ÔO ROYAL SOCIETY OF CANADA 



turbid from incipient alteration. Only occasional very small scales of 

 biotite were noticed and still more rarely small grains of magnetite. 

 The corundum in the thin sections consists of irregular shaped ap- 

 parently corroded individuals embedded in plates and scales of muscovite. 

 An analysis of the nepheline rich variety by Mr. M. F. Connor, 

 B.Sc, of the Geological Survey, shows it to have the following com- 

 position : — 



SiOa 48.38 



TiO, trace 



AI263 30.54 



FeA 0.40 



FeO O.OG 



MnO trace 



CuO trace 



CaO. 1.87 



MgO 0.19 



K2O 3.70 



Na,0 13.94 



P2O5 trace 



CO2 0.62 



H,0 0.50 



100.30 



If 1^8 norm of this rock be calculated, it will be found to be as 

 follows : — 



Orthoclase 21.68 



Albite 10.48 



Anorthite 5.56 



Nepheline 57.94 



Corundum 1.63 



Calcite 1.43 



Hematite 40 



Fosterite 35 



99.46 

 Water .50 



99.96 



