VALLEY VIEW VEIN SYSTEM. 129 



STRENGTH AND EXTENT OF THE BURRO VEINS. 



Of the three Burro veins, that next the Mizpah, No. 1, is the strongest. No. 2 

 is next, and No. 3, the farthest away, the weakest; thus an evident dependence 

 on the main vein is shown. Moreover, No. 1 is strongest as it approaches its 

 junction with the Mizpah. Here it is at the outcrop composed of solid quartz 4 feet 

 wide, and appears to be as important as the Mizpah itself. To the west, however, 

 the quantity of quartz in the vein zone decreases till the vein is difficult to follow, 

 and very likely actually dies out. Vein No. 2 is not regularly mineralized and 

 has not the characteristics of a strong fracture zone. While in general it grows 

 stronger on approaching the Mizpah, the only place from which high-class ore 

 has been taken is several hundred feet west of its junction, where the volume 

 of quartz in the vein increases. No. 3 follows a definite fracture zone in the 

 andesite and ordinarily has very good walls. In this zone the quartz is mostly 

 in stringers, irregular and bunchy. High-grade ore was taken out only from 

 one small portion of the outcropping vein, that being opposite the productive 

 portion of No. 2. The relation of good walls to a strong vein is continually 

 shown. Good walls denote a strong fracture zone, which is a good channel for 

 mineralizing waters. 



These veins have not been found to continue downward in general with the 

 same strength that they show on outcrop, and on the 300-foot level of the mine 

 they are represented only by weak silicifications or quartz seams, and not all of 

 them are with certainty identifiable. 



VALLEY VIEW VEIN SYSTEM. 

 THE VALLEY VIEW VEINS ON MIZPAH HILL. 



The Valley View vein outcrops, in its strongest portion, about 1,000 feet 

 south of the Mizpah vein. Its surface exposures are stronger and more compli- 

 cated than those of the Mizpah system, showing a number of veins which are 

 of various sizes, many of them being several feet thick. These are connected 

 by branches, so that the whole is interlaced. The general course is a little north 

 of east, practically parallel to the Mizpah vein, and the diiferent veins show a 

 tendency to fan out or diverge toward the west, as the Mizpah vein system does 

 to a more marked degree. The dip of the veins at the surface is nearly 

 perpendicular, some of them dipping north and some south, at angles usually 

 approaching 90. 



CROSS VEINS AND ALLIED PHENOMENA. 



Cross veins of considerable strength also occur, both on the east and on the 

 west side of the main outcrop, nearly at right angles to the main course. These 

 cross veins cut off the veins following the main course, though all are of the 



16843 No. 4205 9 



