﻿186 Canadian Record of Science. 



nickel. The change is regular and gradual.^ Business- 

 considerations forbid the use of comparative figures, but 

 in general terms it may be said that a deposit which 

 shows large amounts of copper and small amounts of 

 nickel at the surface^ changes regularly with the depth tO' 

 a nearly equal ratio at the present time. The tendency 

 of copper and nickel to separate — the copper outward and 

 the nickel inward — seems also to increase with the depth. 

 Taking the copper as unity, and plotting the percentage of 

 nickel at each level as a factor thereof, the ratio of 

 the two metals will be shown to approach each other 

 as the depth increases. 



Comparing this Fig. 7 with Fig. 4A, it will be seen that 

 in the mattes the tendency is to change from a high 

 copper matte at the surface to matte carrying nearly 

 equal amounts of copper and nickel at about one-third the 

 depth of the pot, then a rapid decrease of copper and 

 increase of nickel near the centre, and a recovery to 

 nearly equal parts of copper and nickel at the bottom. In 

 the ore we cannot tell what proportion of the depth of the 

 deposit has been opened out, but there is, nevertheless, a 

 parallelism between the ratio of copper and nickel in the 

 ore as far as opened and the ratio of copper and nickel in 

 the upper half of the matte pot. 



From the behavior of copper-nickel mattes kept for 

 a long time in a molten condition, we have drawn the 

 inference that in proportion as the time of cooling is 

 prolonged, the more perfect is the separation of copper 

 and nickel into their respective sulphides. If the theory 

 of igneous origin be the correct explanation of the Sudbury 

 ore-bodies, it is evident that the upper and outer portions 

 of the deposit were the lirst to cool, while in the centre 

 and lower part of the deposit the sulphides have longer 

 remained fluid. If, then, a parallelism exists between the 

 ore and the matte, we would expect to find the separation 



1 Levat: Piogres de la Metallurgie du Nickel, p. 27. 



