306 



GEOLOGY OF THE EUEEKA DISTRICT. 



secondary fissure may he considered as an oifshoot from the more per- 

 sistent and profound Ruby Hill fault. Where the quartzite and limestone 

 show a tendency to curve to the south and southwest, following around the 

 spur of the mountain, the secondary fissure abandons the contact plane and 

 with a northwest course enters the limestone, leaving a block of the latter 

 rock between it and the quartzite. 



^Phoenix Af /he 



Quartzite CrusJied XLmes'tone ^/ud& 

 JLvimstone 



Rl^oUtc 



Fig. 6.— Cross-section in Phoenix mine. 



Within the wedge-shaped limestone body included between the Ruby 

 Hill fissure and the secondary fissure have been found all the deposits of 

 ore which were of sufficient value to repay extraction. Up to the time of 

 the present investigation all exploitations by crosscuts from the main levels 



