418 W. O. Foye — Nephelite Syenites of Ontario. 



The biotite is nearly black in color. 



The albite corresponds to the mixture (Ab 96 An 4 ). 



The calcite occurs as rounded grains between the other 

 minerals. It is evidently primary in origin. 



The microcline is closely associated with the nephelite and 

 occurs also as resorbed blebs in the albite. The evidence 

 points to the fact that the earlier found microcline was unstable 

 and that the increasing amount of soda in the magma allowed 

 albite to take its place. 



The rock is hypidiomorphic, sometimes poikilitic, in texture. 



Chemical composition. — No chemical analysis of the par- 

 ticular rock described above is available. This rock is, how- 

 ever, practically the same as one described by Adams and 

 Barlow* from the adjacent township of Monmouth. The 

 analysis of the latter rock is as follows : — 



Si0 2 



51*58 per cent 



The calculated 



norm is : — 



TiO, 



•35 



Orthoclase 



25*02 per cent 



AlA 



19-40 



Albite 



38-84 



FeA 



4-26 



Anorthite 



6-67 



FeO 



5-29 



Nephelite 



15-50 



MgO 



•49 



Diopside 



•90 



MnO 



•20 



Olivine 



5'05 



CaO 



3-64 



Ilmenite 



•73 



Na 2 



7-49 



Magnetite 



6-15 



K,0 



4-23 



Apatite 



•34 



PA 



•15 



Calcite 



3-45 



co 2 



1-53 



Water 



1-02 



H,0 



1-02 





QQ-«*7 



99-59 



The rock occupies, the following position in the " norm " 

 classification : 



Class II .Dosalane 



Order 6 Nogare 



Rang 2.. Essexase 



Sub-rang 4 Essexose 



3. Nephelite Pegmatite. 



Macroscopic description. — Nephelite in irregular, anhedral 

 crystals 4-5 cm. long and 3 cm. wide composes the larger portion 

 of the nephelite pegmatite. Masses of calcite which show part- 

 ing on -4; R are found between the nephelite crystals. A few 



*F. D. Adams and A. E. Barlow, Memoir No. 6, Canada Geol. Surv. 

 1910, pp. 262-264. 



