PHYSIOGRAPHY. 



Chrysoberyl. 



127 



CHRYSOBERYL. Prismatic Emerald. 

 Primary form. Right rectangular prism. 

 Secondary forms. 



Fig. 132. 



Fig. 133. Fig. 134. 



Haddam, (Conn.) 



Siberia. 



Fig. 132, the primary having the terminal plane oblite- 

 rated by the extension of the planes i, which replace the 

 shorter terminal edges, i on i = 120, anamorphique of 

 HAUY. Fig. 133, in addition to the new planes i, the ter- 

 minal angles and the lateral edges are replaced, o on i = 

 133 19', H. o on M =136 41', H. M on s = 125 

 16'. Fig. 134 is the octovigesimale of HAUY. n on o = 

 163 53' H. T on n=126 8' H. 



Cleavage distinct parallel to the primary form ; effected 

 with ease parallel to M, but with difficulty in the direction of 

 T and P. Traces of a diagonal cleavage. Fracture con- 

 choidal. Surface, the vertical planes striated longitudinal- 

 ly ; the remaining ones generally smooth and even. 



Lustre vitreous. Color asparagus-green, passing into 

 greenish-white, olive green, and yellowish-grey. Streak 

 white. Transparent . . . translucent : sometimes exhibiting 



