Almost perfect correspondence in textures and chemical compositions of the fine grained "emery" of stratiform deposit in the upper Palaeozoic-lower Mesozoic formation, at Shinkiura mine, Oita Prefecture, Kyushu, Japan, to some lateritic red shales or bauxites were recently found by the present author.
The textures retained in the "emery" ores are either pisolitic or concretional. Those of deformed or reworked fragmental pisolites are also preserved. The "emery" ores are heterogeneous in composition and comprise corundum, andalusite, cordierite, hercynite, ironoxides, biotite, amphibole and tourmaline, assuming apparently complicated mineral assemblages. But, in the basis, the mineral paragenesis is represented by either of the two tetrahedra; andalusite-cordierite-spinel-magnetite-silica rich domain, and corundum-andalusite-spinel-magnetite-silica poor. domain on SiO₂-(FeO+MgO)-Fe₂O₃, -AL₂O₃, diagram. In chemical composition, compared with the lateritic shales, the trend of dehydration and reduction is evident. All these petrographic features of the "emery" ores of Shinkiura mine might be interpreted as the result of thermal metamorphism of some lateritic shales in the sedimentary formation mentioned above. The cause of this metamorphism is attributed to the Tertiary granitic intrution to the south.
A new subject on palaeogeography of the upper Palaeozoic-lower Mesozoic age in this region with related to the presumed occurrence of the lateritic shales in the formation is open to future research.

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The tungsten deposits of the Ohtani and Kaneuchi mines belong to the hypothermal or pegmatitic vein-type. These deposits are genetically related to the late Cretaceous or early Tertiary granitic activities. In the adjacent areas to these mines, the same granitic .activities are also related to the deposits of the Ikuno, Akenobe and Tada mines, belonging to xenothermal type. The granitic activities and mineralizations in these districts would happen during 40×106 years ranging from Cretaceous to Tertiary Periods.
The ore deposit of the Ohtani mine filling the tension cracks and wrench faults occurs in the granodiorite stock intruded into the core part of the anticline of the folded Paleozoic formation. The vein fissures were formed by the lateral pressure causing the regional-scale folded structure accompanied by the upheaval pressure of the granitic magma. The ore deposit of the Kaneuchi mine exists in the hornfelsic rocks forming the dome structure due to the upheaval of the granitic cryptobatholith. The vein fissures of the Kaneuchi mine were also formed by the regional-scale folded structure accompanied by upheaval pressure due to the doming up of the cryptobatholith. These pressures correspond to two principal stresses, i, e., maximum principal stress (σ₁) and intermediate principal stress (σ₂). The leading vein fissures belong to the tension crack perpendicular to the boundary plane between the cryptobatholith of the granite and the surrounding Paleozoic formation. The tension cracks include the directions of the maximum and intermediate principal stresses, i. e., two kinds of pressure described above. Namely they are perpendicular to the minimum principal stress (σ₃). These fissures of both deposits were mineralized by the underlying granitic magma which would be perhaps rich in fluid containing high contents of salts.
The ore minerals of both deposits are scheelite, wolframite, cassiterite, chalcopyrite, cubanite, pyrrhotite, stannite, sphalerite, mackinawite and others in accessory amounts, accompanied by quartz, muscovite, tourmaline, fluorite, etc. In the Ohtani mine, the exsolution texture of cubanite, chalcopyrite, pyrrhotite and mackinawite are observed under the microscope.
Though the country rock of the Ohtani mine is granodiorite, the tungsten mineral in this deposit is only scheelite. The source of the ore-forming fluid in this area would exist in the deeper part underneath the present country rock, i, e., granodiorite which would be formed by the contamination of the granitic magma with the calcareous rock at the time of intrusion. Scheelite would be formed by the effect of the calcareous rock through which the ore-forming fluid flowed upwards. This fact has the relation with the problem of fluid inclusion in the constituents quartz of the granodiorite discussed in the other paper.
In the Kaneuchi mine, the zonal distribution of ore minerals is recognized according to the distance from the cryptobatholith of the granite, which reflects the decrepitation temperatures discussed in the other paper.
It is noticed in these districts that in the hypothermal tungsten and tin veins primary bornite, primary chalcocite, mawsonite and stannoidite are lacking, which are found in the xenothermal tin and tungsten veins. While, cubanite, pyrrhotite, and mackinawite are not recognized in the xenothermal type, which exist in the hypothermal type.

