TONOPAH EXTENSION MINE. 



183 



following in general the old hanging wall. Along this opening waters have cir- 

 culated and deposited jaspery quartz, cementing the broken fragments of the old 

 vein. On the 244-foot level the thickness of the jaspery subsequent quartz is about 

 li feet, while that of the typical antecedent quartz is about 3 feet. At the place 

 where the sketch (tig. 69) was made, the lower part has a value of about $600, while 

 the jaspery quartz has values of from $30 to $35. Moreover, it is probable that 

 these last-named values are in large part derived from included fragments of the 

 true vein, and also from the ruby silver which is sometimes found in cracks in the 

 jaspery quartz as well as in the true vein, this ruby silver being a secondary, mineral 

 derived from the primary ore. 



The general character of this subsequent vein filling renders it highly probable 

 that this vein is of the same nature and period as the veins in the Tonopah 

 rhyolite-dacite. While the main vein was formed after the eruption of the earlier 



O Midway shaft 



North Star shaft 



5 t? 

 j<* North Star vein [projected) 



Wl 13 ' * Montana Tonopah shaft 



^TONOPAH 

 Extension shall 



Mac Namara shaft 



TONOPAH MINING CO 



Main shaft 



Mizpah vein 



J * 



V 



Belmont vein 



West End shaft 



Valley View shaft 



Scale 

 500 



Fni. 70. Map showing principal earlier andesite veins now developed undergound, within the main productive area: 

 shown on the horizontal plane of the Mizpah 500-foot level. 



andesite, the subsequent tilling took place after the eruption of the rhyolite-dacite. 

 This main vein in the Tonopah Extension is probably identical with one of the 

 veins in the Mizpah or the Montana Tonopah. Very possibly it is the same as the 

 Montana vein, but this can not be definitely proved as yet. 



VEINS IN THE TONOPAH RHYOLITE-DACITE. 



The above conclusions as to subsequent filling are strengthened by certain 

 other occurrences in this same mine. On the 385-foot level a south drift from 

 the shaft cut the upper contact of a flat- lying north -dipping body of Tonopah 

 rhyolite-dacite. In this last-named rock, near the contact with the earlier andesite, 

 there is a great deal of silicification, amounting often to the formation of bodies 

 of pure jaspery quartz, of very irregular size and extent, and practically barren 



