Dickson — Platinum in the Nickel- Copper Ores. 137 



Akt. XI. — Note of the Condition of Platinum in the Nickel- 

 Copper Ores from Sudbury ; by Chas. W. Dickson.* 



The determination of the new mineral sperrjlite (PtAs a ) by 

 Professors Penfield and Wells, in 1889, f has led to a great deal of 

 speculation since, as to the condition of platinum in various ores 

 where it is known to occur. This applies especially to the nickel- 

 copper ores of the Sudbury District, Ont., in which a small per- 

 centage of the platinum metals seems to be always present. 



As originally discovered by Mr. F. L. S perry, the sperrylite 

 occurred in the loose gossan material, which consisted of gravel 

 containing iron and copper oxides and sulphides, and which 

 was found near a quartz vein at the Vermilion mine in Algoma, 

 Ontario. In 1896, T. L. Walker % made some further investi- 

 gations on this gossan from the Vermilion mine, and decided 

 that the sperrylite occurred in connection with the chalcopyrite, 

 while none could be detected associated with the fragments of 

 pyrrhotite. Summing up, he says : " In this connection it may 

 be mentioned that in all the copper-nickel mines of the Sud- 

 bury District traces of the metals of the platinum group are 

 found, and also that the nickel matte from mines low in cop- 

 per contains very little platinum, while mines richer in copper 

 afford a matte proportionately richer in platinum. In short, 

 the platinum contents of the nickel matte in the Sudbury Dis- 

 trict is directly proportional to the copper contents ; viz., 

 proportional to the amount of copper pyrites in the original 

 ore. This fact, taken in connection with the detection of 

 sperrylite in fragments of chalcopyrite, while a careful search 

 did not reveal it in the pyrrhotite fragments, renders it very 

 probable that the platinum found in the Sudbury District in 

 the copper-nickel mines in general occurs as sperrylite, and 

 that the mineral occurs generally, if not exclusively, in chalco- 

 pyrite." Thus, while the opinion has been quite general that 

 the platinum in the unaltered ores of the nickel-copper mines 

 of the Sudbury District was in the form of the arsenide, the 

 matter was not proved directly, and the conviction was inferred 

 only from analogy with the occurrence at the Vermilion mine. 



Professor Vogt has recently § published the results of a 

 number of analyses of various ores from the Norwegian nickel- 

 iferous pyrrhotite deposits. He finds that a small but appreci- 

 able quantity of the metals of the platinum group is always 

 present. The copper minerals, as in the Canadian occurrences, 

 contain the largest amount. His opinion is that the platinum 

 is present as sperrylite, connected with the chalcopyrite ; but 

 this has not as yet been proved, though the results obtained in 



* 1851 Exhibition Scholar, from Queen's University, Kingston, Ont. 



f This Journal (3) xxxvii, pp. 67, 71, 1889. \ This Journal (4), i, p. 110, 1896. 



^ " Platingehalt in norwegischen nickelerz.", Ziet. fur prak. Geol., Aug. 1902. 



Am. Jour. Sci.— Fourth Series, Vol. XV, No. 86.— February, 1903. 

 10 



