﻿Segregation in Ores and Mattes. 189 



enclosures, and that by gradual cooling the diorite 

 was first separated, then the copper as copper pyrites, and 

 the iron as pyrrhotite containing some nickel, and, finally, 

 in those portions remaining longest molten the nickel 

 separated as a true nickel mineral. While this view may 

 be at variance with the theories of many authorities, yet 

 it seems to be the only conclusion feasible in view of the 

 similarity in the manner of segregation of the elements in 

 copper-nickel ores and mattes. 



Appended Note to the Paper^ of Mr. Browne. 



By J. F. Kemp. 



That the reactions of metallurgical processes have 

 served to throw much light on the problems of igneous 

 rocks has long been recognized, and from the observations 

 of J. H. L. Vogt, and others, on slags and the artificial 

 minerals yielded by them, important inferences have been 

 drawn regarding rocks. This source of evidence is a 

 fruitful and suggestive one, for, although on a small scale 

 when compared with volcanic phenomena, the parallelism, 

 so far as it goes, is close — the principal difference being 

 that slags cool quickly, under slight pressure and without 

 the presence of mineralizers. The advantages are that 

 the reactions are under observation, and all the factors 

 can be noted. 



Late developments in the mining of associated nickel 

 and copper ores, and attempts both recent and early 

 to utilize titaniferous magnetites have exposed such 

 geological relations that many observers have felt 

 compelled to regard the ores themselves as of igneous 

 origin. They occur in rocks of this original character, 

 and ores that show small evidence of any geological 

 disturbance. In the case of the associated sulphides of 

 nickel and copper, the occurrence of the ores in the outer 

 portions of the intrusions has been the chief argument 



1 This note is added with the full sanction of Mr. Browne. 



