JOURNAL OF THE COLLEGE OF SCIENCE, TOKYO IMPERIAL UNIVERSITY. 

 VOL. XLIII., ART. 5. 



A Contribution to the Knowledge of the Cassiterite 

 Veins of Pneumato-Hydatogenetic or Hydro- 

 thermal Origin. A Study of the Copper-Tin 

 Veins of the Akénobé District in the 

 Province of Tajima, Japan. 



By 

 Takeo KATÖ, BigahusM. 



With 7 Plates and 11 Text-figures. 



I. Introduction. 



In the conrse of his investigation of the veins of the Akénobé 

 district, the present writer fonnd many interesting facts concerning 

 the genesis of tin veins in general. Particularly, the writer's atten- 

 tion was called to the presence of chalcedony^) in the principal 

 vein of this district as an important vein-stuflf in association with 

 cassiterite, and to the alterations of the wall-rocks characteristic of 

 hydrothermal processes. Consequently, he was led to the conclusion 

 that the copper- tin veins of this district were formed chiefly under 

 pneumato-hydatogenetic or hydrothermal conditions. These are the 

 same conditions under which the tin veins of the Suzuyama (or 

 Taniyama) mine were formed.^) It is highly probable that similar 



1) T. Katô, 'The ring-ore from the Akénobé mine, Province of T.ijima, Japan," Journ. 

 Geol. Soc. Tokyo, Vol. XXIV., 1917, pp. 35-41. 



2) T. Katô, " On the pneumato-hydatogenetic or hydrothermal formation of some cassiterite 

 veins. A microscopic study of the tin veins of the Suznyama mine. Province of Satsuma, 

 Japan," Journ. Geol. Soc. Tokyo, Vol. XXIII., 1916, pp. 145-164. 



