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The following sulphides have been recognized in veins at 

 Porcupine : iron pyrites, copper pyrites, pyrrhotite, arsenical 

 pyrites, galena and zinc blende. Of these the most abundant 

 is iron pyrites, which occurs in some quantity in all the 

 gold-bearing veins. Copper pyrites, galena and zinc blende, 

 although also widely distributed, occur in minor quantity. 

 Pyrrhotite is the chief sulphide in the veins which are being 

 developed in No. 4 shaft of the Dome Extension. 



Only one telluride has been recognized, occurring in the 

 quartz-carbonate deposit at the Powell claim, M.E. 20, in 

 Deloro township. A chemical analysis of the mineral gave 

 the following results, silver 61.88 per cent, gold 0.10 per 

 cent., with strong reactions for tellurium, indicating the 

 mineral hessite. Native gold occurs as a later constituent 

 in minute seams in the hessite. 



In support of the theory of the relation of the quartz 

 veins of Porcupine to granite intrusions, may be mentioned 

 the following: 



1. The irregular occurrence of the quartz in many of the 

 deposits, in lenticular masses, resembling pegmatite dikes. 



2. The occurrence of feldspar, scheelite, and tourmaline 

 in the quartz in several deposits. 



3. The great pressure at which the quartz has been 

 deposited, indicated by the presence of liquid inclusions and 

 gas bubbles. These are frequently seen in quartz in 

 granites. 



4. The frozen contacts of quartz and enclosing country 

 rock. The free walls seen at some properties indicate a 

 secondary movement in the quartz, since these walls are 

 slickensided. Where free walls exist they may be either 

 the hanging or foot wall, while the other wall is indistinct — 

 grading into the country rock. 



5. The occurrence of narrow felsitic dikes, frequently 

 cut by minute veinlets of quartz, which represent the final 

 solidification of the felsitic magma, and which frequently 

 carry gold values as on Night Hawk lake. 



Character of the Gold-Bearing Deposits. 



The occurrence of gold at Porcupine is associated with 

 the quartz solutions which circulated through the fissures in 

 the Keewatin and Temiskaming series. The irregular 

 Assuring has produced a great variety of cmartz structures, 



