94 



a comparatively shallow depth, the absence of the pre- 

 cious metal is to be accounted for by the fact that such 

 veins, or parts of veins, escaped fracturing during the 

 secondary disturbance, thus not affording openings for 

 deposition from the silver-bearing solutions. 



Frequently, below the rich silver-bearing parts of veins 

 well crystallized argentite and hair silver are found in 

 vugs. These minerals may represent secondarv deposition 



An underground view in La Rose mine, Cobalt, showing parallel 



veins. 



of a little of the silver that has been dissolved from the 

 upper part of the veins and carried downward. 



Characteristically, the native silver of the area is im- 

 pure, chiefly from the presence of antimony and mercury. 

 Samples of well crystallized silver and certain vcirilets of 

 the mineral that have been examined are free from these im- 

 purities. Such silver is probably of secondary origin. 



When native silver is precipitated by its solutions coming 

 in contact with cobalt-nickel minerals, compounds of nickel 



