Titaniferous Andradite from Ontario. 213 



Silica 34-184 



Titanium dioxide ___ 1*527 



Alumina .- 11*517 



Ferric oxide 12*621 



Ferrous oxide 21*979 



Manganous oxide *629 



Lime 9*867 



Magnesia -- 1353 



Potash 2*286 



Soda -- 3*290 



Water* -348 



99*601 

 Specific gravity . _ 3 *433 



The atomic and quantivalent ratios deducible from the above 

 inalysis are as follows : 



Atomic. Quantivalent. 



Si-- - 570X4 = 2280 ) 



Ti 19X4= 76 f 2356 235b 



1 152 ^ 



Al 226X3= 678 \ 



Fe m 158X3= 474 \ 



Fe 11 305X2= 610 . ' 



Mn ... 9X2= 18 p 354 



Ca_. 176X2= 352 ' 



Mg 34X2= 68 fLMJ 



K 48 48 



Na 106 106 



The ratio of (K a O+EO) : R 2 3 : SiO, is 601 : 192.* 589, or 

 approximately 3:1:3, and obviously the mineral is a true 



orthosilicate agreeing fairly with the formula (R a R) 3 R 2 Si 8 0, a , 

 or, more fully, (Fe, In, Ca, Mg, K 2 , Na 2 ) 3 (Fe, Al), (Si, Ti), M 

 — a constitution analogous to that of garnet. 



So far as we are aware no other hornblende containing so 

 small a proportion of silica has been analyzed ; but the small 

 percentage of silica is explained by the large proportions of 

 ferrous and ferric oxides. This is made plain by the following 

 formulae and the corresponding percentages of silica deduced 

 from them : 



Formula. P. C. of Si0 2 . 

 3FeO, Fe 2 3 , 3Si0 2 32*19 



3CaO, Fe 2 3 , 3Si0 2 35-43 



3FeO, A1 2 3 , 3Si0 2 36*14 



3Na 2 0, A1 2 3 , 3Si0 2 38-38 



3CaO, A1 2 3 , 3Si0 2 40-00 



*Loss after igniting for about fifteen minutes. On further ignition the powder 

 gained in weight owing to oxidation of the ferrous oxide. 



