Metallogeny of the Japanese Islands. 7" 



The andésite of this kind is chiefly fonnd in the inner zone of the 

 Ryûkyû (Loo-choo) arc, where gohl mines are very hopeful, 

 especially in Satsuma, and to this nietallogenetic province the name 

 Satsuma is given. The Sado island, famous on account of the 

 rich Sado gold mine, is also supposed to helong to this province, 

 judging from the properties of the ores from the mine. 



Pyrite beds in Japan have for a long time been supposed to 

 be of aqueous origin, but at present they arc treated as bedded 

 veins. Their ore-bringer is not yet definitely known, but the 

 author believes that it may be serpentine or a like rock, just as 

 VoGT^^ explains the origin of the pyrite deposits of Norwaj^ as 

 related to gabbro. Such beds occur in the outer zones of South 

 Japan and the Eyû-Kyû arc. The largest of the kind is in the 

 Besshi mine, for which reason the author calls these regions the 

 Besshi Province. 



5. The Korean Province. 



The mineral resources of the Korean Province are gold and 

 copper, sometimes with cobalt, zinc, lead, arsenic, and tungsten. 

 The origin of the deposits in the Korean Province is most clearly 

 explained in "The Geology and Ore-deposits of the Holgol 

 Mine," an instructive paper by Prof. Koto."^ The Holgol mine 

 is situated in the northeastern portion of Hoan-haiclô in Korea. 

 The geology of Holgol and its neighborhood is composed of 

 highly metamorphosed argillite, calcareo-siliceous slate, limestone, 

 porphyritic granite, and basalt. Prof. Koto describes these rocks 

 in a most elaborate manner ; and, from various facts obtained by 

 this study, he comes to "the conclusion that the gold is juvenile, 

 and must have come from deep in the interior as an exudation 

 from the eutectic mixture of the granitic magma." 



Ores of the Korean Province occur in veins, or in contacts. 

 The gold ores in mineral veins are always quartzose. The quartz 

 is hard and translucent, generally being very poor in gold content, 

 except when sulphide minerals such as pyrite, galena, or zinc- 



1) Vogt : The Digest in " The Genesis ■ f Ore Deposits," p. 652. 



2) Koto : Loc. cit., p. 2. 



