302. B. Silliman on the Mining Districts of Arizona. 
interesting: the “pay streak” or productive ore ground is seen 
to be here about three feet wide in two nearly equal divisions, 
separated by about one foot of soft yellowish and reddish 
material, which prospects well for gold. This softer seam has 
come in on sinking and is not seen at all at surface. It is in- 
ereasing in width as the shaft descends and is easily worked by 
the pick alone. Its dip is such that it passes out of the shaft in 
twenty-seven feet, the shaft being eight feet wide. The hanging 
wall is perfectly definite and shows smooth “slickensides,” with 
a clay lining between them in places from three to four inches 
in thickness. ‘The upper-rock is a reddish feldspathic porphyry, 
with thread veins of quartz. The vein stuff shows very little 
sulphurets and the porphyry comes in between the walls. The 
quartzose ground increases as the shaft descends, until at its 
er. 
tanity of comparing the physical features of the Moss vein with 
the surface show upon the “Comstock lode” in Nevada, I was 
forcibly strack with the great resemblance of these portions of 
the Moss vein with that portion of the Comstock which is still 
seen at Gold Hill, south of Virginia City, where similar rich 
deposits of low grade gold in the quartz outcrop gave its name 
1863 by Mr. Chas. W. Strong, who is in an active 
exploration of this interesting letdlity en ape # ‘party of 
New York capitalists: 
