SCHISTS 



.TOURNEYS THROUGH KOREA. 115 



underlaid by a complex of green marl and white tuffite, making 

 an anticlinal near the well-known Man-mal-Txoan pass with its 

 stone gate (the strike N. 30" E., the dip N.W. or S.E.). 



The northern flank is again bnilt np of orthogneiss, though 

 * eyes ' are wanting here. It is a coarse but hard reddish 

 granite. The microscope discloses that the idiomorphic oligoclase, 

 which is altered into sericite, is enclosed by orthoclase and 

 microcline. The orthoclase likewise shows signs of muscovitization, 

 while the microcline is fresh with a reticulated structure. Biotite 

 is altered into epidote and chlorite, and dragged into tissue-like 

 bands. Crystals of rather large apatite and small zircon are present. 

 Quartz is reduced to cataclastic grains. It is an alkaline orthogneiss. 



Near the provincial capital, Chyön-jiju, the rock is overlaid by 

 a complex of Mesozoic sericite schists. Mesozoic 



One member is a foliaceous para-hlotlte-schist, consisting of 

 fine biotite scales alternating witli quartzose bands. 



The second is a grayish graphite- schist with silky lustre on 

 the plane of cleavage. The main bulk consists of quartz with a 

 little plagioclase, showing h ornfels- structure. The rest is made 

 up of sericite membrane with coaly particles. The granulated 

 surface of cleavage is due to quartz grains. 



The third is a fine granular schist of nephrite-like appearance. 

 Microscopically it consists of quartz and reedy tremolite with 

 poikilitic grains of quartz. Feldspars are wanting, but drop-like 

 titanite is present. This is tremolite- schist. Mr. K. Inouye found 

 a schist of similar appearance in the gold region of Keum-cju ^\ 

 not far from here. The rock, however, contains malacolite instead 

 of tremolite. Both rocks seem to have been altered from an 

 impure limestone. 



1) ± m 



