In the lavas of Kayodake, Komagatake and Iwate volcanic groups of the Nasu volcanic zone in the north-eastern Japan, there are many basalts and basic andesites which contain much large plagioclase phenocrysts (up to 2cm.) of anorthitic composition (An 95). Particularly the lowest lava of the Kayodake volcanic group contains plagioclase phenocrysts more than 43 per cent in volume; therefore its A1₂0₃ and CaO contents attain to 23.74 and 12.34 per cent, respectively. Its chemical composition resembles to that of anorthositic gabbro or kenningite.
Regarding to the A1₂0₃, this is probably highest value ever reported in the world in the effusive form. It is considered that the origin of such lavas of abnormal composition should be attributed to the floating up of anorthite crystals and to the sinking down of olivine and pyroxene crystals formed in the early stage.

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On the magnetite and the hematite from the cupriferous iron sulphide deposits, such as the Shingü, Shirataki, Sazare, and Kõtsu mines, occurring in the Sambagawa crystalline schist zone, the writer has chiefly investigated occurrence, various textures under the ore-microscope distribution of minor elements and magnetic property.
It is the purpose of this paper to give some interpretation on the genesis of Kieslager.

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The paragenesis of ludwigite has been frequently described by Geijer, Watanabe, Tilley and others, however, that of paigeite has not been described in detail. The present paper purports to describe the paragenesis of paigeite from the Kamaishi mine, Iwate Pref., Japan, and to clarify the difference in the paragenesis of paigeite and ludwigite, moreover, to discuss their genesis.
Assuming a similarity of temperature and pressure during the formation of paragenesis of paigeite and ludwigite, and that chemical potentials of H₂O, CO₂, Na₂O, K₂O, B₂O₃ in the pore fluids participating in the formation of these parageneses were alike, and further that changes in the chemical potential of Fe had no effect on the composition of diopside, forsterite, phlogopite, spinel and tourmaline, but that, they it may be had a striking effect on the composition of the mineral of ludwigite series, concluded that the paragenesis of paigeite was formed in a condition where the chemical potential of O₂ in the pore fluids was low and that of Fe in the system was high, whereas, the paragenesis of ludwigite was formed in a condition where the chemical potential of O₂ was high and that of Fe was low.

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Petrologic and sedimentalogic studies on the source-rocks of petroleum in the Teradomari folding zone in Niigata Prefecture have been carried out. The extractive organic constituents of the fine grained clastics, so-called grey shale, black shale and hard shale, were determined. The relation ships between the stratigraphic distribution of the organic constituents and the lithologic features and other characteristics of the source rocks themselves were discussed in the present paper.
It may be suggested that the results afford important criteria for the interpretation of complex phenomena related with the Neogene sediments developed in the oil-fields of Japan.

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This paper deals with the proposal of a new hypothesis for inflammable natural gas pools of special type found theoretically by the writer in 1948 and has been studied in succession. The hypothesis for the special gas pools is characterized essentially by inflamable natural gas dissolved in the underground water with saturate solubility without oil. The saturate degree is generally determined by the physical and chemical conditions of the solvent water under the ground. The reservoir pressure and temperature are the main factors which control the solubility of inflammable natural gas for the undergound water.
Many productive gas wells for the gas pools of this type have already successfully drilled and now under drilling in many areas in Japan from Hokkaidõ to Kyüshü, especially vividful in Niigata plain and Southern Kantõ basin. The gas pools of this type are important for our country because more than 80% of total inflammable natural gas production of Japan is occupied by the gas of this type. Many theoritical results have been obtained by us by the observation of these gas fields during last eleven years from 1948 to 1959. These theories derived out of hypothesis proposed here seem not only true, but has no contradiction among many theoritical explanations of the gas field phenomena each other on the point of geological and geophysical views.
As the examples of derived theories from the new hypothesis, this paper also takes up some themes and their outlines.
These themes are shown as follows; (1) vertical disolved gas distribution in the pore water of all strata in the gas field, (2) the gas contents in the inflammable natural gas pools dissolved-in-water type, (3) geochemical prospecting of gas fields, (4) syncline theory for inflammable natural gas pools dissolved-in-water type, (5) arc type exploitation method, (6) calculation of self flowing power for the flowing gas wells, (7) enrichment of inflammable natural gas pools dissolved-in-water type, (8) calculation of gas reserves, (9) stability of natural gas production, (10) generation of gas pools with abnormally high gas-water ratio.
As a result, many theories derived from the same one hypothesis have given us nearly enough explanations for many phenomena on these gas pools and have no contradiction among these explanations each other.
Therefore this basemental hypothesis “the natural gas in the gas pools with under ground water exists in the underground water with dissolved feature” can be considered as the one of the new believable theory.

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