236 



B. KOTO. 



he made as to the orujin of the pegmatitic stnieture being primary or 

 secondary. 



c) Sehistose Amphihole-Granite. 



This modification may be readily recognized as such even on a 

 cursory examination of hand-specimens, and no confounding with tlie 

 normal granite is likely to occur. It is of a coarse, granulo-lamellar 

 (faserig) structure, and generally of a rather darker shade than the 

 primary rock. The schistosity is imperfectly developed ; consequently 

 the cleaved surface is exceedingly rough, irregular, and notched. A 

 typical rock belonging to this class is well exposed along the steep 

 ascent of the Kawachi togé (Kawachi pass), between the town of 

 Tomioka and the village of Kawachi, and is also found near to the iron 

 deposit of Chûka, Naraha göri. This is really what Mr. Kochibe 

 calls the "7/ca^'/ gneiss." All microscopically visible components are 

 now crushed into deformed bodies ; the hitherto even-lamellar bi(jtite 

 is altered into flexuous and wrinkled lamelltB ; the hornblende is no 

 lono-er of a prismatic form ; the quartz and hornblande are rolled out 

 and o'rained, and com[)acted into one mass with a feldspar centre zoned 

 by the grains of quartz, well seen on a weathered surface on account (jf 

 the different degrees of pel lucidity of the two minerals. 



Examining with the microscope, the structure becomes more 

 apparent. Originally fresh minerals have acquired a dirty aspect and 

 become variously fissured. In the first place the biotite is for the 

 most part bleached, and its chloritic bands are interposed between 

 lio-ht-brown lamellœ. 'No trace of its original outlines is ])reserved. 

 A chloritic, fibrous substance often creeps al(jng the adjoining faces 

 and fissures of the compact biotite, and the fibrous mass is connected by 

 strino's from the mother-mineral, either hornblende or biotite. The horn- 

 blende has met the same fate ; its margins are irregular and frayed, 



