270 K. JIM BÖ : 



1 cm. in thickness. On some good crystals in Wada's collec- 

 tion, there are found oP, co p^ p^ Slc. Optical anomaly consists 

 of biaxial interference-figures in some part of basal sections. 

 Corrosion- forms in the form of sharp-pointed pyramids with 

 rounded edges are observed on the termination of some crys- 

 tals. 



Tanokamiyama in Omi.— At this locality there is occasion- 

 ally found greenish or bluish, transparent to translucent beryl, 

 whose length is sometimes 13 cm. and whose basal section has 

 sometimes a diameter of 3 cm. Good crystals of the beryl 

 show P, 2P2 , oP, &c. In one specimen with unstriated prisms, 

 there is to be seen on oP a hexagonal pit which might have been 

 produced by natural etching (Wada's collection). 



117. Orthoclase and Microcline. 



Tanokamiyama in Omi. — The potash felspars of this locality, 

 which form druses in pegmatite, are separable into following 

 varieties : 



a.) White translucent crystals, usually in Carlsbad and 

 Baveno twins, less frequently in Manebach twins and very seldom 

 in simple crystals. The Carlsbad twins always look like simple 

 crystals, for the Pöö of one individual is nearly parallel to oP 

 of the other. They are usually smaller than tlie Baveno twins 

 which attain a length of 20 cm. 



b.) Beddish-white to flesh-red crystals, occuring with topaz. 



c.) Glassy crystals mostly in Baveno twins, but rarely in 

 simple individuals, about 3 cm. in diameter. These crystals are 

 usually stained with manganese oxide. Less numerous than a 

 and b. 



