14 Vol. XLIIL, Ar^ 5— T. Katô: 



liypidiomorphic and idiomorphic crystals is found in association 

 with hornblende. Sporadic apatite needles are present as a primary 

 accessory mineral. Insect-egg-like titanite, probably an alteration- 

 product of ilmenite, is widely scattered through tlie rock. The 

 ferromagnesian minerals are sometimes altered to ilbrous chlorite 

 showing an anomalous deep blue interference colour. Moreover, 

 veinlets of chlorit3 occasionally cut the rock. 



Similar rocks are found near the Higashiyama vein, as well 

 as adjacent to the Meisei vein, and in other places. 



Altered Dlorite. The dyke or elongated boss exposed between 

 tlie Daisen and Sekiei veins, together with the mass exposed 

 along the road leading from Akénobé to Fudono, belongs to this 

 category. 



These rocks are commonly decomposed to dark or light green 

 compact rocks, often showing no granular structure macroscopically. 

 Sometimes they are highly silicified and very hard. In places, they 

 resemble in mau}^ respects the green slate which is developed very 

 extensively in this district. When they are found in the green 

 slate terrane, their presence can scarcely be detected without the 

 aid of a microscope. 



Under the microscope, plagioclase is altered to kaolin, or more 

 frequently to saussurite or an aggregate of clinozoisite and epidoto. 

 Only sporadically is the form of the feldspar preserved, and the 

 characteristic twin-lamellae are observed between crossed niçois. 

 Hornblende is altered to chlorite and its original crystal form is 

 usually obliterated, although very rarely the mineral is found in 

 the form of bent and torn fragments scattered irregularly through 

 the rock. Chlorite often forms veinlets and streaks, occurring either 

 along the boundaries between crystals and grains of the altered 

 feldspar, or cutting them. In the silicified diorite, quartz occurs in 



