106 



THE ROYAL SOCIETY OF CANADA 



The veins occur under rather different conditions in the different 

 rocks of the district. As a general rule the vein-walls are sharply de- 

 fined. In a few places one or other of the walls is marked by a fault, 

 but this did not appear to be a general condition. 



In some places, where the adjoining rocks are schistose, veins 

 may occur as an imbricating series of short, apparently disconnected, 

 lenses, such as might be formed in fissures caused by torsional or diag- 

 onal strains exerted on the rock. In other places, where the rocks are 

 more massive, they occur in fissures or planes of jointage or shrinkage, 

 and in such cases they may run straight for a certain distance and then 

 may turn off sharply at the intersection of two jointage planes. 



In the vicinity of many of the veins the wall rock has been some- 

 what altered by the introduction of secondary minerals such as 

 quartz, tourmaline and calcite, but considered generally, the veins would 

 appear to have been largely formed by solutions ascending in open 

 fissures and depositing their load of quartz, etc., between the previously 

 formed walls of those fissures, rather than by a metasomatic replace- 

 ment of the walls of narrow fissures by quartz and its associated min- 

 erals. 



X X X X X XX 

 X^X X X X X XX 



Co curse^ X 



_. X X X X X XX 



X X X X 



X X 



X X 



X X 



X X 



X X 



XXX 



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Fig. 1. Granite dyke running into quartz vein, Kitchigamini Claim. 



Dr. Coleman states that the gold-bearing veins occur for the most 

 part in the quartz-porphyries and sericite schists, but my experience 

 was that many of them were in the zone of contact near the borders 

 of later granitic or dioritic intrusive masses. At Mackay Point on 

 Wawa Lake they occur in irregular fractures in a coarse, dark, quartz- 

 diorite not far from the contact with a fine-grained quartzose schist. 

 At the Hornblende Claim the country rock is a biotite schist. At the 



