The M outer egian Hills. 235 



correct, namely 440 per cent. — and this, of course, 

 includes both the unaltered mineral and that filled with 

 decomposition products — then 1.84 per cent, of the 

 kaolin has been derived from the alteration of the 

 nepheline. There will thus remain 3.12 per cent, of the 

 kaolin which has been derived from and measured up with 

 the feldspar. If this amount be added to the feldspar found 

 by calculation, it will increase the proportion present to 

 77.15 per cent., which is within 0.09 per cent, of the 

 percentage of feldspar obtained by the Eosiwal measure- 

 ment. 



The norm of the pulaskite is found to be as follows : 



Albite 

 Anorthite 

 Orthoclase - 



50.30) 

 - 9.73 [85.61 

 25.58) 



Nepheline 



„,. . f2MgO.SiO, - 

 01lvlne {2FeO-Si0 2 " - 



2.56 



203 \ 2 

 - 0.51J Zb ^ 



Corundum - 



0.41 



Magnetite - 

 Ilmenite - 



2.55 

 3.80 



Apatite - - - - 

 Water 



1.34 

 1.03 



99.84 

 Its position is, therefore, as follows : 



Class I, persalane. 

 Order 5, eanadare. 

 Rang 2, pulaskase. 

 Subrang 4, laurvikose. 



It should thus be termed a grano-laurvikose, or possibly, 

 in view of its somewhat poryphyritic structure, a grano- 

 phyro-laurvikose. The proportions of the several minerals 

 present, or mode, as determined by Kosiwal's method were 

 as follows : 



