16 ART. 12. — ]î. KOTO : 



G). A few American and German writers ad vocale tlio primary origin 

 of tlic basalt-quartz. The niagnopliyric xenocryst of quartz in the 

 present rock seems to me to be the resorption-rest of highly heated 

 salic p!utonics, which have suffered magmatic invasion and also abyssal 

 assimilation in a basaltic bath. The quartz in question is found in 

 the basalt wiiich is in direct contact witli tlic porpliyritic granite. 

 Colorless, cquant, highly double-refractive and cuboidal grains (fig. Tj) 

 line the walls of microscopic vesicles filled with chlorilic matter and 

 calcite. They are probably datoliie. The quartz-bearing basalt is by 

 no means rare in Korea and South Mancliuria. Locality : Tlol-gol. 



There are at my disp)Osal two other rock-specimens worthy 

 of mention. They are aplite and meta-dioriie (PI. III. fig. 3). 



The former is a whitish, compact, quarter-millimeter-grained 

 rock of a granulitic fabric, composed of quartz and orthoclase, 

 and a little muscovite. It probably occurs as apophyses of the 

 On-jin-san granite and seems abundant at the contact of the stock 

 with the country-rocks. Probably the aplite dykes have some con- 

 nection with the genesis of the ore-deposits of the region. Hitherto 

 no attention has been paid to their occurrence. 



The latter is the so-called meta-diorite intruding into the 

 slaty mica-schist already mentioned. It is rudely schistose, being 

 composed of hornblende, plagioclase, apatite, ilmenite and biotite. 

 The hornblende is altered into composite needle aggregates (fig. 3.) 

 with secondary hiotUe in their centres. The plagioclase is also 

 altered into a mosaic of albite (fig. 3.). Xenomorphic apatite is 

 relatively abundant. Chimps of ilmenite with leucoxene margins 

 are seen. Microscopic inspection clearly shows that the rock is a 

 highly altered, typomorphic one. According to Prof. Becke, a 

 deep-seated plutonic may be lifted up to a shallower horizon and 

 this act gives to the rock components an opportunity for molecular 



