Strontium isotopic ratios (strontium-87/strontium-86) of five barite samples from five Kuroko-type and vein-type ore deposits in Northeastern Japan and Southwestern Hokkaido were measured mass-spectrometrically. The values obtained are quite uniform, being in the narrow range between 0.7040 and 0.7044±0.0004. These values are extraordinarily low in comparison with the recent data for a number of sulfate minerals from Fukazawa and Kosaka Kuroko-type ore deposits (Farrell et al., 1978).
It is suggested that the strontium isotopic level of Kuroko ore-forming solution might have in some cases lowered down almost exactly to that of Tertiary volcanic rocks depending possibly on the degree of interaction between the ore-forming solution of normal sea water origin and the volcanic rocks (Farrell et al., 1978).

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NaCrSi₂O₆-NaScSi₂O₆ pyroxene solid solutions were synthesized by solid state reaction at 1 atm. There is a miscibility gap between the two end components. Their crystal field spectra were measured and compared with that of NaCrSi₂O₆-CaMgSi₂O₆ pyroxene solid solutions. The relationships between the immiscibility phenomena and the M1-O distance in NaCrSi₂O₆ bearing pyroxene solid solutions were discussed.

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Glaucophane-bearing metagabbros occur in the Iratsu albite-epidote amphibolite mass of the Sanbagawa metamorphic belt in central Shikoku. Typical mineral assemblage of glaucophane-bearing rocks is garnet+omphacite+glaucophane+epidote+subcalcic amphiboles+paragonite+albite. Two stages of equilibration are recognized, the first stage for garnet+omphacite+Fe³⁺-rich epidote and the second stage for glaucophane+subcalcic amphibole+chlorite+Al-rich epidote. The glaucophane in the Iratsu mass has higher content of Na₂Mg₃Al₂Si₈O₂₂(OH)₂ component than any of alkali amphiboles so far known from the Sanbagawa metamorphic belt.

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In the Tsukuba district the strata of metasediments can be classified into the Hirasawa, Tojoji and Yuki-iri Formations in the ascending order of stratigraphic succession based on sedimentary structures. The Hirasawa Formation, over 1500m in thickness, consists largely of a very thin alternation of mudstone and siltstone or sandstone (from 0.3 to 1cm thick). The Tojoji Formation, from 300 to 600m in thickness, is mainly composed of an alternation of relatively thick mudstone and siltstone or sandstone (from 10 to 50cm thick) together with subordinate massive sandstone beds. The Yuki-iri Formation, over 600m in thickness, consists mostly of a thin alternation of mudstone and siltstone or sandstone (from 1 to 3cm thick), though it contains some massive mudstone layers.
The metamorphic terrane is divided into three zones, A, B and C, in the order of increasing metamorphic grade on the basis of mineral parageneses in pelites and psammites. The characteristic mineral assemblages of the three zones as follows.
Zone A: Muscovite+plagioclase ± orthoclase ± andalusite.
Zone B: Fibrolite+muscovite+orthoclase+plagioclase+±cordierite.
Zone C: Fibrolite+orthoclase+plagioclase+cordierite ± pyralspite. Biotite, quartz and graphite are always present in any of these assemblages.
The geological and petrological facts indicate that the thermal structure of this district is discordant with stratigraphic horizon. The distribution of metamorphic temperature, however, seems to be dependent on the shape of biotite granite mass. It can be explained by the idea that these metamorphites were subjected to contact metamorphism in the amphibolite facies by the biotite granite intrusion. The results of K-Ar dating (Shiba et al., 1979) support this explanation.
The tectonic movement in this district might have begun after later Jurassic and continued to early Tertiary time.

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