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Volume 72, Issue 5
Displaying 1-4 of 4 articles from this issue
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Tsuyoshi Maki, Naruhiko Kashima1977 Volume 72 Issue 5 Pages 181-187
Published: May 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSSome cave phosphate minerals, three brushite, four hydroxyapatite, three taranakite, two variscite and one aluminium phosphate mineral from limestone caves in Japan and lava cave in Korea, were analyzed chemically.
The chemical compositions are shown in Table 3-7 with previous data and standardized data.View full abstractDownload PDF (229K) -
Hisahide Honma1977 Volume 72 Issue 5 Pages 188-194
Published: May 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe interstratified sericite-montmorillonite was recognized at one of some dolerite dykes penetrating into the “siliceous ore” at the Yunosawa deposits, Furutobe Kuroko mine, Akita Prefecture.
The clay mineral is estimated as 70-80% sericite and 30-20% montmorillonite by means of X-ray method. But, the clay minerals occurred in the “siliceous ore” in the vicinity of the dyke are hydro-mica and interstratified sericite-montmorillonite of sericite dominant.
On the other hand, the interstratified sericite-montmorillonite occurred in the dolerite is interpreted as secondary altered products of chlorite (or amorphous materials of chlorite compositions) which were primary altered products of the dolerite on the basis of the experimental results and the mode of occurrence of the dyke.View full abstractDownload PDF (271K) -
JUJIN SUZUKI, MASAHIRO ITO, KAZUHIRO SUZUKI, YOSHIRO TSUZUKI1977 Volume 72 Issue 5 Pages 195-204
Published: May 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSNickel- and chromium-bearing clay minerals occur in quartz-magnesite rock which is an alteration product of serpentinite in the Sambagawa metamorphic terrane at Izumma, Shizuoka Prefecture.
They are classified into two varieties on the basis of their mineralogical properties:
Variety A occurs as aggregates each about 50μm long and up to 20μm wide in pore spaces between quartz grains of the quartz-magnesite rock. The aggregates consisting of very fine-grained crystals are rich in Cr2O3 and NiO. Of considerable interest is the fact that the contents of Cr2O3 and NiO vary from aggregate to aggregate (4.18-7.40% Cr2O3 and 3.28-27.9% NiO). Judging from the experimental results, this variety is considered to be smectite with abundant potassium in its interlayer positions.
Variety B occurs as infillings in small fissures existing especially in the marginal part of the quartz-magnesite rock. The material is poor in Cr2O3 and NiO contents (0.05-0.35% Cr2O3 and 0.05-0.44% NiO) and is considerably homogeneous. This variety is considered to be a smectite with a basal reflection at 11 Å which splits with ethylene glycol probably suggesting a mixed-layer structure.
Variety A is considered to have been produced by the action of a chromium- and nickel-rich hydrothermal solution trapped in minor pore spaces between quartz grains of the quartz-magnesite rock, while Variety B, which is poorer in chromium and nickel than Variety A, was produced from a mobile hydrothermal solution with smaller amounts of chromium and nickel. There is a possibility that the development of the latter variety is intimately related to a lower temperature of water during secondary alteration processes.View full abstractDownload PDF (2836K) -
MASAO ASAMI1977 Volume 72 Issue 5 Pages 205-220
Published: May 05, 1977
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSMany localities of staurolite-bearing schists have been found in a lower grade part of the sillimanite zone in the Hazu area, the Ryoke metamorphic belt in central Japan. Two modes of occurrence of staurolite have been recognized in this area.
(A) Staurolite in a relic form armored with porphyroblastic andalusite, which is found in mica schists and quartz schists. The andalusite occurs in a matrix composed of quartz, biotite, muscovite, sillimanite, garnet, plagioclase, ilmenite and graphite. This is the prevailing mode of occurrence in this area.
(B) Staurolite is coexisting with quartz, biotite, garnet, sillimanite, plagioclase, andalusite, ilmenite and graphite, but with no muscovite. This is rarely found only in quartz schists.
It is notable that the mineral assemblage observed in porphyroblastic andalusite in which staurolite of the mode (A) occurs is similar to that of the quartz schist with staurolite of the mode (B). Three staurolite-bearing schists and three sillimanite-andalusite schists with no staurolite were chemically analyzed. There have not been found any significant difference in chemical composition among them, except for the K-value in the AKF ratio.
On the basis of petrography and chemistry of the staurolite-bearing schists, it is concluded that staurolite of the mode (A) may be an armored relic after the metamorphic reaction of staurolite with muscovite, and that it as well as staurolite of the mode (B) seem to be stable under physical conditions in the lower grade part of the sillimanite zone in this area. The Ryoke metamorphism in the Hazu area is considered to be of higher PH2O conditions than those in the other areas in the Ryoke belt.View full abstractDownload PDF (1732K)
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