298 Mineraloglcal Toitrney. 



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lite, completely studded over, and penetrated by, finely colored crys- 

 tals of green and red Tourmaline ; drusy fragments of granite, whose 

 cavities were lined with the same minerals,— the Feldspar being nearly 

 opac^ue, of a delicate whiteness and possessing the beautiful cJiaioyement 

 which this species often presents ; crystals of greyish white Quartz, 

 several inches in length and thickness, and penetrated by Tourma- 

 lines ; and, finally, loose crystals of Tourmaline and RubeUite, from 

 a quarter of an inch, to two inches, in diameter. Thus we followed 

 the digging, in every direction, so long as it continued to afford these 

 products J w^hich it did, until within a short distance of the rock. 

 The majority of pieces, however, seemed to occupy a vein one foot 

 wide and three feet long, by about two feet in depth. From this 

 state of things, it seems fair to conclude, that the granite here, when 

 in a state of integrity, must have possessed a drusy cavity open 

 from above j and it is by no means improbable, that the loose speci- 

 mens of Tourmaline, smoky Quartz, he. which wove found 

 the sides of the hill on the discovery of the locaUty, had their origi- 

 nal repository in this cavity. 



about 



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kinds, 



Quartz 



notwithstanding they were formed in the same crystalline vault, there 

 are such remarkable dijfferences both in the modifications which tliey 

 offer and in other respects, as clearly to evince, that the crystallization 

 of tlie one, was subsequent to that of the other. The brown Quartz 

 is much clearer and better crystallized; and its crystals are singularly 

 characterized by the alternating re-appearance of the prismatic faces, 

 after the pyramidal faces have begun to form. A fragment of a crys- 

 tal measuring two inches and a half across Its prismatic faces shews 

 tliese alternations, repeated for a great number of times, and forming 

 steps in some places, one eighth, of an inch in depth. Moreover, 

 these crystals are entirely free from any penetrating minerals; while 

 the white crystals show nothing of the above peculiarity in their 

 structure, — being uniformly tabular in their shape. Besides, the 

 larger ones are wanting in that perfection of fracture and tendency to 

 a pyramidal termination, (except at one extremity,) which charac- 

 terize the smoky Quartz; and are every where penetrated by crystals 

 of Tourmaline and often by Felspar and Talc. Farther, 1 possess one 

 crystal of brown Quartz, having a crystal of the other variety attached 

 to it, but between the two, notwithstanding the coincidence of their 

 prismatic axes, (one crystal being placed directly upon the summit 



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