed automatic control equipments in the conventional drilling machines.

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