Sudbury Copper Deposits [Canada). 235 



June 7.— W. T. Blanford, LL.D., F.R.S., President, in the Chair. 



The following communications were read : — 



1. The following letter from H.M. Secretary of State for India 

 accompanying some specimens of rubies in the matrix fromBurmah: — 



India Office, WbitebaU, S.W. 

 Sie,— 2nd June, 1888. 



I am directed by the Secretary of State for India in Council) 

 to present to the Geological Society some specimens of Burmese 

 rubies attached to their matrix, which were procured by Mr. Bar- 

 rington Brown, at present employed by Government in examining 

 the mines which came into their possession on the annexation of 

 Upper Burmah. 



Mr. Barrington Brown writes concerning these specimens thus : — 

 " I send * * six specimens of rubies in granular limestone, where 

 they were formed. They were obtained by blasting, under my 

 direction, in a place formerly mined by natives * * * *. As I 

 believe the fact of the ruby being traced to its matrix is new to 

 science, the specimens may prove of interest to scientific men * * *. 

 I should like Professor Judd, President of the Geological Society, to 

 see the specimens." I am, Sir, 



Your obedient Servant, 

 Professor Judd, (Signed) J. A. GoDLEY. 



President, Geological Society. 



2. "On the Sudbury Copper Deposits (Canada)." By J. H. 

 Collins, Esq., F.G.S. 



These deposits occur in Huronian rocks. The author described two 

 exposures, known as Copper Cliff and Stobie, about 8 miles apart. 

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

 about 40 ft. high. 



The ore exists in three distinct forms : — 



1. As local impregnations of siliceous and felspathic beds of 

 clastic origin, in the form of patches and strings of cupreous 

 pyrrhotite. 



2. As contact-deposits of the same material lying between 

 the impregnated beds and large masses of diorite. 



3. As segregated veins of chalcopyrite and of nickeliferous 

 pyrrhotite, filling fissures and shrinkage-cracks in the ore- 

 masses of the second class. 



The author considered the first as original, or of high antiquity ; 

 whilst the two latter are due to segregation produced either by intru- 

 sion of diorite, or by internal movements. He compared these deposits 

 with those of Rio Tinto of Devonian age, showing their similarities and 

 differences. At the latter place the intrusive masses are quartz- 

 porphyries, and the metallic deposits consist mainly of bisulphide 

 of iron. The ore-bodies in the Canadian deposits are not so large. 

 From the cupreous pyrrhotite of Sudbury, rich though it be, com- 

 pared with the llio Tinto ore, the copper cannot be so cheaply ex- 

 tracted by the wet method, and the ore is of no avail as a source 

 of sulphur. Isickel is everywhere present in the cupreous pyrrhotite 



