JOURNEYS THROUGH KOREA. 67 



corroded edges and embayments, which fact unequivocally proves 

 the igneous origin of tliis mica- schist ^\ The main mass consists 

 of finely pulverized and polarizing particles mixed with membranes 

 of sericitic mica produced by the shearing motion of the earth's 

 crust, ai'ound the porphyritic quartz whicli itself did not escape a 

 partial shattering by the general deformative action. 



iv. The fourtii is a crushed carbonaceous slab=?tone in which 

 are imbedded bluish vitreous dots of quartz. The crushed quartz 

 fragments show pronounced undulatory extinction. Feldspars are 

 drawn out and changed into aggregates of muscovite. The 

 general mass is exactly the same as a section of common slate. 

 It is no doubt of clastic origin, 



v. The basal rock of the graphitoid bed is a blackish grit 

 which, when examined under liigh powers, appears to consist of 

 highly cataclastic quartz grains cemented with crushed products 

 besides muscovite and graphitic particles ; and the whole is 

 variously traversed and healed by newly crystallized quartz and 

 sericite. A few tourmaline grains are found. In the present 

 deformed state, it is impossible to say whether the rock was 

 originally igneous or sedimentary. 



vi. A grapliitoid bed"^ of considerable thickness occurs 



1) Salomon htis lately disciisseil the origin o£ sericite-schist attributing it to the myloniti- 

 zation of a quartz-porx)hyry. He gives the analyses of both rocks and finds that the former is 

 poor in soda and other alkalies, while on the other hand it is " sjiturated with alnmina " 

 showing that orthoclase is still largely represented in the sericite-schist. " Die Enstehnng der 

 Sericitschiefer in der Val Camonica (Lombardei)'. Bericld neber die A'.TX Versammlunçt des 

 OherrJieînischen geologischen Vereins zu Lindau, 1907. 



2) The present graphitoid is, mineralogically speaking, a variety standing midway l)etween 

 graphite and anthracite. The bed or seam of it is 30 feet strong, thongh the main l)ulk is 

 built up of various siliceous admixtures. The foot-wall of the seam is composed of a fine 

 sandstone, while its hanging wall is of clayslate. According to Inouyé {loc. cit.), the complex 

 strikes N. 70° W. with the dip N.E. 70°. A chemical analysis made of the graphitoid gave the 

 following result : — 



Water. Volatile Matter. Coke. Ash. S. Sp. Gr. 



9.78 8.29 58.02 24.91 0.38 1.95 



The color of the ash is yellowish-white. The graphitoid is brittle and non-caking. 



