480 



Canadian Record of Science. 



The atomic and quantivalent ratios deducible from the 

 above figures are as follows : — 



Quantivalent. 



Si 



Al 



Fe m 



Fe 11 



In 



Ca 



Ms 



595 



112 



296 



51 



11 



529 



9 



2380 

 336 



= 102 



} 



22 



\ 12 

 58 lZ 



18 J 



2380 

 1224 



2380 



2424 



This shows that the mineral is a unisilicate, and it 



ii in 

 agrees well with the garnet formula E 3 R 2 Si 3 12 , E being 



chiefly calcium and R chiefly ferric iron. Being, there- 

 fore, a lime -iron garnet, it should be referred to the 

 sub-species Andradite. 



2. DUNGANNON. 



Among the minerals in the Nepheline Syenite of Dun- 

 gannon, Ontario, 1 is a brown garnet, sometimes showing 

 crystalline form, but occurring for the most part in small 

 irregular grains. After careful separation by means of 

 dense liquids, the grains were found to have a specific 

 gravity of 3.739 and the following percentage composi- 

 tion : — 



Silica 36.604 



Titanium dioxide 1.078 



Alumina 9.771 



Ferric oxide 15.996 



Ferrous oxide 3.852 



Manganous oxide 1.301 



Lime 29.306 



Magnesia 1.384 



Water 285 



99.577 



1 See papers on this rock and some of the minerals which it contains, by Dr. Adams 

 and the writer, in the American Journal of Science, Vol. XLVIII., July, 1S94. 



