Copper-Tin Veins of the Akénobé District. 53 



patches are often cut irregularly by the above-mentioned epidote 

 veinlets. Those ferruginous patches are evidently of secondary- 

 infiltration into the slate, and the epidote-bearing veinlets and 

 patches are of still later formation, since the former are traversed 



by the latter. 



A similar alteration is also typically developed in the green 

 slate in the environs of the veins of Hyakken and Sekiei. There, 

 veinlets and patches of epidote are abundantly found in the form 

 of parallel bands along or across the indistinct bedding-planes. 



Minor epidotization of the slate complex, microscopic as well 

 as macroscopic, is observed very extensively in this district. The 

 chloritizcd and silicified slate, already described, contains frequently 

 more or less epidote in association with quartz grains. 



The epidotization is evidently later than the chloritization 

 of the slate, because epidote usually invades chlorite flakes, and 

 veinlets of epidote cut the chloritized slate very sharply. On the 

 other hand, it is clearly prior to the sideritization which is described 

 in the next article, because epidotç veinlets are traversed definitely 

 by those of siderite. 



The fact that crystals and grains of epidote always occur in 

 association with quartz grains and the veinlets of epidote grade 

 frequently into those consisting exclusively of quartz, indicates that 

 the epidotization now under consideration is a special phase of the 

 silicification, already considered. 



(E) Sideritization of the slate. 



The wall-rocks, particularly the silicified slate just adjacent to 

 the veins, are commonly coloured reddish Ijrown to brown, and are 

 often penetrated by minute netted veins of a dark brown colour. 

 This is one of the most striking characters recognizable by every 



