268 S- ^^'i'ö. 



pleochroic. The interstitial, half-granulated feldspar, probably albite, 

 is visible through the flocculent chlorite ; and the whole rock is pep- 

 pered through with almost colourless grains and slightly yellowish 

 crystalloids of epidote. 



B. Mica- Schist. 



The mica-schist, interbanding with the amphibolites, may at 

 once be discriminated from those of the complexes of mica-schists 

 and granulitic gneisses of the Takanuki series, by its coarse-lamellar 

 texture and glossy iron-black lustre. Common mica-schists are, 

 as a rule, highly quartzose, and the biotite that enters into their 

 composition is usually scaly ; this rock, however, is highly micace- 

 ous, being for the greater part made up of lamelJse, but not the 

 hexagonal scales, of biotite. The rocks classed here as mica-schist 

 exhibit within narrow limits a considerable diversity, as well in their 

 outward appearnnce as in their microscopic aspect. Therefore, they 

 may be conveniently divided into two varieties. 



«) A coarse-lamehar, somewhat wavy structured variety is basic 

 and rich in feldspars ; the tombac-brown lamellae of mica lap one over 

 the other, forming a thick, continuous membrane, and constitute 

 undulating zones with the quartz-feldspar aggregate. A cleaved 

 surface is not even, but lumpy or nodular, due to the local swellings of 

 quartz in the schist, into spindle-shaped assemblages well seen on the 

 transverse fracture, and these give a gnarled or knotted appearance to 

 it. In its outward aspect this rock resembles the so-called " Garhen- 

 scliiefer,'" or the graphite-sericite- schist of the Sambagawan series of the 

 author,^ differing, however, from the last- mentioned in the presence of 

 true biotite instead of a green, fibrillated, sericitic mica. The feldspar 

 occurs in poly somatic forms; simple twins are often made visible by 



1 On the so-called Crystalline Schists of Chichibu; This journal, vol. II, p. 97. 



