138 B. KOTO 



Fig. 4. — A garnet- rliombohedron found in the graphite- sericite-schist. 

 An attempt is made to show a peculiar mode of arrange- 

 ment of rutile needles within the crystal (page 91). 



Fig. 5. — Is an outward appearance of a polished specimen of the 

 typical spotted graphite-sericite-schist, drawn to natural size. 

 A cursory glance at the figure reminds us of the " Garben- 

 schiefer" of Saxony. The interstitial spaces are occupied by 

 black coarsely lamellar-fibrous flakes of sericite. Through 

 weathering, the rock acquires a brown colour, and appears 

 just like a biotite-mica-schist of a common type. Under the 

 microscope, the green mica reminds us of chloritoid, but the 

 comparatively low grade of its hardness compels the writer 

 rather to refer it to a green sericite-like mineral (phengite). 



Fig. 6. — The flecks of the above schist are the deformed crystals of 

 felspar, in the combination of the faces T, F, I, and y, as 

 shown in the figure. The individuals of the felspar lie parallel 

 with the vertical axis to the plane of the schistosity of the 

 rocks. The plane of the basal cleavage shows a pearly 

 lustre ; and a few traces of the cleavage apparently parallel 

 to the clinopinacoid are also discernible (page 97). 



Fig. 7. — An irregularly outlined crystal of the felspar-dots already 

 referred to in ß.g. 5. The figure brings to view a most 

 peculiar fluidal arrangement of coaly dust ; the clear external 

 zone seems to be formed by the secondary enlargement of the 

 felspar (page 97). 



Fig. 8. — The most common type of the crystals of tourmalines found 

 in the graphite-sericite-schist, showing the acute, deeply 

 coloured pole at one end, while the obtuse termination is of a 

 lighter shade (page 100). 



Fig. Pj a. — Represents a case of the parallel growth of two tourmaline- 



