A Note on Glaucophane. 



By 

 B. Koto, Ph. D. 



Professor of Geology, Science College, Imperial University. 

 With Plate XII. 



It is proposed in this paper to give a brief description ofthat 

 interesting mineral — glaucophane, which the writer has collected during 

 his excursions in two summer- vacations; hence exclusively confined to 

 its occurrence in Japan. 



In the island of Shikoku, we see the crystalline schist- system 

 extensively developed, especially in the central mountain-chains which 

 trend from S.W.-N.E. Among the schists a very characteric rock is 

 found, which calls for our special attention, on account of its beautiful 

 colour varying in tinge from a greyish-blue to a purplish-blue. It 

 was formerly known among us as a cyanite-schist; but this is, how- 

 ever, not the case as wall become perfectly clear from the discussion 

 to which we shall refer hereafter. The typical specimens were brought 

 from Mount Otakisan near the city of Tokushima, and from the copper 

 mine at Besshi; the rock itself being not confined to the above- 

 mentioned localities, but being widely distributed in the region of the 

 crystalline schists. The glaucophane-bearing schist contains, besides 

 other ingredients, a long rectangular, olive-green epidote, yellowish- 

 green crystals of garnet, quartz, some felspars, rutile, also specular 

 iron, and the last, but not the least important one is piemontite or 

 manganese epidote. The glaucophane, when observed macroscopically, 



