JOURNEYS THROUGH KOREA. 191 



outline, gradually merging into a general mass ; myrmekitic in- 

 tergrowtli with quartz is frequently observed on its periphery. 

 The quartz occurring in patches also gradually merges into a 

 general mass. These and many other peculiarities entitle it, as 

 I believe, to receive a new name, and I call it masanite. It is, 

 mineralogically speaking, a porphyritic jjlagioclase-greisen. It is 

 probably the marginal faciès of the laccolith. 



The masanite habitually appears at the base of the sheet 

 of porphyrite though both are defined by a sharp line of de- 

 markation and easily distinguished by contrast in colours (p. 

 22). 



The following is the result of an analysis carefully made for 

 the writer by Mr. G. Tsukamoto, of the Geological Survey : — 



101.59 



According to the system of Lœwinson-Lessing, we have the 

 following : — 



