S. L. Penfield — Pentlandite from Sudbury, Out. 495 



a sulphide from the Worthington Mine, on the Algoma Branch 

 of the Canadian Pacific Railroad, about 30 miles southwest of 

 Sudbury. To this mineral he has given the name folgerite. 

 From his description and the analyses it is evident that folger- 

 ite is identical with the pentlandite just described. His dis- 

 cription of the physical properties agrees fairly well. "A 

 fragment associated with adhering pyrrhotite showed a sp. gr. 

 of 4*73 " while that of pentlandite is 5 - 00. "Form, massive, 

 with a platy structure. No crystals have as yet been observed." 

 This description of the platy structure corresponds to some 

 specimens of pentlandite which were seen at the laboratory of 

 the late Prof. F. A. Genth, only a few weeks before his death. 

 He was about to examine the mineral and had obtained speci- 

 mens of the Sudbury ores from the Canadian Geological Sur- 

 vey. His material was much better than that examined by the 

 author, in that it showed larger patches of the pentlandite in 

 the pyrrhotite. The octahedral parting, developed especially 

 in one direction, gave the platy structure noted by Dr. 

 Emmens. A most remarkable statement by Dr. Emmens can 

 not be readily understood. " Magnetism — In large fragments 

 the mineral is non-magnetic. In minute grains it is magnetic. 

 The finely triturated powder is non-magnetic." The formula 

 proposed for this mineral is !SliFeS 2 deduced from the follow- 

 ing analyses by Mr. C. T. Mixer, in all of which the sulphur 

 was determined by difference. One direct determination of 

 sulphur in a fourth sample gave 34 per cent. 



A 



Ni 35-20 



Fe 33-70 



S 31-10 



B 



C 



Calculated 

 for NiFeSo 



31-45 



29-78 



32-87 



31-01 



26-89 



31-30 



37-54 



43-33 



35-83 



100-00 100-00 100-00 100-00 



It is evident that the above are all analyses of pentlandite or 

 of some mixture in which it predominates. They differ from the 

 analyses of the pentlandite from Lillehammer chiefly in the rela- 

 tive proportion of iron and nickel, which, being isomorphous, 

 may replace one another through a wide range. The agree- 

 ment between the separate analyses and theory is far from 

 satisfactory and certainly for the establishment of a new 

 mineral species a direct determination of the important con- 

 stituent, sulphur, should have been made. There is, there- 

 fore, no sufficient ground for making a new species of this 

 mineral and it is to be hoped that folgerite will never find a 

 place in mineral ogical literature. 



