MONTANA TONOPAH MINE. 



169 



VEIN ON THE 392-FOOT LEVEL. 



The nature ana relations of the Montana Tonopah veins are best seen from 

 figures. Fig. 58 shows the upper or 392-foot level, and the plan of the vein 

 first encountered in the shaft at that level. The vein is about 3 feet thick, of 

 the normal Tonopah type, such as has resulted from a silieification and minerali- 

 zation of the rock along a zone of ^___ 



close-set fractures; the values in it are 

 moderate. It is sharply cut off on the 

 east by the Mizpah fault. Near the 

 shaft it is cut by a number of small 

 northeast faults, generally steep and 

 dipping in both directions. These faults 

 nearly always have brought about an 

 upthrow on the northwest side, so that 

 in horizontal plan the vein is offset to the 

 southwest on the southeast side. These 

 faults are both normal and reversed 

 (fig. 59). The vein dips northwest at 

 an average angle of 45- or 50. 



This level, continued as a cross- 

 cut about 150 feet to the northeast, 

 cuts another vein, supposed to be the 

 Macdonald vein of the lower levels. 

 This vein strikes northeast and dips northwest at an angle of 40; it is from '2 

 to 4 feet thick and contains some good ore. Two portions of it, separated by 

 a northeasterly striking, southeast dipping (60) fault, are successively cut in the 

 drift. On account of this faulting the vein has not been much explored. 



Shaft BRANCH VEIN ON THE 460-FOOT LEVEL. 



1 



At 440 feet the shaft cuts a 

 minor vein below the one iust 

 described (fig. 60). This vein is 

 about 4 inches thick at the shaft 

 and was followed a short distance 

 northeast along its strike. At a distance of about 25 feet it was represented only by 

 stringers 2 inches or less thick, and was not farther drifted upon. To the southwest 

 of the shaft, what is probably the same vein was followed a longer distance, 

 becoming stronger and being from 8 to 18 inches thick. The ore in this part of 

 the vein is often of high grade, consisting of black and white quartz, crustified or 



FIG. 58. Horizontal plan of faults and vein on the 392-foot 

 level of the Montana Tonopah. 



zo feet 



Flo. 69. Vertical section along north drift. 392-foot level, Montana 

 Tonopah. 



