72 Vol. XLIU, Art. 6. — S. Tsuboi : 



Albite 17.8 



Anorthite 29.2 



Diopside 12.4 



Hyperstbene 19.7 



Magnetite 4.9 



Bmenite 2.0 



Apatite 0.3 



Ratios. 



Sal 

 Fern 



F 



Na,0^+K,(y 

 CaO' 



Na.O' 



= 1.57 Class 'III 



= 0.19 Older 4' 



= 0.37 Ptaug 4 



= 0.15 SubraDg 4' 



According to the C. I. P. W. quantitative system, the rock 

 belongs to 'III. 4'. 4. 4'., an unnamed subrang. 



Name of Mock. — The characteristic feature of the present rock 

 is well seen in Osann's formula as well as in the norm. In the 

 values of a, c, and /, the present rock accords with " plagioclase- 

 basalt of the Eoyat type "^\ from which, however, it is decisively 

 distinguished in the value of k. 



Normatively, the present rock is characterized by labradorite 

 AbjflAn,.^ and contains quartz molecules in such quantities that 

 it is classified in the quardofelic order in the quantitative system. 

 The rock is, therefore, to be classed as " bandaite "'^ according to 

 Iddings's term. But as the present rock is transitional to " basalt '* 

 in its less quaric and more femic characters, it may properly be 

 called " basaltic bandaite." 



1) OsANN, Tschermalc's Min. u. Petr. Mitth., Bd. XX., S. 451, 1901. 



2) Iddixgs, Igneous Rocks, Vol. II., p. Ill, l'J13. 



