The Shinobu Sulphur Mine is located on the eastern slope of Azuma-volcanoes, in the northwestern part of the Fukushima Basin. The deposits were formed by volcanic activity of diluvial age. They consist of a so-called sedimentary deposit. of a crater-lake and impregnation and metasomatic deposits.
It is difficult to locate the out-crops of these deposits, for they lie between lava-flows and tuff beds. Discovery of new ore-deposits is. most important work now that the mining of the-old ore deposits is almost coming to an end. The object of research presented here was to dis cover new ore bodies.
For this purpose, probable positions of new ore deposits was presumed by use of geological structural data. The location chosen was investigated by the electrical resistivity method.
Upon completion of measurments, resistivity anomalies were recognized at four points.
The author then made a lateral investigation at constant depth (a=20m). In this manner three probable ore deposits were found.
In the author's opinion the electrical resistivity method is the most useful one for sulphur ore deposits which usually are buried under the ground.

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The silica rock in Beppu mine is an replacement alteration product of the hornblende andesite by epithermal solutions.
The high grade ore is chiefly composed of opaline silica while low grade, ore contains alunite, kaolinite, limonite, hematite, sulphur, rutile and iron sulphide.
The mother rock alteration of Beppu mine is characterized by a zonal arrangement from the surface to downward as follows : silica rock, alunite clay, kaolinite clay, and original rock.
The chemical composition of the high grade ore is as follows:
SiO₂ AL₂O₃ Fe₂O₃+FeO CaO MgO K₂O Na₂O Ig. loss Total
90.00 1.82 0.20 0.40 tr. tr. tr. 7.95 100.37
The ore forming agent may have been an ascending hydrothermal sulphuric solution of vol canic origin.

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Almost all of the cupriferous pyritic bedded deposits in phyllitic rocks show échelon structures in small or in large scale. The writer investigated these structures and recognized that all unit bodies which constitute one deposit always slightly cut the fissility of the wall rock in a common direction, although they are apparently conformable to the wall rock. In general, all of the échelon structures are found repeatedly along the same horizon of the phyllitic wall rock. The échelon structures are classified into two types, (a) the pitch echelon and (b) the line échelon.
The writer concludes that the deposits are fissure fillings. The results of this study may be applied in prospecting for deposits of this type.

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Ninety six specimens from the Kamioka mine, Obira mine, et al. were heated to approximately 600°C.The decrepitation itation was analyzed electronically and recorded after F. G. Smith's method.
The Kamioka deposit is a pyrometasomatic type, in which skarn minerals such as hedenbergite, etc. are developed with zincblende, galena, etc. From decrepigraphs, we conclude that the formation, temperature of this deposit is 375°-230°C.(corrected for pressure). In part, the temperatures do not reflect the order of deposition, though, in general, the temperatures decline progressively during deposition. Namely, there are some fluctuations of temperature in the successive order of deposition.
In the Obira mine two types of veins are present, i.e. cassiterite-tourmaline-quartz vein and chalcopyrite-arsenopyrite-stannite-quartz vein. In thenorthern part of the mine, both types of the veins are parallel and strike N 45°-50°E dipping 70°-80°to the west. In the southern part they intersect each other to become one vein. From the observation in the adit, the former is of earlier deposition than the latter. Decrepigraphs indicate that the formation temperatures of this deposit is 390°-250°C. (corrected for pressure). The formation temperatures of the two types of veins are nearly the same, though the cassiterite-tourmaline-quartz vein is a little higher than chalcopyrite-arsenopyrite-stannite-qtartz vein. The decrepitation of a quartz crystal found in a vug in the cassiterite-toumaline-quartz vein was determined to be 251°C. This quartz would represent the latest stage of deposition. The deposition temperature of marcasite belonging to the latest stage of the chalcopyrite-arsenopyrite-stannite-quartz vein is 279°C. This temperature is higher, compared with that of the epithermal deposit. Acidity rather than temperature would be the essential condition for deposition of marcasite.
Formation temperature of quartz from the Hosokura mine is 221°C.(corrected for pressure), that of rhodochrosite from the Yagumo mine is 242°C.(corrected for pressure). Both deposits belong to the epithermal type.

