320 ROYAL SOCIETY OF CANADA 



acter of the dififerentiation is shown by a series of chemical analyses. 

 In the norite, hypersthene and enstatite usually predominate largely 

 over the diallage and the rock contains notable quantities of quartzite 

 sometimes in granophyric intergrowths with the basic plagioclase feld- 

 spar. Pyrrhotite, chalcopyrite and pyrite are always present in the 

 rock as original constituents and sometimes, in perfectly fresh specimens, 

 are so abundant that the rock might be classed as a pyrrhotite norite. 



The norite forms one large and several smaller masses, the latter 

 probably connected with the main mass at no very considerable depth. 

 The ore occurs at the margin of the norite intrusion in large, irre- 

 gular, oval-shaped masses. It consists mainly of pyrrhotite with smaller 

 amounts of chalcopyrite, etc. The nickel is present in the mineral 

 pentlandite which is distributed mainly through the pyrrhotite. All 

 the minerals found in the ores are described and their chemical com- 

 position discussed. The ores of igneous origin, the result of differen- 

 tiation, though secondary action has played a considerable role in 

 some instances. 



The report includes a review of the previous examinations and 

 descriptions of the district and a history of mining development in the 

 region ; discusses the origin and genesis of nickel ores throughout the 

 world ; the meitallurgical processes and the mode of refining the nickel 

 are described and the uses of nickel detailed. 



(4) Bell, J. M. — ^The rocks of the district are mapped as Keewatiu with the asso- 

 ciated iron formation separately coloured, Lower Huronian, post- 

 Huronian granites, etc., and Keweenawan eruptives. The Keewatin 

 schists form several extensive areas within which lie long, broken bands 

 of the iron formation. The Lower Huronian and Keweenawan erup- 

 tives form a number of, relatively, much smaller areas lying almost 

 entirely, within or on the borders of the Keewatin areas. The post- 

 Huronian granites and syenites occupy by far the greater part of the 

 district. The Keewatin schists are unconformably overlain by the 

 Lower Huronian, the post-Huronian granites, etc., are younger than 

 and have intrusive contacts with both of the preceding formations while 

 the basic Keweenawan eruptives are the youngest rocks of the district. 

 The Keewatin and Lower Huronian are folded and in one area the 

 Keewatin occurs in a closely folded synclinorium. 



The Keewatin is a complex of schistose rocks originally gabbro, 

 quartzite porphyry, felsite, tuff, etc., with isolated occurrences of phyl- 

 lite and arkose. These rocks are, in places, further altered to sericite 

 and chlorite schists, and sometimes to biotite and amphibole schists. 

 The iron formation of the Keewatin consists of cherts, jaspers and iron 

 oris interbanded with and grading into one another, quartzites and 

 phyllites also occur within this division. The Lower Huronian con- 

 sists chiefly of a closely folded and mashed conglomerate. The post- 

 Huronian acid intrusions include granite and syenite with quartzite 

 I)orphyry faciès. Certain areas of banded gneisses within the granites 

 are thought to be much metamorphosed Keewatin quartzite porphyry. 

 The Keeweenawan eruptives consist of diabase and gabbro in the form 

 of dykes, sheets and bosses. 



