Copper-Tin Veins of the Akénobé Distiict. 31 



The remaining three veins, Sekiei, Ilyakken and Shotoka, are 

 exposed on the same rngged mountain slope, far above the Daisen 

 vein. They lie at a distance of about 150 meters from one 

 another, and some of them are traceable for more than 300 meters 

 along the strike. 



Tiie Sekiei Vein which lies between the Nihonmatsu and 

 Hyakken veins is worked for both copper and tin ores ; especially 

 toward the deeper portions it seems to become richer in tin-stone 

 as well as in thin plates of wolframite, thus resembling the Daisen 

 vein in character. 



The Hijakken Vein contains rather insignificant quantities of 

 cassiterite and wolframite, and these only in deeper zones, so that 

 at present it is worked exclusively for copper ore. It often shows 

 a symmetrical crustified structure (Fig. 7), consisting of quartz, 

 fluorspar and chalcopyrite. The outermost or first crust consists 

 of quartz with specks of chalcopyrite and bornite, at depths in 

 association with very small quantities of wolframite and cassiterite ; 

 the second crust is composed wholly of fluorspar ; the third crust 

 is of massive chalcopyrite usually as an irregularly pinchmg and 

 swelling band ; the last crust is composed of barren quartz showing 

 in places a comb structure or a drusy structure with a lining of 

 rock crystals. Occasionally the vein in question produces a ring-ore 

 consisting of concentric layers oi quartz and sulphide ores, chiefly^ 

 chalcopyrite and zincblendo. It is very characteristic that t&T 

 ring-ore found m tliis vein contains little or no cassiterite, while 

 in the Daisen, Nihonmatsu and Sekiei veins this mineral forms 

 one of the essential components of the ring-ore. 



7li6 Shotoka Vein, though recently opened and only a httle 

 prospected, proves to contain almost no tin-stone, and is expected 

 to be worked exclusively for copper ore. 



