Copper-Tin Veins of the Akénobô District. 29 



out. Those now being worked are Daisen, Nihonmatsu, Sekioi, 

 Hyakken, Shôtoku, Daidô, Ebisu, Daikoku and Minamkîani. The 

 Daisen vein is the champion lode and produces more tin ore than 

 any other in this district, as well as some quantities of copper ore. 

 Nihonmatsu, Sekiei and Daidô veins also produce tin as well as 

 copper ore. The veins of Hyakken, Shôtoku, Ebisu and Daikoku 

 are worked for copper ore, although a small quantity of tin- stone 

 is commonly contained in them. The Minamidani deposit belongs to 

 a quite different type,0 and is worked exclusively for copper ore. 



The important veins in this district may be divided into three 

 groups according to the strikes, viz., (1) the Daisen vein group or 

 the veins striking N.W.-S.E. ; (2) the Daidô vein group or the 

 veins striking N.-S. ; (3) the Daijukô vein group or the veins 

 striking E.-W. 



The Daisen Vein Group. 



The Daisen vein and its parallel companions, namely, Nihon- 

 matsu, Sekiei, Hyakken and Shôtoku veins are most important as 

 ore-producers at the present time. They all strike N. 40^-50° W. 



1) The Minamidani deposit lies on the northwestern flank of the peak of Suruga-mine, at 

 n height of almxt GOO meters above the level of the Akénobé Eiver. It is abont 4 km. north- 

 east of the village of Akénobé. It is found in the Paleozoic terrane. but the country rocks are 

 remarkably different from those in the copper-tin vein area. Besides green slates, phylhtxc 

 rocks including calcareous phyllite with much epidote, radiolari..n slate, etc.- evidently more or 

 less dynamo-metamorphosed slaty rocks, are dominant. They strike N. E. and dip toward N. W^ 

 nt 30^-40- the general strike and dip thns coincide with those in the copper-tm vein area 

 The depoJit is a bedded vein of compact cupriferous pyrite having a lenticular form. 3 meters 

 or more thick in the thickest portion, and contains 4 to 5 per cent of copper on an average 

 Magnetite occurs in admixture with pyrite, and in places it forms black compact masses m pin ce 

 of pyrite Toward the boundary of the deposit the ore becomes quartzose and grades finally 

 into quartz masses. The deposit is much faiüted. Near the deposit under consideration a large 

 DorDhvrite dyke is found (p. 25). 



This belongs to a quite peculiar type of ore deposit, being a dynamically metamorphosed, 

 bedded epigenel^c deposit, e^lently different in origin from the copper-txn veins m the Akenobe 

 cltrictwth which the present paper deals. It is noteworthy that a deposit o the sarne 

 laracL il met with on the main level driven ..long the Otaké vein, which belongs to the 

 Taisen vein group, the latter cutting the former (p. 33). 



