302 MINERALS AND GEOLOGY 



and copper pyrites in the Keweenian formation of Black Bay (Enter- 

 prise mine), the author found a small percentage of gold, averaging 

 about 18 dwts. in the ton of ore. 



Silver: Nearly all the pyritous veins of this district hold small quan- 

 tities of silver, more especially when the vein-matter carries intermixed 

 copper pyrites, iron pyrites, zinc blende and galena; but paying 

 amounts are confined almost wholly to the calc-spar (or calc-spar and 

 quartz) veins around or in the vicinity of Thunder Bay. These veins 

 traverse, as a rule, the black slates of the Animikie formation, but 

 some occur in the Keweenian series. The most remarkable of these 

 veins is that which runs through Silver Islet, a small rock lying a 

 few miles east of Thunder Cape, where the slate is in contact with a 

 comparatively broad and persistent dyke of sub-crystalline diorite. 

 The vein cuts this transversely and carries native silver, silver glance 

 and galena, with subordinate shews of pyrites, blende, plumbago, &c., 

 in a gangue of calcite mixed in places with quartz and a little fluor- 

 spar. Although now abandoned, the vein has yielded an amount of 

 ore (mostly native silver) valued at the lowest estimate at more than 

 three millions of dollars. The workings extended far under the level 

 of the lake ; and when the mine was closed in 1884 its shaft had 

 been carried down to a depth of 1,230 feet. Other silver-bearing 

 veins traverse the Animikie formation immediately north and west 

 of Thunder Bay. Many of these have shewn very rich bunches of 

 ore, and several, comprising more especially the Rabbit Mountain., 

 Beaver Mountain, Badger, and Silver Mountain veins, are now being 

 successfully worked. A good deal of work has also been done on 

 the Shuniah or Duncan vein, but the work on this vein is now 

 stopped for a time. Other mining locations in this neighborhood, on 

 most of which, however, merely trial pits have been sunk, comprise 

 the Silver Creek, Singleton, Porcupine, Crown Point, Spar Island, and 

 other properties. Silver-bearing veins are also known on Pie Island 

 in Thunder Bay. The gold-bearing veins of the Shebandowan district 

 and the Lake of the Woods are likewise more or less argentiferous.* 

 Many of the Huronian copper ores of Sudbury also hold small 

 amounts of silver ; and a vein of argentiferous galena (some portions 

 of which hold over 100 oz. of silver in the ton) has been worked, off 



* In some of the Shebandowan ores the presence of tellurium was first detected by 

 Dr. W. H. Ellis of the School of Practical Science, Toronto. 



