ON THE SO-CALLED CTvYSTALLTNE SCHISTS OF CHICHIBU. 101 



so-called isomorphic shell and the parallel growth do not difter 

 from each oilier but really mean the same thing. 



As to quantity, tom'maline is so abundant that it may be 

 regarded as an essential component. 



The quartz, sericite, garnet, the light-green epidote crystals nnd 

 grains, and lastly, the calcite present no peculiarities worthy of special 

 description. 



The structural modification of the rock varies within a wide range 

 from a coarse-lamellar rock to a thin-tabular graphite- slate ; in the latter 

 the nodules are scarcely visible, unless weathered surfaces are viewed. 

 In the coarse extreme, the nodules attain more than Y2 centim. in size 

 (fig. 0, PL II.) and at the same time the rock becomes less graphitic, 

 while the sericite increases proportionally in (juantity, and then the 

 colour chano-es from black to brown. When seen with reflected lio-ht, 

 the sericite-lamellae display a nacreous lustre. 



In a fine slaty variety a .transverse fi-acture of the rock has a 

 banded appearance through the alternation of quartz-felspar layers 

 with those of the coaly particles. The coarser variety is typically 

 developed near Oda, while the slaty one occurs at the village 

 of Honnogami. 



II. — The chloritc-amphiholite or spotted green schist is a thick, 

 imperfectly schistose rock of a grass-green coloiu* with an uneven 

 plane of schistosity. It is full of innumerable wdiite spots (7^-2 mm.) 

 on a green ground, presenting an aspect quite similar to currants in 

 a pudding (fig. 10. PI. 77.) F. Beckc seenjx to have found a similnr 

 structure in a mica-schist and gneiss rich in felspar-nodules from 

 Selitschani in Greece, and has given to it tlie name crisfhie structure O 

 from the likeness to cereal grains._^Our rock has such a striking 



1) Tschermak, Min. u. petro. Mitth, II Band, 1880, p. 43. 



