It is customary to neutralize the acidic mineral contamination of mine water by alkaline material such as powdered CaCO₃ in sulphur mines. The author found a simple and non-expensive process whose installation in the Matsuo Sulphur mine accomplished the objective with satisfaction. The process consisted of using the purifying media of the soil-rock system such as ion-exchange, adsorption, neutralization, and filtration. The acidic mineral-contaminated water was poured into the earth through bore holes and such and the purified water was assimilated with the uncontaminated water flowing underground.
In order to execute the process, the following considerations were made:
(a) The stratum which has a great purifying power is composed of porous layers, such as a younger sedimentary layer (fan deposit, detritus and younger volcanic tuff, etc.) and not of compact layers such as igneous rocks and Mesozoic or Paleozoic sedimentary rocks. Furthermore, the ground-water layer which is to receive the mineral water must possess a free water table which is beneath the earth's surface. Accordingly, it is necessary to seek a territory which has these qualifications.
(b) The area along the river near the sulphur mine is generally already contaminated to some extent, the pH being as low as 3.0. In order to avoid enlarging the contaminated ared, it is necessary that the installation positions of the instillment bore holes are located in this already contaminated area, and not in the noncontaminated stream district.
(c) The purification power of the soil-rock system in general decreases gradually with the increase of the instillment. However, depending upon the texture of the soil-rock system, it is possible that a rapid loss of the power can occur. For such an eventuality, it is necessary to pour the contaminated mineral water into a new area. Consequently, it is necessary to be able to shift at will.
(d) Since the loss of the purification power of the soil-rock. system is liable to introduce a momentous effect at down-stream territory by exposing the injected acidic water at the earth's surface, it is of utmost importancee to perceive and control the underground condition sufficiently at the instillment territory. It follows that the selection of the territory should be made so as to afford reliability and facility of the control operation.
The installation was commenced in July of 1952. A brief description follows.

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In the previous papers, the authors reported the formation temperatures of some deposits by decrepitation method.
In order to examine into the results, they designed the heating stage attached to a microscope and measured the vacuole filling temperatures by observing the disappearance of gas bubbles in liquid inclusions.
The filling temperatures of 50 vacuoles thin sections of a sample of quartz aggregate from the Hosokura mine (specimen no. Hosokura 395) range from 184°C to 217°C and average about 200°C. Most of the filling temperatures are concentrated between 197°C-208°C. Those of 20 vacuoles of the quartz aggregate from the Rendaiji mine (specimen no. Rendaiji A-1-3) range from 190°C to 225°C and average 208°C. Most of the filling temperatures are concentrated between 201°C-210°C. The cause of the discrepancy of filling temperature of ±15°C in a sample is unknown.
In the previous experiment, decrepitation temperature of the quartz (Hosokura 395) was determined to be 210°C, which almost coincides with the filling temperature by the heating stage method. Also, decrepitation temperature of the quartz (Rendaiji A-1-3) was determined to be 260°C which does not coincide with filling temperature by the heating stage method. The discrepancy in the specimen (Rendaiji A-1-3) would be due to the incompleteness of the counting apparatus and the misinterpretation of the decrepigraph shown in Fig.8. If one regards 210°C as the decrepitation temperature in this decrepigraph, it coincides with the temperature determined by the heating stage method.
Also, the authors are studying another method of determination of formation temperature of minerals, using a heating stage with "Ultropak" lens, whereby the temperature at which the immersed liquid begins to bubble will be determined.

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For the purpose of explaining and interpreting the geologic structure in country rocks of "Kieslager", the writer has thought out a new method to analyse the fabric ("L-S fabric") inwoven by lineation (L) and schistosity plane (S) of the rocks. At this analysis, both lineation and schistosity plane have been plotted as a point on a stereographic projection. Because every lineation may lie on the respective schistosity plane, a plotted point of the lineation (L) must be placed on the great circle drawn 90°from another plotted point of the schistosity plane (S). Also in the "L-S fabric diagram" contoured statistically, max. L and max. S show the similar relationship.
In the diagram of country rocks which show "Beule" due to the shape of ore-body, the figure of L and S may be deformed nearly along the great circle on which the max. L and S are placed. By the manner of this deformation of the figure, the direction in which the ore-body grows either thin or thick, can be determined.
In the other kinds of deposits except "Kieslager", the "F fabric" —the small fault (slip) system along the ore-body or the fracture (joint) system controled the shape of ore-body— shows the deformation of "Beule" instead of the "L-S fabric". Also from the manner of this "Beule" deformation in the "F fabric diagram (F. F. D.)", the variation in thickness of the ore-body can be determined.

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The writer has studied the genesis of the Matsuo sulphur deposits since 1952. In this paper the geology of the mine will be described. Conclusions are briefly summarized as follows.
(1) The district is composed of, going from the lower to the upper, Kitamatagawa formation, Kurosawa formation, Hachimantai formation (the country rock of the deposits), Akagawa lava and agglomerate, Ishiyama lava, Daikokumori agglomerate, Onagane lower and upper lavas, Chausudake lava, Maemoriyama lava and some terrace and alluvial deposits. The Kitamatagawa formation seems to be correlated with the Hashiba formation, which is upper Miocene or lower Pleistocene in age. The ages of the Kurosawa and the Hachimantai formations are still unknown. The rocks overlying these formations are very probably products of Pleistocene volcanic activity. The geological map and columnar section are shown in Fig. 1 and 2.
(2) Except for the basal rocks and the cone-shaped volcanic products, the main part of above-mentioned rock series dip gently toward the east. The semi-lunar low hills of Ishiyame and Kamota seem to have been formed by step faults, and the swampy zones embraced by them are probably due to the presence of underlying soft rocks formed by post-volcanic alteration.
(3) The succession of igneous products in this area is as follows: acidic dacite (Kitamatagawa formation)→more or less basic dacite with quartz-bearing andesite and two-pyroxene andesite (Kurosawa formation)→two-pyroxene andesite (Hachimantai formation, Akagawa and Ishiyama lava)→olivine-bearing two-pyroxene andesite (Daikokumori agglomerate, Onagane, Chausudake and Maemoriyama lava).
(4) After the great eruption of the two-pyroxene andesite, the sulphur and iron-sulphide mineralization took place and continued to the early stage of volcanic activity of the olivine-bearing two-pyroxene andesite.

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The coal-bearing formations of Joban Coal-field are the heteropic facies of the correlative marine formations. The Palaeogene marine transgression of this coal-field shows Grabau's regular transgressive overlapping. The coal-bearing formations of the Kido, Tomioka areas, northern part of Futaba district are considered synchronous with the marine Asagai formation. The cyclothem of the coal-bearing bed is the smallest periodic transgressive unit. The coal seam taken as a whole indicates a layer of the last and stable conditions in which a coal swamp was formed through a relative long time.

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