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Volcanic glass inclusions in the quartz phenocrysts of rhyolite and in the quartz grains of rhyolitic tuff from the Chitose gold-silver mine, Hokkaido, were studied by means of the microscopic observation, heating experiments, electron-probe microanalysis and laserprobe microanalysis. The glass inclusions in the rhyolite generally consist of transparent glass and a bubble, and some of them contain dendritic crystals. On the other hand, the glass inclusions in the tuff contain reddish brown hexagonal tabular crystals, short prismatic crystals, long prismatic or acicular crystals. The heating experiments revealed that the homogenization temperature of the glass inclusions in rhyolite was in the range between 1, 000°C and 1, 200°C, while that of tuff was in the range of 870°-1, 000°C.
The major compositions of glass inclusions in rhyolite and tuff were determined by the electron-probe microanalysis as follows; SiO₂:70-76wt.%, AL₂O23:±12wt.%, Na₂O:2-5wt.%, K₂O:2-4wt.%, CaO:±1wt.%, MgO:<0.2wt.%, FeO(total):±0.8wt.%. No distinct difference was recognized between the glass inclusion of rhyolite and that of tuff. The laser-probe microanalysis showed the presence of Cu, Ag, Ti and Zn in the glass inclusions.
Though the present data are not enough to extract the general conclusion on the formation of glass inclusions in volcanic rocks, it is presumed from the microscopic observation and heating experiments that glass inclusions would inform us of the approximate thermal history. This presumed history, however, would give us merely a general trend, because the phase changes such as the melting, nucleation and growth of crystals in glass inclusions occur metastably in various degrees. The devitrification of glass inclusions does not necessarily mean a slow cooling, because the hydrothermal actions would also cause the devitrification. Larger inclusions are more frequently devitrified than smaller inclusions.

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Clay minerals showing a zonal distribution in and around several Kuroko deposits in the Hokuroku district, Akita Prefecture, are outlined together with some investigations on x-ray patterns of sericite minerals.
The ore deposits of the Shakanai, Hanaoka (Matsumine), Kosaka (Uchinotai and Uwamuki), and Furutobe mines, on which the present study has been made, belong to typical Kuroko deposits occurring in altered felsic volcanics of Miocene age, and consist successively of silicified rhyolite and pyroclastic rocks, gypsum ore zone, siliceous ore (or pyrite ore) zone, yellow ore zone, black ore zone, ferruginous chert in ascending order. Intensely argillized rock which is mostly derived from tuff is distributed within and surrounding the ore deposits.
The clay mineral occurring most abundantly in the alteration zone is sericite minerals, which are fine-grained and often form monomineralic clays. Sometimes they are associated closely with sulfide minerals in the ore deposits. X-ray diffraction analysis has revealed that they are interstratified minerals of sericite-montmorillonite as well as sericite. The interstratified minerals usually contain only small amounts of expandable layers and show subtle variations of basal reflections, but occasionally contain up to 40 per cent expandable layers and have long spacing (25Å or longer) basal reflections. The variations of basal reflections were investigated in relation to their modes of occurrence by measurements of peak widths at the half height of about 10Å and 5Å reflections (ω₁ and ω₂) and of the peak positions of 10-12Å reflection. The results indicate that those associated with the silicified rocks and the siliceous ore are sericite or interstratified sericite-montmorillonite containing very small amounts of expandable layers, and that most from the other portions of the deposits are interstratified sericite-montmorillonite with a trend of having more expand-able layers in the upper or outer portions of the deposits. The polytypes of sericite minerals are 2M₁, 1M, and 1Md, the last of which is found only in the interstratified minerals.
Mg-chlorite is secondly widespread, particularly being associated with the gypsum ore. The chlorites associated with the ferruginous chert and in the altered pyroclastic rocks distant from the ore deposits are usually ferromagnesian.
In addition to these minerals, following various clay minerals are found locally in the alteration zones: interstratified Mg-chlorite-saponite, sudoite, interstratified sudoite-mont-morillonite, interstratified sericite-sudoite, montmorillonite, nacrite, dickite, kaolinite, and pyrophyllite. The fact that the clay minerals distribute zonally with a close relation to the ore deposits may indicate their origin to be connected directly to the mineralization of metal ores, and may suggest primary formation of the interstratified sericite-montmorillonite.

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