154 S. SEKTYA AND Y. TCTKUOHT 



T. is a greenish-black rock taken from the rugged cliff of the 

 partially destroyed wall of Yugeta-yama, containing a small 

 quantity of iron-pyrites. 

 II. is a reddish coloured rock, very frequently met with within 

 the débris, especially in the conical mounds, somewhat 

 powdery at the surface, due to the fmnarolie action to 

 which it was subjected within the volcano. There is more 

 sesquioxide of iron in this rock than in the others. The 

 sample for the analysis was obtained from the ejected 

 masses near Tokoro-sawa, a ravine on the eastern side of 

 Bandai. 

 III. is the analysis of a rock from Bandai given by- S. Nishiya- 

 ma in his report to the Geological Survey, in 1887. The 

 exact locality of this rock is not mentioned. 

 From these results it will be seen that the rocks of Bandai are 

 nearly identical in their composition. We may, nevertheless, distin- 

 guish two types as we have already staled. ( )ne is a lighter coloured 

 rock, the structure being usually porphyrinic ; the porphyritic com- 

 ponents being pyroxenes and microtine plagioclase within a greyish 

 coloured ground-mass. A typical example of the first type may be 

 seen exposed on the side- wall of the new crater, as an extensive sheet 

 in the o-reat cliff forming now the western side of Kushigamine. A 

 similar kind ot rock was also found near the summit of Obandai. 

 Microscopically examined the greyish white groundmass is micro- 

 felspathic in character, with a small amount of colourless glass-basis. 

 All the mineral components are quite fresh. The plagioclase of this 

 rock was found to have a. specific gravity of 2'682. 



The other type of the pyroxene-andesife is a darker coloured 

 rock evidently more basic than the first and resembling Basalt in its 

 outer appearance; the glassy plagioclase being interspersed within the 