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In Hokkaido, there are many ultra-mafic igneous bodies along the two parallel tectonic zones which are named the Kamuikotan zone and the Hidaka zone respectively. These tectonic zones composing the geological back-bone of the island, are regarded as the product of Cretaceous orogenic movement which is called the "Hidaka Orogeny". It is believed that Hidaka zone has an orogenic deep core and the Kamuikotan zone is its westward overthrusting zone. Many characteristics of the ultra-mafic igneous rocks are common to both the tectonic zones. But contrasting features have also been observed in them. One of the most disparate features is that the ultra-mafic rocks of the Kamuikotan zone are almost wholly serpentinized, whereas they are always in the unaltered peridotitic state in the Hidaka zone.
It is in the southern part of the great serpentinite belt in the Kamuikotan zone which has long been well-known as a chromite field that the occurrence of lode ore of chromite has been reported.
The Nittoh mine is situated in the southern part of this chromite field.
The geology of the mining district is very complicated, having irregular dome or basin structure of the sedimentary rocks that are belived to be Pre-Cretaceous in age.
From the modes of occurrences, almost all of the chromite deposits are regarded to be deformed secondarily. The deformation is closely related to the secondary structure of the serpentinite, which is regarded to have been caused by the successive movements of the Hidaka orogeny. The serpentinite having primary structure is massive, and retains the characteristic texture of peridotite, even when the olivine is completely altered to serpentine. On the other hand, the deformed serpentinite is in many places foliated.
The primary form of the chromite deposits in the mining area, is plate-like, and is controlled by the joint system of the massive serpentinite. The secondary structures of the deposits are controlled by the block movement of the massive serpentinite or folding of the foliated serpentinites.
In the Nittoh mine, two types of deformation of the chromite deposit are observed.
In this paper, the writers describe the structural characters of each ore mass with special reference to their relations to the intrusive tectonics of the chromite deposits.
Further studies, especially concerning the properties of ores will be published in the near future.

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During the past few years, remarkable progress has been made in the results of geological survey and exploration works conducted at metal mines in Japan. This has been the outcome of the reform that has taken place in recent years in the attitude towards geological survey through the promotion of such aggressive and desirable measures as are conducive towards progress, namely, the practical application of fundamental theories to the techniques of geological survey and exploration, the propagation of mining geology, and the advancement and widespread use of geo-physical and geo-chemical methods of exploration and diamond drilling.
In the past year 1951, the average amount of newly proven reserves for every meter of exploratory drilling done at the major mines in Japan, more than doubled that of the previous year, while the new reserves developed in the year reached as high as 7 times the amount of ore mined. This indicates a bright future for mine operators. However if we look at this from the aspect of individual mines, the geological surveys conducted at such mines as Konomai, Matsuo, Kamaishi, Ashio, Kune and Yanahara have shown remarkable results but on the other hand some of the large mines have as a result of these surveys indicated a downward trend.
During the year 1951, of the newly developed ore reserves in the 76 major mines of Japan producing various minerals, only 21% of the totally discovered reserves was from virgin deposits, the rest were all associated with already known deposits and have been discovered either below the known ore bodies or in drift heads.
In Japan, it is not only common in the so-called black ores, but there are many instances of blind veins. We must increase the present low ratio of developed ore reserves coming under the category of newly discovered bodies through our efforts in searching for unexplored resources by re-examining the known ore deposits and thereby catching blind deposits in virgin areas.

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Discusses the origin of the coal, and reviews statistical data on the coal reserves of Japan and the world.

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Gives statistical reviews of the geophysical prospecting carried out in Japan during the period of 1946-1951.

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History and present conditions of mineral development in Asia are considered in relation to political influences of European and American powerful countries, and some suggestions are proposed for mineral preservation.

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