OCCURRENCE OE THE ARGENTlTE 



97 



fact that the average specific gravity of three samples was found to be 

 6.55 as compared with 7.28 for the pure argentite. Quartz is sometimes 

 observable with the naked eye, and, as was mentioned above, proustite can 

 often, though not always, be seen on the argentite specimens. 



The average of two analyses of the argentite made by Mr R. B. Dennis 

 is as follows : 



Ag 83.57 



S 12. 6G 



Insoluble 3.62 



99.85 



The analysis was recalculated with the insoluble matter left out, with 



the following results : 



Found 



Ag 86.71 



S 13.13 



99.84 



Tlieoretical 

 87.1 

 12.9 



100.0 



The lower specific gravity (6.55) mentioned above conforms in general 

 to the amoimt of insoluble matter in the original analysis and probably is 

 due to the finely disseminated quartz. 



Paeagenesis of the Ores 



Owing to the limited nimiber of specimens which could be studied and 

 the fact that the author has never visited the mine, it does not seem war- 

 ranted to enter into a very extended discussion concerning the order of 

 deposition of the various ores mentioned above. One vein section was 

 observed which was about 14 inches wide and consisted entirely of an 

 irregular mixture of coarsely granular galena and sphalerite. ISTo other 

 conclusion seems justified but that both minerals were deposited at the 

 same time. Another section described above under the occurrence of 

 proustite shows the symmetrically banded or ribboned structure called 

 crustification by Posephny, which is considered as showing simple fissure 

 filling. This specimen contained the same irregular mixture of galena 

 and sphalerite on each side, followed by siderite, likewise symmetrical, 

 while the center was filled with the drusy mixture of proustite and quartz. 

 In still another section the same order is followed, except that argentite is 

 substituted for proustite. According to this arrangement, the galena and 

 sphalerite Avere deposited at the same time, followed by siderite, while the 



