220 



KEMP'S ORE DEPOSITS. 



lead-silver mines near Wickes have been referred to. (Example 

 33.) Red Mountain lies at the head of a valley like Wickes and 

 contains many narrow argentiferous veins. A concentrator was 

 at work on them in 1892. 1 



2.10.09. Silver Bow County. The copper mines and the gen- 

 eral geology of the Butte City region were referred to under 

 "Copper" (Example 17). In the basic granite, and north of the 

 copper zone, is a belt carrying sulphides of silver, lead, zinc, and 

 iron in a siliceous gangue, but abundantly associated with manga- 

 nese compounds of various sorts, especially rhodochrosite. 



No manganese is known in the copper belt, nor any copper in 

 the silver belt most striking phenomena in veins in the same wall 





fllilr 



12845 6 780 



FIG. 55. Cross section of vein at the Alice mine, Butte, Mont. The width 

 of vein is 40 feet. After W. P. Blake, M. E., XVI. , p. 72. 



1. Granite country. 2. Softened granite with small veins. 3. Clay wall with decom- 

 posed granite. 4. Quartz, broken and seamed. 5. Clay and decomposed granite. 6. Quartz 

 and manganese spar " curly ore." 7. Quartz and ore "hard vein." 8. Soft granite 

 with veinlets. 9. Dark-colored, hard granite of the hanging-wall country. 



rock. The line of outcrop has a crescentic sweep, and it was 

 therefore called by J. E. Clayton the Rainbow Lode. It includes 

 from west to northeast six claims, all but two of which are con- 

 trolled by the Alice Company. There are as many as four dis- 

 tinct veins present in the Magna Charta. All the mines show 

 that the ore and gangue have replaced the granite along a shat- 

 tered strip, for cross sections exhibit alternations of quartz with 

 ore, rhodochrosite, crushed wall rock, residual clay, occasional 

 horses of granite, etc. In the more siliceous granite west of the 

 butte is another silver belt with the same ores as in the Rainbow 



1 S. F. Emmons, Tenth Census, Vol. XIII., p. 97. J. S. Newberry, 

 " On R. d Mountain," Annals N. Y. Acad. Sci., III., p. 251. 



