228 Canadian Record of Science. 



examination which were apparently free from intermixed 

 impurities. They were creamy-white in colour, and were 

 found to have a specific gravity of 3-05. 1 An analysis made 

 in the college laboratory by Mr. Sidney Calvert, gave the 

 following results : — 



Silica 53-99 



Alumina 0*55 



Ferric Oxide 1 ■ 00 



Ferrous Oxide 10-99 



Manganous Oxide 2-19 



Lime 12-53 



Magnesia 16-25 



Loss on ignition 2-56 



100-06 



The atomic and quantivalent ratios deduced from the 

 above analysis are given below, and it will be seen that the 

 mineral is a true bisilicate. 



Atomic. Quantivalent. 



Si 899 x 4 = 3596 3596 2 



Al 10 x 3 = 30 1 



Fe '" . . . . 12 x 3 = 36 I 



Fe" .... 152 x 2 = 304' lftQ9 , 



Mn 31 x 2 = 62 f LOyJ 1 



Ca 224 x 2 = 448 | 



Mg 406 x 2 = 812 J 



It is interesting on account of the large proportion of 

 ferrous and manganous oxides which it contains, and differs 

 considerably in composition from the mountain cork of 

 Zillerthal, examined by Scbeerer. His analysis gave : — 



Silica 57-20 



Ferrous Oxide 4-37 



Lime 13-39 



Magnesia 22 85 



Loss on ignition 2-43 



100-24 



1 Dry fragments float upon water for a time, owing to the air 

 which they contain. In determining the specific gravity, the air 

 was got rid of by soaking under water in vacuo. 



