Mineralogical Journey. 



299 



of the other,) a perfect Ime of demarkation can be traced. From 

 these observations, I am led to infer, that the brown Quartz was first 

 deposited from solution, and surrounded the walls of the granitic 

 cavity with its crystals; and that the Tourmalines crystallized next, 

 to which succeeded the Talc and Felspar; and that, finally, the white 

 Quartz was deposited around the other substances. And we observe, 

 consistently with what is noticed concerning crystallizing fluids in our 

 laboratories, that the last portions of such fluids aflbrd crystals possess- 

 ing less perfectly the attributes of crystallization, — the white Quartz is 

 much inferior in transparency and delicacy of fracture to the smoky 

 variety. 



The large, loose crystals of Tourmalines aflect the general form of 

 trihedral prisms with convex faces, which are deeply striated. They 

 resemble each other very considerably, as respects transparency, 

 fracture and color, — being as clear, for the most part, as the intensi- 

 ty of their colors will allow ; free from flaws, except for a thin coat- 

 ing at their surfaces ; and where the crystal possesses any consider- 

 able length, green at one extremity and red at the other. They 

 have a tendency to break across at distances of about the diameter of 

 the prism, and with a highly conchoidal fracture so as to result in 

 fragments almost globular in shape, {gouttes de suif,) which are 

 quite free from flaws, and "of the finest water." Of these crystals 

 and fragments of crystals, I shall describe a few which appear to me 

 to be the most interesting. 



No. 1, is one inch and a half of the extremity of a green Tour- 

 maline, whose diameter equals its length. Its color is an intense 

 grass-green with a tinge of blue. It is regularly terminated by pol- 

 ished faces, as represented in the annexed diagram. 



No. 2, is a fragment, three quarters of an inch in length, by one 

 inch two tenths in diameter ; the extremities of which have been ren- 

 dered flat by the lapidary. Its colors are faint; and it exhibits the 



