Harrington — Composition of Canadian Amphiboles. 393 



of a Canadian winter, potassium carbonate can be used with 

 perfect safety. The combustion tube was protected by plati- 

 num foil, as recommended by Penn'eld, and heated by means of 

 a blast-lamp. The titanium was estimated colorometrically. 



In a general way the composition of the Grenville amphibole 

 resembles that of a bright green variety from Pongas in Finland 

 analyzed by Rarnmelsberg (I) and also one from the same place 

 analyzed by Bonsdorff (II). Their results were as follows :* 



I II 



Silica 46-12 46.26 



Alumina 7*56 11*48 



Ferrous oxide 2*27 3*48 



Manganous oxide 0*36 



Lime ... 13-10 13-96 



Magnesia 21-22 19-03 



Soda 2-48 



Potash 1-29 



Water. 1-10 



Fluorine 2'76 286 



98-50 97-43 



Sp.gr. 3-104 



Another Canadian amphibole which has been analyzed is that 

 occurring in the essexite of Montreal, a rock constituting por- 

 tions of the mountain. The specimen examined was from the 

 coarse-grained rock found in the Protestant cemetery and its 

 separation from the other constituents was effected in part by 

 means of a dense liquid. The mineral is black by reflected, and 

 brown by transmitted, light and shows marked absorption. The 

 hardness is between 5 and 6, the specific gravity, at 17*5° C, 

 3*159, and there is a well-defined prismatic cleavage. The 

 composition is given under I, while under II is given that of a 

 similar amphibole from the essexite of Mount Johnson, analyzed 

 by Mr. Nevil Norton Evans of this university : — 



I II 



Silica 39-23 38'63 



Titanium dioxide 4*53 5'04 



Alumina 14-38 11-97 



Ferric oxide _ 292 3-90 



Ferrous oxide 8*56 11-52 



Manganous oxide ._ 0*65 0-73 



Lime 11-70 12-81 



Magnesia 13*01 10*20 



Soda 3-05 3-14 



Potash... 0-98 1*49 



Water 0'36 '33 



99-37 99-76 



* Quoted by Hintze in his " Mineralogie," p. 1239. 



