ON IHK SO-CALLED CRYSTALLINE SCHISTS OF CHICHIBU. 85 



(b) The Lower Division. 



Normal Sericite-schist. 



It is u grayish- white, thick-foliuted rock with a wavy sweep on 

 the sheen surface. Slabs show numerous prominences of a yellowish 

 tinge, owing to the presence of epidote crystals. 'J he cleaved face 

 has a silky lustre, due to the parallel arrangement of fibrous scales 

 of sericite. The rock-ingredients yre quartz, some felspars, sericite, 

 calcilc, a ijeUowisJi-greefi epidote, iron-tjlance, iron-mica, and lastlv, rutde ; 

 apatite, the most common accessory component in the massive r«)cks 

 and schists is remarkable by its absence in the rock-series now in 

 consideration. 



The greater part of the rock-mass is made uij of quartz-yraiiis. 

 Their external boundaries are quite irregular, and appear as if one 

 overlapping the other. By a simple macroscopical examination, the 

 part occupied by quartz presents almost an homogeneous aspect, and 

 gives an impression as if it were occupied by solidified masses of the 

 colloid silica of the diagenetic origin. ]>y the use of an upper Nicol, 

 the state of things is found to be quite otherwise ; the apparently homo- 

 geneous mass resolves itself into an aggregate of quartz grains, each 

 having optically different orientations, and in many cases showing 

 a marked undulatory extinction. The granulation of the cpiartz is 

 particularly pronounced where the rock-masses have been subjected 

 to minute foldings and flexures, whereby the dismembered parts 

 are more or less pushed further on one side or the other. This 

 complicated condition may be best seen in fig. 1. VI. II. which is 

 drawn from a transverse section of the glaucophane schist from 

 Otakisan, Awa, — the rock probably belonging to the same geoloo-ic 

 age as the Lower Sambagawan schists. On looking at the figure, it 

 is evident that the sericite (hydromica) was originally arranged in 



