164 Watanabe — Babingtonite from Japan. 



The indices of refraction were measured by Becke's 

 method by means of the standard solutions, which were 

 available through the courtesy of Prof. A. F. Rogers. 

 The minimum value is between 1.710 and 1.720, and the 

 maximum a little greater than 1.740. The intermediate 

 principal index lies between 1.720 and 1.730. 9 Thus the 

 three principal indices are approximately: 



a = 1.715±0.005 

 fi = 1.725±0.005 

 7 = 1.740+O.OOx 



Optically biaxial and positive. Cleavage is perfect 

 parallel to c(001), and less perfect parallel to a (100) and 

 &(010). The hardness is almost equal to that of ortho- 

 clase, or about 6. Before the blowpipe, the thin edges 

 easily fuse to magnetic globules. The substance is not 

 affected by common acids. 



Tohoku Imperial University, Sendai, Japan. 



9 Determined by S. Tsuboi's method, Jour. Geol. Soc. Tokyo, vol. 25, p. 38, 

 1918. 



