282 GEOLOGY OF TONOPAH MINING DISTRICT, NEVADA. 



tuff*. The gangue is quartz, with calcite, rarely with dolomite and gypsum. 

 The ores are chiefly native gold and silver, and argentite, associated with chalco- 

 pyrite, pyrite, blende, and galena; rarely stephanite, pyrargyrite, marcasite, and 

 arsenopyrite. At the Kosen mine, in Tajima province, the veins are connected with 

 "propylite'' dikes in granite. The gangue is quartz, the ore auriferous argentite, 

 with pyrite and galena. The Tasei mine, Tajima province, is in "propylite," 

 rhyolite, and Tertiary tuffs. The gangue of the vein is quartz, with some calcite 

 and rhodochrosite. The ores are argentite and native gold and silver, with 

 chalcopyrite, pyrite, galena, blende, and malachite. At the Kanagase mine, not 

 far distant, the country rocks are similar; the gangue is quartz and calcite, and 

 the ores are chalcopyrite, bornite, pyrite. tetrahedrite, argentite, galena, stibnite, 

 pyrargyrite, blende, bismuth, and native silver and copper. At the Omori mine, 

 Iwami province, the rocks are bypersthene-quartz-andesite, andesite agglomerate, 

 and Tertiary strata. The ores are in veins and impregnation deposits. The gangue 

 is quartz; the ore native silver, argentite, siderite, malachite, and auriferous and 

 argentiferous chalcop3 r rite. The Okuzu mine, in Ugo province, is in Tertiary 

 tuff and augite-andesite. The gangue is quartz: the ore auriferous chalcopyrite, 

 with pyrite and rare blende. Silver is rare. At the Mizusawa mine, Ugo province, 

 the country rock is augite-andesite and Tertiary strata. The ore is a mixture of 

 barite. argentite, blende, galena, pyrite, quartz, calcite, chalcopyrite, and probably 

 stephanite. At the Tsubaki and Hachimori mines, Ugo province, veins in andesite 

 carry ores like the last named. At the Shirayama mine, Ugo province, veins in 

 Tertiary tuff and augite-andesite have a gangue of quartz and barite, and contain 

 argentiferous "galena, blende, pyrite, and chalcopyrite. At the Innai mine, Ugo 

 province, the country rock is Tertiary "propylite." the gangue is quartz and 

 rhodochrosite, the ore minerals stephanite, argentite, pyrargyrite, chalcopyrite, 

 pyrite, galena, and blende. At the Towada mine, in Rikuchu province, the vein 

 occurs in Tertiary tuff, associated with augite-andesite. The ore is auriferous 

 argentite and chalcopyrite in a clay and gypsum matrix. At the Omaki mine, 

 Ugo province, the country rocks are Tertiary tuffs and andesite. The ore is 

 argentite, silver oxide, copper and iron pyrite, and galena, with barite and g\'psum 

 as gangue minerals. At the Hisanichi mine, Ugo province, is a vein in Tertiary 

 strata and augite-andesite. The ore is galena, chalcopyrite, blende, and pyrite. 

 Many of the important metalliferous veins in northern Japan and Chugoku 

 are also in rhyolites. In the Kanahira mine, in Kananomura, Kaga province, the 

 veins are in rhyolite; the gangue is barite and quartz, the ores are native gold, 

 blende, and pyrite. At the Matsuoka mine, in Ugo province, the ore is a stockwork 

 at the contact of rhyolite with Tertiary strata; the ores are argentiferous galena, 

 blende, and pyrite, carrying gold. At the Handa mine, Iwashiro province, the 



