Ries — Geology of Urange County. 



44!) 



The wall rock is feldspathic and lias no hornblende, as indicated by the light 

 color which it has in the figure. 



From the Sterling mine the basic gneiss continues northeastward towards 

 the Augusta mine which is also on the property of the Sterling lion and 

 Railway Co. The strike of the gneiss at this mine is X. 4<»^' E. and the dip 

 50° E. The rock is made up of alternating bands of feldspar and hornblende 

 and the ore seems to favor the latter, dipping with the rocks. According to 

 the sections drawn from a survey made several years ago, the ore-body is long 

 and flat. There is a notable fault exposed in the hanging wall at the 

 entrance to the. mine. The layers of the gneiss have been drawn down by 



N.W 



100* 



S.L. 



Hanqinc 

 Wall 



Foot wall 



Figurk 15. l>iagra.nmat,c view of Clark mine, at Sterling; showing swelling and pinching ..f the 

 ore-bed. The section is N. W. and S. E. C is a vein of feldspar and hornblende, one foot thick 

 winch is pinched out. B is a N. E. and S. W. section of foot- wall at A 



the shearing action of the faulting. The foot-wall of the Augusta mine 

 contains much granular dark green pyroxene. There are many coarsel) 

 crystalline veins of quartz and feldspar which cut the gneiss in the walls 

 of the Augusta mine. They not uncommonly cut directly across the strike 

 and are often branched. 



The Mountain mine is about three-quarters of a mile north of the fore- 

 going, and consists of several long narrow parallel beds. At the Scott mine, 

 the gneiss is more acid and contains little or no hornblende, not even in 

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