376 



DESCRIPTIVE MINERALOGY. 



Fig. 399. 



vein of granite traversing gneiss, and is associated with tourmaline, garnet, 

 and mica. Its colour is usually yellowish green. 



The crystals of chrysoberyl at this locality some- 

 times exhibit the primary form, and sometimes that 

 represented in Fig. 399, which was first noticed by 

 Dr. G. Troost,* the anariiorphique of Haiiy, in 

 whicli the shorter terminal edges are replaced by 

 the planes i: i on i 120°. Also Fig. 400, in which 

 the lateral, as well as the sliorter terminal edges 

 are replaced by single planes. M on s 125° 16'; 

 T on s 144° 44'. Most commonly, however, the crys- 

 tals are flat compound ones assuming a variety of 

 forms, as represented in Figs. 401, 402, 403, 



Fig. 401. Fig. 402. Fig. 403. 



apatite, feldspar 

 Fig. 



. 400. 



M 



M 



404, 405, 406, 407 and 408; the striaa 

 being in most cases distinctly marked, 

 as represented in the cuts. The man- 

 ner in which these are produced will, 

 I think, be understood by an inspection 



Fig. 404. 



Fig. 405. 



Fig. 407. 



* Journal of the Academy of Natural Sciences of Philadelphia. III. 293. 



