On the origin and relations of the nickel and copper deposits of Sudbury, Ontario, Canada
Economic Geology and The Bulletin of the Society of Economic Geologists
The ore bodies with which the nickel and copper are immediately associated consist essentially of pyrrhotite' (mostly FesS9), which is the predominant constituent, and chalcopyrite (CuFeS,.) usually in much smaller amounts. It has been conclusively proved by means of the magnetic experiments carried on by Brown, 2 Dickson s and the writer, 4 that the nickel present in these ore bodies is not, as so many have supposed, an essential constituent of the pyrrhotite, isomorphously replacing an
... replacing an equivalent amount of the iron, but is mainly present as a distinct and magnetically separable nickel-iron-sulphide known as pentlandite ( (Ni 4-Fe)S). This pentlandite is usually very finely and uniformly distributed throughout the whole mass, although in certain mines, as the Creighton, Copper Cliff, Evans, and, very noticeably, the Worthington mine, it occurs in spots and patches, often as much as half an inch to an inch or even more in diameter of fairly pure material. The relative abundance of this nickel-iron-sulphide determines the richness, or otherwise, of the containing deposit. Pyrite also occasionally contributes to the formation of these deposits, and much of it is nickeliferous. Present opinion varies somewhat in regard to the form in which the nickel is present in this compound, Dr. Walker's o researches tending to prove • Published by permission of the Director of the Geological Survey of Canada.