834 ME. J. H. coLLnrs o-n the stjdbtjey copper-deposits. 



49. On the Stjdbuey Coppee-Deposits. By J. H. Collins, Esq., 

 F.G.S. (Read June 6, 1888.) 



[Abridged.] 



The extensive deposits of copper-ore in the neighbourliood of Sud- 

 bury, to the north of Georgian Bay on Lake Huron, have attracted 

 a great deal of attention during the past two years. 



The geological and mineralogical characters of the Huronian 

 rocks of the Sudbury district were described by Prof. Bonney in a 

 paper read before the Geological Society of London in November of last 

 year *. The copper was discovered about the time of his visit ; but 

 as he does not refer to it in his paper, I presume his attention was 

 not called to it. At first it was thought to be an immensely 

 important discovery, likely to revolutionize the copper-trade, 

 and to reduce the price of copper, then, and for a long time 

 after, only <£40 per ton, to a figure which would render such mines 

 as Eio Tinto, Calumet and Hecla, and Anaconda quite unremunera- 

 tive. One of the deposits, the Stobie Mine, which had been 

 tested by a series of shallow trial pits, was reported to consist of 

 " a mass of solid sulphides of copper and iron, 1600 ft. long and 

 1200 ft. across," the depth being supposed practically unlimited. The 

 description (published only a few months before my visit in October 

 1887, but written some time before) runs accurately enough 

 as follows : — "It is in the form of a wide round hill, covered, like 

 the surrounding region, with burnt trees, and in appearance it does 

 not differ in any way from the other low hills around, except in 

 the presence of a large proportion of oxide of iron, which gives a 

 red appearance to the surface soil. Beneath this is a kind of 

 ' pan ' of iron oxide resembling bog iron-ore, and still deeper frag- 

 ments of partially decomposed pyrites " f. At first the ore- bodies 

 were supposed to be as extensive as these surface-gozzans, and as 

 similar gozzans may be traced at intervals for eight miles in a 

 south-westerly direction as far as Kelly Lake, nearly following the 

 strike of the rocks, the most exalted notions were entertained as to 

 the value of the deposits. 



The principal mine- workings are about eight miles apart. These 

 are known as the Copper Cliff and the Stobie respectively. Other 

 smaller works have been started and are known as McConnell, the 

 Eyre Mine, the Evans, the Lady Macdonald, and KeUy Lake. 



Copper was first discovered at a point on the main line about 

 two miles north-west of Sudbury in 1883, and the Canadian Copper 

 Company was formed to work the Copper Cliff and Stobie in 1885. 



At the former place the ore was found in the face of a cliff of 

 diorite forty or fifty feet high. By digging away at the foot of 

 this cliff a total height of 80 or 90 ft. was soon exposed. This was 

 thought to be a cutting in a veritable mountain of ore — decomposing 



* Quart. Journ. Geol. Soc. vol. xliv. p. 32. 

 * Canadian Miaing Review,' Sept. 1887. 



