274 FRANK D. ADAMS 



. It should thus be termed a grano-laurvikose or possibly, in 

 view of its somewhat porphyritic structure, a granophyro-laurvi- 

 kose. The proportions of the several minerals present, or mode, 

 as determined by Rosiwal's method were as follows: 



Feldspar - - - 77-24 per cent. 



Nepheline - - - - 4.40 " 



Hornblende - - - - 5-37 " 



Biotite - - - - 7.08 



Iron ore - - - - 1.81 " 



Sphene - - - - 3.29 " 



Apatite - - - - .81 " 



100.00 



For purposes of comparison the analysis of the pulaskite 

 (No. VIII) and of the nordmarkite (No. IX)" of Shefford 

 mountain were calculated into their respective ?iorms and the 

 position of these rocks in the new system of classification 

 determined. The pulaskite (No. VIII) is found to have the 

 following position : 



Class I, persalane. 

 Order 5, canadare. 

 Rang 2, pulaskase. 

 Subrang 4, laurvikose. 



The nordmarkite (No. IX), however is peralkalic and must 

 be classified as follows : 



Class I, persalane. 

 Order 5, canadare. 

 Rang I , nordmarkase. 

 Subrang 4, nordmarkose. 



It, however, lies just on the line between nordmarkose and 

 phlegrose, and might thus be best termed a nordmarkose- 

 phlegrose. 



It is thus seen that the rocks from Mount Johnson and from 

 Shefford mountain which, following Rosenbusch's classification, 

 have been called pulaskite, and which in this new scheme of 

 classification are pulaskase, are almost identical in composition 

 with one another and with the Norwegian laurvikite, and the 

 nordmarkite of Shefford mountain is very close in composition 

 to the nordmarkose of the original Scandinavian localitv. 



