JOURNEÎS: THUOÜÜH KOREA. 71 



textures in different parts, some being brecciated, wliile one, 

 tlie true liow, shows ii fluidal texture. It is a coarse grayish 

 rock containing a few crystals of biotite, flesli-colored plagioclase, 

 and a large quantity of corroded grains and bipyramids of (juartz. 

 Tlie round quartz sliow^s the characteristic featui'es common in 

 quartz-porphyry. The groundmass consists of micro-granulo- 

 crystalline felsitic substance ; but the porphyritic components are 

 present in so large a quantity that the rock may properly be 

 called a c r y s t a 1 - p o r p h y r y. The feldspar phenocrysts easily 

 weather off leaving hollows presenting a rough rhyolitic aspect. 

 The mass stands vertically and extends from the northwest to the 

 southeast. This quartzporphyry-like rock contains microcline, or 

 plagioclase in lieu of orthoclase ; and I gave it the name nevaditic 

 masanite, which I have repeatedly mentioned in tlie first traverse/^ 

 I started from Mok-pho on February 20tli, 1901, when tlie 

 snow was fast melting and the wheat was sprouting in the full 

 vigor of spring. At about half the distance to Mu-an, porphyritic 

 masanite, having the appearance of red feldspar- porphyry, was 

 found at the head of a small inlet "'\ It seems to be one of the 

 preceding. 



Near Mu-an our ^ party rode along the boundary of two ml-an 

 formations. To the right we saw the flat-topped erosion-relic of 

 Kong-su-hong ^\ exposing, clifl's of a stratiform mass of red porphyry, 

 in which quartz and reddish feldspar are visible macroscopically 

 in the spherulitic and glassy groundmass with handsome fluidal 

 structure. The higher portion is capped with red claystone- 



1) See page '21. 



•2) Tang-cLhi (^ k^) in Sön-deuiig-iii (^ {1 M)- 



3) S- 7lc 1^ PI. X. fi'j. 3. 



