Review of Dana's Mineralogy. 



381 



shown in fig. 13. Some of the individuals from this locality- 

 are six to eight inches in length, and always macles. 



Idocrase. — Amherst, in New Hampshire, furnishes the form 

 represented in fig. 14. 



Andalusite. — A crystal of Andalusite from Westford, Mass., 

 shown in fig. 15, was measured by Mr. Teschemacher, P : a 

 144-50. 



Fia. 14. 



Fig. 15. 



Fig. 13. 



M 



M 



Chondrodite. — We have at last a figure and the angles of 

 this rarely crystallized species as follows, (Pig. 16.) 



" Primary form, an oblique rhombic prism; M : Mz=zll2° 12'? 

 Haiiy. Secondary form : M : M=112° and 68°, M : e=136°, M : e= 

 157°, e : e (adjacent)=80°, a : a (over the summit)z=85°, e : e=89°, 

 e : e (over a)=127°, a on the edge e : ezr:167. The figure is drawn 

 from a specimen in the collection of J. A. Clay, Esq. of Philadelphia. 

 The angles were taken with the common goniometer." (p. 388.) 

 Fig. 16. Fig. 17. 



Beryl. — The beautiful and almost unique beryls from Had- 

 dam, described by Prof. Johnston (in this Journal, Vol. xl, p. 401) 

 are rarely modified by secondary planes. Fig. 17 shows one with 

 the planes a' a" and e. The dotted line marks the boundary 

 between the pellucid and milky portions. 



Sillimanite. Epimecius Sillimanianus. 



This interesting mineral has been the subject of much specu- 

 lation. The following figure and angles are taken from a speci- 

 men in the cabinet of B. Silliman, Jr. and found at Norwich, Ct. 



