C!opper-Tin Veins of the Akénobé District. 25 



intricately intersecting vcinlets and in irregular grains filling h 3 

 interstices between the altered feldspar and other constituents. The 

 quartz shows often undulatory extinction and is cut by stringers 

 of clinozoisite squeezed out from the surrounding saussurite. These 

 facts suggest that the rock has undergone conspicuous dynamic 

 action after tlie infiltration of quartz. 



Schistose Diorite. The diorite in this district shows in places 

 a remarkable schistose structure. The schistose diorite is extensively 

 developed on tlie ridge between Akénobé and Mikobata, particularly 

 in the environs of the abandoned pits of the Kasei mine. It is 

 evidently a faciès of the main diorite fron\ which innumerable 

 ofishoots are led out. 



As can be observed under the microscope, prismatic crystals of 

 hornblende witli no terminal faces are arranged in somewhat parallel 

 orientation, the feldspathic constituents filling the interstices between 

 the hornblende crystals and also forming colourless bands and 

 streaks in alternation with the layers composed of aggregates of 

 prismatic hornblende (PI. IV., Fig. 6). The feldspar has undergone 

 intense granulation, and is changed to aggregates of fine grains 

 admixed with fair quantities of fibers and flakes of secondary 

 sericite, in association with prismatic crystals and grains of 

 clinozoisite and epidote. The hornblende is light coloured and 

 distinctly pleochroic, light greenish yellow to light green. It shows 

 characteristically corroded forms, embayed by feldspar (PL IV., 

 Fig. ß). Pyrrhotite in small specks is widely scattered through 

 the rock. The rock is often cut by quartz veinlets containing a 

 small quantity of flaky muscovite. 



Diorite Mylonlte. The diorite in this district, especially that 

 forming the main stock which is exposed on the ridge between 

 Akénobé and Mikobata, has undergone intense dynamic processes. 



