62 



Nickel 41.96 



Iron 15.57 



Silica 1.02 



Copper 62 



Sulphur 40.80 



These figures give approximately the formula Ni^ Fe S^. Neither 

 cobalt nor arsenic could be detected. If we deduct silica together with 

 the copper reckoned as admixed chalcopyrite and re-calculate the 

 remainder of the analysis to 100% we get the following figures : — 



Nickel 43-i8 



Iron 15.47 



Sulphur 41-35 



In short the mineral has the composition of Ni4 S5 with about 

 ^th of the nickel replaced by iron, which seems to agree with Laspeyres 

 polydymite of which it is doubtless a ferriferous variety. Probably in 

 most cases the niccoliferous constituent of pyrrhotite is millerite, but 

 other sulphides like polydymite may occur too. The polydymite which 

 was selected for the above analysis came from the mass in which the 

 average of 35.39 % nickel and 5.20 % copper had previously been 

 found. 



The mass weighed several kilograms and was remarkably free from 

 quartz. The same mass, with two smaller pieces resembling it, were 

 also examined for platinum. The results were as follows, "A" repre- 

 senting the large mass in which the polydymite was determined : — 



A. . . . 2.55 oz. platinum per ton, or .0087 °l^ 

 B.... 1.80Z. " " " .0060% 



C . . . . 7 oz. " " " .024 % 



Probably the platinum exists in the ore as sperrylite, although this 

 point was not proved. The amount of platinum in the mass most 

 thoroughly examined would require to form sperrylite only abou^ 

 .007 7o o^ arsenic, which is too small a quantity for detection by ordin- 

 ary analysis. That platinum should exist in appreciable quantities in 

 an ore of such a character is something quite extraordinary, but 

 whether it could be profitably extracted is an open question. Sperry- 



