﻿Segregation in Ores and Mattes. 



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I I I I I 



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If we now examine the Sudbury ore-deposits, a general 



Fig. 4a. resemblance in their for- 



~i I I '""1 ' I I ' ' rn mation to the formation of 



_ mineral in mattes may be 



- readily seen. The ten- 

 ~ dency of copper pyrites to 

 _ separate from the nickeli- 



- ferous pyrrhotite is very 

 ~ noticeable. However close- 



- ly the two minerals may 

 ~ be intermingled, each is 

 _ entirely free from traces of 



- the other. The chalcopy- 

 ". rite is free from nickel, 



while the pyrrhotite beside 



I" v< V "^ "« 5 ^ i^ is equally free from 



Central vertical line of matte. COppCr. Bcsidc this chcmi- 



The per cent, copper taken as 100. ^ ^ 



Vertical lines distance from top. Horizontal Cal Separation, there IS an 



= variation of nickel. equally noticcable .physical 



separation. BelP Kemp^ and others have remarked the ten- 

 dency of copper pyrites to separate in veins or stringers of 

 ore surrounding masses of included diorite. It may be 

 stated, as a rule, that copper tends toward the rock, 

 whether forming the vein-walls or forming included 

 masses. The miners often remark the way in which 

 copper follows the rock, and look on the presence of 

 massive copper ore as indicating an approach to the rock. 

 In driving a drift from the shaft which is sunk in the 

 clean diorite to and through the ore, the first symptoms 

 of the presence of the vein are small shots or pockets 

 of copper pyrites impregnating the rock. Coming nearer 

 to the ore-body, the amount of copper increases,^, large 

 masses being met with before any nickel is found. On 

 reaching the ore-vein proper, the copper pyrites is found 



1 Report on Sudbury Mining District, 1888-90, p. 49. 



2 Ore-Deposits of the United States, p. 319. 

 3 -Peters: Modern Copper Smelting, p. 291. 



