Cupper-Tin Veins of the Akénolx- District. J 



the outcrops. The alteration of the slate into gi-een rocks is most 

 probably due to the action of the mineralizing solutions with which 

 the copper-tin veins are genetically connected, thus affording very 

 instructive data as to the genesis of the veins in question. It will, 

 therefore, bo fully discussed in a subsequent chapter. 



The slate is sometimes metamorphosed to phyllitic rocks by 

 dynamic processes. These are particularly well developed in the 

 environs of the Minamidani mine. All gradations, from carbonaceous 

 and green slates to highly schistose rocks, are observed. The 

 prevailing rocks are light grayish or light liluish green phyllites, 

 showing a characteristic silky luster, with well developed cleavage 

 structure. As can be observed under the microscope, abundant 

 felty sericite is developed and in places a fair amount of flaky 

 biotite (PI. n., Fig. 1). Both micas are characteristically arranged 

 along the cleavage planes. The rocks appear to liave undergone 

 recrystallization and granulation to a considerable extent, aljundant 

 fine grains of feldspar and quartz parallel to the cleavage plane 

 being visible. Yeinlets traversing the phyllites are common. Some 

 of the veinlets consist of granular quartz containing a small quantity 

 of epidote grains, while others are composed essentially of yellowish 

 coloured, pleochroic epidote in granular aggregation, in association 

 with a small amount of quartz grains. 



A bed of calcareous biotite -epidote sohist is exposed near the^ 

 Minamidani mine, which is probably a metamorphosed limestone 

 or calcareous shale. It is intercalated between the phyllites. It 

 is highly schistose in structure and the development both of flakes 

 of biotite and grains and crystals of epidote along the plane of 

 schistosity is very conspicuous. Microscopic crystals of garnet are 

 also developed. As a whole, recrystallized and granulated calcitc: 



