312 B. KOTO 



I am rather inclined to think that the schists containing the yellowish- 

 green Garnet in Sikokii may represent a metamorphic faciès of some, 

 other schists. 



EXPLANATION OF PLATE XXI. 



Fig. 1. A slide of Piedmontite-schist taken parallel to the plane of schisto- 

 sity of the rock, sliowing purple Piedmontite needles, hexagonal 

 plates of Iron-mica (lighter shade of a blackish colour in the 

 figure), dark Iron-glance, fibrous Sericite-lamellte, Rutile needles 

 together with round ci'ystals of Garnet. The matrix of the rock 

 left blank in the figure consists of an admixture of Quartz and 

 Felspars. Magnified 90 diameters. 



Fig. 2. A usual form of Piedmontite crystals with predominating faces of 

 il/, T, i, together with the hemi-pyramid. Such perfect crystal- 

 lographic forms are not uncommon in the reck. 



Fig. 3. A clinopinacoidal section with predominating faces of T and 

 i usually met with in rock-sections, showing at the same time few 

 cleavage-traces parallel to M and T. 



Fig. 4, Fig. 5, and Fig. 3. represent some of the remarkable forms result- 

 ing from the intergrowth and supergrowth of crystals of various 

 sizes, whereby the outlines of sections become very irregular. 



Fjg. 6. Twins of a common typo with general forms of crystal-individuals, 

 showing the scheme of optical orientation. 



Fig. 7. A light yellowish-green Epidote, having a rosy colour in the 

 centre, caused by an accumulation of the pigment of a manganese- 

 oxide. It represents the transitional stage of Piedmontite and 

 common Epidote. 



Fig. 8. A section of the rhombic-dodecahedron of Garnet with admixtures 

 of violet Piedmontite needles, clumps of dark Iron-glance, hexa- 

 gonal plates of Iron-mica, knee-shaped twins" of Rutile needles and 

 highly vitreous gi'ains of Quartz within the crystal of Garnet. 



