72 



ROYAL SOCIETY OF CANADA 



An examination of these analyses will show at a glance the remark- 

 able similarity in chemical composition of these corundum-bearing rocks, 

 occurring at such widely separated localities as Canada and Russia. 

 The specimens of the Canadian and Russian occurrences are practically 

 identical. Xo analysis of the corundum syenite from India is avail- 

 able. The analysis of the feldspar from the Indian rock is very closely 

 analogous in composition to that of the other syenites free from corun- 

 dum, the only substantial difference being in the relative amounts of 

 soda and potash present. Taking into consideration the molecular values 

 of soda and potash, the ratio of the soda to the potash in the Indian felds- 

 spar is 5 :1, while in the Canadian and Russian occurrences the soda is 

 only slightly in excess, and in the separated feldspar is practically the 

 same. 



The following are the molecular ratios in the corundum syenites as 

 above : — 



CaO + K,0 

 Analysis I (a) = 1 



Analysis II (a) = 1 



Analysis III (a)^^ 1 



Na.,0 



ALO, : SiO, 



1 : 5.2 = Ontario 

 1.1 : 55 = Russia 

 1.1 : 5.9 =. Russia 



Mr. M. F. Connor, B. Sc, has also made analyses of the brown 

 corundum and the magnetite which are present in the syenite pegmatite. 

 These are given under I and II respectively. The material in both cases 

 was selected as free as possible from impurities or alteration products. 



The occurrence of the corundum in association with absolutely fresh 

 and unaltered minerals, in rocks of undoubted igneous origin and 



