408 MINERALS FROM LAKE SUPERIOR. 



and the geological position of the rock, immediately above that of the 

 Huronian strata, is in a measure identical with the horizon of the gold- 

 bearing rocks from -which the auriferous deposits of Eastern Canada 

 have been derived. No gold has hitherto been met with, however, in 

 the sands of the Kaministiquia or other streams of Thunder Bay. 



2. Galena, PbS. — This well-known mineral, the common ore of 

 lead, occurs at numerous localities on the north shore of Lake Supe- 

 rior. Some especially rich lodes lie in the township of Neebing, on 

 Thunder Bay, and others of even greater promise have been discovered 

 in the district around Black Bay. In most localities of this region, 

 the galena is accompanied by copper pyrites, the latter occasionally 

 predominating. The veinstone is principally quartz, with calc spar, 

 heavy spar, and fluor-spar in subordinate quantities. When crystal- 

 lized, the galena presents almost invariably the common combination 

 of cube and octahedron. This combination and the simple cube are 

 the only crystals that have come under my observation in these lodes. 

 I have assayed a good many samples for silver, without finding any 

 workable quantity of the latter metal. The highest amount that I 

 Lave obtained, corresponds, indeed, to no more than \\ oz. to the ton 

 of reduced lead. This comparative absence of silver appears to be 

 connected with the very general absence of arsenical minerals through- 

 out the district. I am not aware that attention has hitherto been 

 directed to this point ; but a comparative study of the classical lead 

 districts of both Europe and this continent will, I think, be found to 

 warrant the conclusion, that, where arsenical ores — such as arsenical 

 pyrites, Fahl-ores, &c. — are generally absent, the galena will not prove 

 to be argentiferous in a paying point of view. 



3. Marcasite, FeS^. — The occurrence, in Canada, of Iron Pyrites 

 in its Trimetric or Khombic condition, has not been hitherto an- 

 nounced. I obtained several well-characterised examples from the 

 walls of a large vein, holding galena and copper pyrites, in lot 25 of 

 the fifth concession of the township of Neebing, a few miles east of 

 the Kaministiquia river ; and a remarkably fine specimen from the 

 same locality was kindly presented to me by Mr. Mclntyre, of Fort 

 William. The latter specimen may be seen in the Museum of the 

 Toronto University. In all of these examples, tabular prismatic crys- 

 tals are united somewhat irregularly, but with the basal plane in com- 

 mon, in curved rows, with an acute angle of the prism projecting out- 

 wards, and thus forming the variety known as " Cockscomb Pyrites," 



