34 Vol. XLin., Art. 5.— T. Katö : 



presented by a shattered zone heavily mineralized with chalcopyrite 

 in the form of networks, streaks, patches and impregnation, 

 accompanied by varying amounts of quartz. Sometimes they occur 

 as simple fissure-filling veins showing an irregular massive, or in 

 places banded, structure. Quartz is the principal gangue mineral, 

 and chalcopyrite the chief ore. In the roof- vein, insignificant quan- 

 tities of wolframite and cassiterite are associated. 



Another small vein cutting the two N.-S. veins diagonally, 

 i.e., striking N. E. and dipping northwestward, is found on the 

 northern side of the intersection of the two veins. It is a fault 

 vein, accompanied by conspicuous slickensides, brecciation and 

 shifting of the cut veins, and is richly mineralized with chalcopyrite, 

 especially at the intersections with the preexisting veins. 



The above-mentioned veins are worked chiefly for copper ore, 

 but a small quantity of tin ore i3 also extracted from them. 



Tiie Meisei Vein, which lies about 600 meters north of the 

 Daidô mine, belongs to the same category. It strikes N.-S. as in 

 the Daidô veins, but dips westward. In places it is represented 

 by a shattered zone, giving rise to a stockwork deposit, from which 

 very ricli tin ore was much extracted, especially from the oxidized 

 zone stained with limonite. At present, this mine is temporarily 

 out of work, but it wiU be worked again by open- cut in the near 

 future. On the hanging-wall side of the vein, adjacent to it, a fault 

 with the same strike is developed. A gabbroid diorite is exposed 

 along the hanging wall of the fault, being cleanly cut by it. 



All veins belonging to the Daidô vein group, such as those of 

 the Daiso'u group, are enclosed in the green slate complex. 



