Metallogen y of the Japanese Islands. 13 



into the form of beds, at the same time causing regional meta- 

 moi'i^hism of the country rocks. After such a geological change, 

 a fissure was formed along the middle line of the bed, and the 

 side-rock masses slipped down, producing the sliear zone on the 

 exterior part of the bed. Finally, a secondary enrichment took 

 place around the faulted rocks, filling up the interspaces of the 

 fissure. Thus the rock fragments in the beds are rounded or 

 indented on their exterior by the dissolving action of the vadose 

 water. This explanation will, I think, solve the varied structures 

 of the pyrite beds in a very natural way. S. Ishikawa,^^ a Mining 

 Inspector, enumerates 59 copper mines of this species in Japan, 

 namely, 27 in crystalline schists, and 32 in the Paleozoic 

 formation. 



Quite recently very interesting gold deposits have been dis- 

 covered in central Kijûslm, which, upon investigation, seem to l)e 

 an isolated block from the Besshi Province. The region is billy 

 Avith an altitude of about 400 to 2000 ft. above sea level, and is 

 geologically composed of a thick complex of amphibolite and 

 phyllite belonging to the Lower Paleozoic. The amphibolite 

 is a pale green homogeneous rock. The phyllite is a highly 

 contorted lamellar rock, gray to black in colour, showing pearly 

 luster by the presence of the abundant quantity of mica. The 

 latter rock sometimes contains very conspicuous cubic phenocrysts 

 of pyrite, which measure up to 0.5 cm. in diameter, and is usually 

 converted into limonite pseudomorph. Examined under the 

 microscope, the amphibolite consists of elongated green crystals of 

 amphibole and greenish -yellow grains of epidote, cemented by a 

 transparent quartz matrix. Phyllite shows beautiful contortion, 

 microscopically as well as macroscopically, forming alternate layers 

 of quartz, mica and graphite. It is a very noticeable feature that, 

 so much gold exists throughout the rocks for several miles, that 

 sometimes the}^ practically become gold ore themselves. Now, it is 

 a question whether the gold is a primary constituent of rocks, or it 

 had been carried into them at the time of the formation of quartz 



1) Isbikawa: " Geology and Ore-deposits of Oshima." Jour. Gcogr. Soc. Tohyo, Xo. 260, 

 1910 (Japanese). 



