136 K. BELL NICKEL AND COPPER DEPOSITS OP SUDBURY. 



the same temperature, they would naturally accompany each other when in 

 the fluid condition. The bodies of molten diorite, being large, would remain 

 fluid for a sufficient time to alloAV the diffused sulphuretted metals to gather 

 themselves together at certain centers by their mutual attractions and by 

 concretionary action. In the case of great irrupted masses of diorite, the 

 bodies of ore which had formed near enough to the solid walls cooled and 

 lodged with a mixture of the broken wall-rocks wdiere we now And them, 

 while larger quantities, remaining fluid, probably sank slowly back through 

 the liquid diorite to unknown depths. The causes which, at a subsequent 

 time, favored the production of transverse dikes probably aided in determin- 

 ing the deposition of the ore near certain lines rather than elsewhere. 



If we suppose that the molten sulphides abstracted themselves, by the laws 

 of mutual attraction, from the general mass of the fluid rock and got together 

 in considerable quantities in an intimately mingled form, the two kinds 

 would tend by the same laws to separate themselves from one another, like 

 going to like, just as salts of different kinds will separate into their respective 

 crystals from an aqueous solution, because there is analogous action between 

 mixtures liquefied by heat and by solution in a supersaturated menstruum. 

 A study of the relations of the pyrrhotite and chalcopyrite to each other in 

 these mixed ores and of the ores of the parent rock shows that this view is 

 in accordance with the facts, and that it is probably a satisfactory explana- 

 tion of the phenomena. No theory of aqueous deposition apjfears to account 

 for the facts in connection with these ore bodies ; still we do occasionally 

 observe limited local modifications of the ore which may have been due to 

 the solvent action of water with subsequent precipitation of mineral matters 

 long after the consolidation of the mass. This is more particularly the case 

 with regard to the chalcopyrite. Crystals of quartz and of the felspars and 

 rarely of apatite are found embedded in the ore. 



Extent and Associations of the Ores. 



Other metals, including gold, platinum, tin, lead, silver, zinc and iron, have 

 been found in the Sudbury district, and probably some of them may prove 

 to exist there in paying quantities. The presence of a considerable propor- 

 tion of nickel in the ore of the Wallace mine, on the shore of Lake Huron 

 and in the strike of the Sudbury deposits, was ascertained by Dr. Hunt 

 more than forty years ago ; yet the presence of this metal in the latter does 

 not seem to have been suspected for a considerable time after they had been 

 worked for copper alone. The Huronian is notably a copper-bearing sys- 

 tem. West of Sudbury, in the great belt we have already traced, this metal 

 occurs around Batchawana bay, north of Sault Ste. Marie, at Little Lake 

 George and Echo lake, at Huron Copper bay, in Wellington and Bruce mines? 



