o04 B. KOTO 



dark violet colour; hence the rock is locally named the '■'■ Murasald^^ 

 or violet rock. And this is most typically developed in the island of 

 Sikoku, especially in the neighbourhood of the city of ïokusima. 



The very first specimen that came under my notice, was brought 

 from Mount Otakisan, one mile to the south-west of the last-named 

 city; but afterwards many localities are added to the list of places 

 where it occurs, so that we are now able to trace out the geological 

 horizon of the Piedmontite-bearing rock everywhere within the 

 crystalline schists-system of that island. This rock is, however, not 

 exclusively confined to this region; it has also a wide distribution 

 in Musasi and Közuke provinces, on the main island (Honsiü). 



The Piedmontite occurs together with fine Quartz-grains, and 

 in virtue of its parallel disposition gives to the rock itself a schistose 

 structure, a vertical section of the rock presenting a regular banded 

 appearance formed by the fine alternation of Piedmontite and Qaartz 

 layers. 



The accessory components are Sericite (hydrous Mica of Prof 

 Bonny)(>), greenish-yellow Garnet, Rutile (wliich in some cases may 

 be easily mistaken for Piedmontite), non-striped Felspars (probably 

 Orthoclase), blood-red Iron-glance and also opaque crystals of the 

 same mineral; tourmaline has been nowhere found so far in my slides. 

 This is the typical Piedmontite-schist, and the general appearance of 

 a slide of this rock as seen under the microscope with an amplification 

 of 90 diameters is represented in Fig. I. In the Glaucophane-rock("), 

 the Manganese-epidote makes its appearance; but it is subordinate 

 in c[uantity to Glaucophane, and has its place often supplied by 

 common, yellowish-green Epidote. We shall first of all speak of the 

 Epidote in the Piedmontite-schist. 



(i) Miu. Mag. Vol. VII, No. 32, .Inly, 1880, p. 3. 

 (2) Log. cit. p. 86. 



