of Boston and its Viciniti/, 44.11 



It is rather tlifficultly frangible. 



The fragments are indeterminately angular, and sharp edged. 



It is pTiosphorescent, when two pieces are rubbed together. 



exhaling a peculiar odour. 



Its specifick gravity is about 2.636 



Chymical Character, 

 It is infusible before the blowpipe without addition 



Gploglcal Situation and Localities, 



It occurs massive, disseminated and in veins, in Grey-wacke, 

 Sienit, Greenstone, Argillite and Granite j also in rolled masses, 

 in angular pieces, and in small grains, at Roxbury, Milton, Cam. 

 bridge, Charlestown, &c. &c. Very fine specimens occur on the 



\ 



Dedham turnpike and in Brookline. It is one of the most fre- 

 quent minerals in this vicinity. 



Variety I, — Limpid Quartz, 



Limpid Quartz, Cleavelandy-p, 211. Rock or Mountain Crystal, Jameson^ 

 Vol. I. p. 143# Mountain Crystal, Kirwan^ vol. i. p. 241. Quart/., AUcirij p. 193. 



> 



External Characters, 



It is colourless. 

 It is irised. 



It is transparent. 



It is amorphous. 



I J 



Its surface is smooth and undulated. 



It is very hard. 



The fracture is conchoidal, and flat coachoidal 



It is easily frangible. 



