244 THE ROYAL SOCIETY OF CANADA 



titaniferous and non-titaniferous magnetites, not now being worked^ 

 are associated with basic intrusives that appear to be of pre-Algoman 

 age. Arsenic occurs in two epochs and has been produced in economic 

 quantities from the rocks of both. In so far as is known, gold occurs 

 in economic quantity only in the Algoman, although small quantities 

 are obtained in refining the copper-nickel ores, and certain auriferous 

 quartz deposits, not now productive, appear to be genetically con- 

 nected with Keweenawan intrusives. Nickel, as has been shown 

 in the preceding table, was deposited in economic quantities in 

 two epochs. Cobalt, silver and copper are produced only from deposits 

 of Keweenawan age. Platinum, palladium, mercury and other 

 metals are found in small quantities with Keweenawan ores.^ Zinc 

 and lead have been mined in the Province, but the age relations 

 of some of the deposits are in doubt. 



The Keweenawan — The basic rocks that are classed as of 

 Keweenawan age are found in numerous localities as dykes, sills and 

 flows over a vast region in that part of the pro taxis occupied by Ontario, 

 Michigan and adjoining territory; in so far as can be determined 

 at present these rocks are also found far to the northeast in the former 

 territory of Ungava, now part of Quebec, and to the far northwest 

 in the Coppermine River basin and northward to the Arctic coast. 



In Michigan and in the Coppermine River country these basic 

 intrusives and extrusives are considered to be genetically connected 

 with deposits of native copper. In Ontario, along the north shore of 

 Lake Huron, the Keweenawan intrusives appear to have given rise to 

 the deposits of copper pyrites, while at Sudbury the copper-nickel 

 ores and at Cobalt the silver-cobalt veins have been shown to be 

 genetically connected with them. 



While it is not the intention in this paper to go into detailed 

 descriptions, there are a few facts relating to the ores that are geneti- 

 cally connected with the Keweenawan basic intrusives that should 

 be emphasized; viz.: (1) They contain the greatest known quantities 

 of the two magnetic metals cobalt and nickel, and a high percentage 

 of the third element iron; (2) The deposits are widespread. In 

 the region surrounding Cobalt, silver-cobalt veins are found here and 

 there over an area at least 5,000 square miles in extent. Beyond this 

 region cobalt ores are associated with these rocks in the township of 

 Otter, north of Lake Huron, and in small quantities along the shore 

 of the lake opposite Desbarats. Similar ores have been found on 



^At the present rate of production, (l915), the precious metal contents of the 

 Sudbury copper-nickel mattes will represent yearly probably at least 3,000 ounces 

 of gold, 110,000 of silver, 6,000 of platinum and 9,000 of palladium; but there is 

 loss in refining. 



