62 ROYAL SOCIETY OF CANADA 



One of the best developments of this white syenite is to he found on 

 the summit of the ridge of the Blue Mountain, about the middle of 

 lots 13 and 14, con. X of Methuen, where it is seen in large exposures. 

 Under the microscope it is seen to be composed chiefly of albite, with a 

 considerable admixture of microcline and a very small amount of nephe- 

 line. Muscovite and magnetite, both very subordinate in amount, are 

 the only other constituents. Its structure and the character of its con- 

 stituent minerals is identical with that of the nepheline syenite already 

 described. 



A chemical analysis of a specimen of this rock which, however, still 

 contains a considerable amount of accessory nepheline, by Professor 

 Norton-Evans of McGill University, gave the following results: — 



SiO^ 59.68 



TiOj none 



AlA 23.48 



FeA -59 



FeO 37 



MnO none 



CaO .26 



MgO .21 



K^O 4.68 



Na/) 9.52 



P2O5 none 



CO2 .04 



H2O .66 



99.49 



The norm of the rock when calculated is found to be as follows; 



Orthoclase 27.80 per cent. 



Albite 49.25 



Anorthite 1.25 



Nepheline 16.76 " 



Olivine .45 



Corundum 2.24 " 



Magnetite .93 " 



98.68 

 Water .6G " 



99.34 



