92 



were ultimately filled with these minerals. Then there 

 was a slight disturbance of the veins, reopening the ore- 

 filled fissures and cracks, or facturing the material deposited 

 in them. 



In the interval, between the filling of the fissures and 

 cracks with cobalt-nickel ores and the fracturing of the 

 veins thus formed by a secondary disturbance, the char- 

 acter of the material carried by the circulating waters had 

 changed. Silver was then the characteristic metal in 

 solution and it was deposited, along with calcite, in the 



Polished surface of silver ore, slightly magnified, from La Rose 

 mine. Cobalt. The native silver, S, is the white material in 

 the illustration. The large black patches are calcite, the small 

 black spots niccolite, and the grey is smaltite. 



cracks and openings in the fractured veins. There may 

 have been some silver deposited in the earlier period of vein 

 filling and doubtless cobalt-nickel minerals were deposited 

 after the secondary disturbance, but the latter minerals 

 belong characteristically to the first generation and the 

 silver minerals to the second. 



Certain writers on the Cobalt ores have expressed the 

 opinion that the silver represents " secondary enrichment," 

 meaning that it has come from the decomposition of com- 



