ADAMS A barlow] ALKALI SYENITES OF EASTERN ONTARIO 37 



its usual optical properties. It frequently holds rounded inclusions of 

 albite and of ealcite. The albite is well twinned and possesses the usual 

 characters. The hornblende is the most abundant constituent, and, if 

 not hastingsite, is a variety closely resembling it. It is deep green in 

 colour, looks black on the fractured surface of the rock. Although the 

 rock is so basic, it contains no iron ore, which is elsewhere common as 

 ani accessory constituent in such rocks. The ealcite, as usual occurs as 

 rounded inclusions in the albite, nepheline or hornblende, or filling 

 spaces between the grains of these minerals. No microcline nor micro- 

 perthite is present in the sections. 



Analysis of the rock by Prof. Norton-Evans shows it to have the 

 following composition : — 



SiO^ •. . . . 43.67 per cent. - 



TiO, .78 



AI263 20.91 



FcgOs 3.54 



FeO 8.01 



MnO .05 



CaO 7.37 



MgO 1.46 



K2O 2.25 



Na.0 6.73 



PÀ .11 " 



CO2 2.37 



H,0 2.52 



99.77 

 ^J'he norm of the rock will then be as follows: — 



Orthoclase 12.79 per cent. 



Albite 22.01 



Anorthite 20.29 '' 



Nepheline 19.03 



Olivine 10.58 



Ilmenite 1.52 



Magnetite 5.10 



Apatite .34 " 



Calcite 5.41 " 



97.07 

 Water 2.53 



; 99.59 



