170 SILVER LEAD DEPOSITS OF EUREKA, NEVADA. 



It has been stated before that the opportunities for the deposition of ore 

 have depended in a great measure upon the extent to which the limestone 

 has been crushed and thus prepared for its reception and deposition. It 

 cannot be said that such a shattering' of formations has not taken place to a 

 great extent on Prospect Mountain. It has, and its results are shown by 

 the numerous fissures and zones of pulverized rock which are encountered 

 in this region; nevertheless, the upheaval and faulting did not take place 

 under conditions that were in every way as favorable as those which resulted 

 in the present structure of Ruby Hill. The faults which brought about the 

 present arrangement of the formations in the latter locality were accom- 

 panied by the formation of a fault-fissure which acted as a channel through 

 which the metalliferous solutions entered the wedge-shaped mass of lime- 

 stone lying between this main fissure and the quartzite. Whatever other 

 part this quartzite may have played in the formation of the mineral zone of 

 Ruby Hill, it certainly had the effect of confining the ore-bearing solutions 

 to the crushed limestone bounded by the clay of the Ruby Hill fault. Had 

 these solutions entered a mass of limestone of unlimited extent, although 

 the amount of ore deposits might have been as great in the aggregate, it is 

 not likely that ore bodies of a size equal to that for which this mineral belt 

 has been noted would have been deposited. It cannot be denied that cer- 

 tain ore channels exist in Prospect Mountain, and that they are also con- 

 fined in some instances between belts of shale, or between walls of lime- 

 stone; yet, as far as present developments have shown, there has been no 

 such limitation of the ore to a well-defined region. 



Resources of Prospect Mountain. — These facts, however, need not prove a draw- 

 back to a careful exploration of the resources of Prospect Mountain. The 

 Ruby Hill deposits were worked to a large extent, when the cost of mining 

 and reducing ores was far greater than it is at present, in spite of which 

 they paid large profits; and a reduction in the cost of working-ores, coupled 

 with the increased facilities offered by the tunnels and more systematic 

 methods of mining, will compensate in a very great degree for any dif- 

 ference in the size of the ore bodies which may exist in the two regions. 



Relative richness of the deposits of Prospect Mountain and Ruby Hill. It is Said that tll6 



ore of Prospect Mountain, as a rule, is richer than that of Ruby Hill. This 



