752 E. GILPIN ON SOME RECENT DISCOYEE1ES 



the micaceous ore has been to some extent replaced by carbonate of 

 iron, which is the chief gangue of the Polson's-Lake ore. 



The sixth vein is gradually returning to its east-and-west course ; 

 and at a further distance of 300 yards it has been opened again, and 

 proved to be 4 feet 6 inches wide ; and nearly half a mile to the 

 east, on the strike of the vein, two small veins have been found 

 holding very good ore, and large boulders proving the passage of the 

 larger veins. 



The course of the cupriferous band has been traced, by surface- 

 indications, from this point, about four miles, to Poison's Lake, 

 where, during the past summer, a very fine vein of spathic ore, 

 holding copper-pyrites and a little iron-pyrites, was traced for several 

 hundred feet through dark blue and olive slates. Its width varied 

 from 6 to 11 feet ; and its course was about N. 70° W. (astr.). Dr. 

 Dawson gives the average of copper in this ore at 10-8 per cent. ; I 

 should judge from samples shown me that it is considerably higher. 



The age of the strata holding these deposits is not yet clearly 

 settled. Dr. Honeyman, in a Geological Report to the Provincial 

 Government, stated that the Poison's- and Lochaber-Lake strata 

 were of Devonian age. 



Prom following the line joining the copper and iron districts, it 

 will at once appear, on mapping the exposures and strikes, that 

 these measures are on the same geological horizon as those holding 

 the limonite and micaceous ores of the East and Middle Rivers of 

 Pictou. 



These latter measures, both at the East River of Pictou and at 

 the Cobequids, are overlain by strata of Lower-Helderberg age. 

 On the other hand they are readily referred to a later age than the 

 auriferous rocks of the Atlantic coast. jSo fossils have yet been 

 found clearly defining their position ; and, in the absence of a reliable 

 geological survey, they may be provisionally considered as rilling a 

 place near the middle of the Silurian strata. 



The metamorphism of this range of iron- and copper-bearing 

 strata would appear to have taken place before the commencement 

 of the Lower Carboniferous epoch ; for we find conglomerates and 

 shales of that age deposited around diorite dykes on the East River, 

 and the former holding pebbles identical with the ore-bearing slates. 

 The date of the filling of the fissures with ores does not appear 

 equally certain ; for the Lower Carboniferous sandstones and lime- 

 stones, which in places overlie the ore-strata, frequently contain small 

 veins of specular ore, which, with magnetite, also occurs in the 

 fissures of the Triassic trap. 



The quality of the Lochaber ore is unusually good ; the chief 

 variety met is copper pyrites with a small admixture of carbonate 

 of copper and embescite. The gangue at Lochaber is chiefly mica- 

 ceous iron-ore, with a little spathic ore ; at Poison's Lake exclusively 

 the latter, which yielded on assay 35 per cent, of iron. 



An average of the large veins gave, on analysis by Dr. How, of 

 "Windsor : — • 



