Notices of some Minerals. 339 



begins and the other terminates. Small olive-green stains, 

 in dots, pervade the mass, most probably derived from some 

 foreign matter ; but too minute in quantity, and too inti- 

 mately mixed with the stone, to be separated. 



Texture granular. Lustre between glassy and resinous. 

 Translucent on the edges. 



Hardness about 6, or not much softer than felspar. 

 Specific gravity 2-8617. 



It was analyzed in my laboratory with great care by Mr. 

 John Tennant. The following table shews the constituents 

 of the American variety, and of the Lapland amphodelite as 

 analyzed by Nordenskibld. 



100 97-85 



The silica in both specimens is precisely the same. The 

 sum total of the bases is the same in both, though the 

 weight of the individual constituents differs. The follow- 

 ing formulas represent the constitution of both varieties : — 

 Lapland 3 A1S + (£1 Cal + ■* Mg + f- t f) S 

 (Can " 

 American 2 A1S + I Mg \ S°- 



I think it probable [that both of these varieties contain 

 foreign matter, and that the differences between them are 

 owing to this circumstance. 



VI. — WEISSITE. 



The name Weissite was given by Trolle Wachtmeister to a 

 mineral which occurs in kidney-shaped pieces, about the 

 size of a hazel-nut, in chlorite slate, at Erick Matt's mine 

 Fahlun, in Sweden. For a description of this mineral I 

 refer the reader to my Mineralogy, vol. i. p. 282. 



Towards the end of last year, I got from Dr. Holmes, of 

 Montreal, a specimen of a mineral from Potton, in Lower 



z2 



