98 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
shoots, with the intervening lower-grade quartz, are all stoped out in 
working and would not appear in an ordinary stope map. It is 
beyond question, however, that in this mine the best ore occurs in 
quartz which has been crushed by movements subsequent to its 
original deposition. The solid, unbroken, unstained quartz is invari- 
ably of somewhat lower grade. As in the Camp Bird, the auriferous 
ore is next the hanging wall, a silver-lead streak lying near the foot 
wall. 
From large, regular pay shoots, such as are found in the New York 
City, Camp Bird, and Tombo}^ lodes, all gradations may be found 
through smaller, more irregular ore bodies down to the occasional 
small i^ockets of rich ore encountered in some of the lodes of Deer 
Park and Maggie Gulch. 
The changes which take place in pay shoots with depth are exceed- 
ingly important in mining operations. Unlike the auriferous lodes of 
California, which rarely show any progressive or regular change in 
the character of their ores even to depths of 2,500 feet, the pay shoots 
of the Silverton quadrangle are less constant. It is a common belief 
among mining men of this region that lead ores do not go down to 
great, or even to moderate, depths. In part this opinion is plainly 
traceable to the experience gained in exploiting the stocks of the Red 
Mountain district, which will be described in subsequent pages; but 
it is pertinent here to see how far it is justified by the know T n facts in 
regard to the lodes. 
In the Aspen mine there are said to have been several veins near 
the surface which came together at moderate depth. Below a depth 
of 800 feet the galena, which was veiy abundant in the upper levels, 
is said by Mr. W. H. Thomas to have so diminished in amount as to 
make further work unprofitable. According to the same informant 
the ore of the Belcher mine, on Sultan Mountain, carried abundant 
galena of good grade in the upper workings, but this decreased in 
amount and value in the lower levels, while sphalerite grew more 
abundant. Actual verification of these statements by observation is 
not now practicable, but Mr. Thomas, who had been connected with 
both mines, was undoubtedly himself convinced of the truth of his 
statements. In the Royal, Stelzner, New York Cit} T , Iowa, and East 
Iowa lodes there is no present indication of an} T diminution of galena 
or of any other regular change in the ore with increasing depth. The 
ore of the New York City lode where cut by the Unity tunnel, about 
1,200 feet below the croppings, shows abundant galena, and is similar 
to the ore in the same vein on levels C and I, 400 and 700 feet, 
respectively, above the Unity ievel. If anything, it is of higher 
grade. The Buckeye lode (part of the Titusville lode) has not been 
exploited to great depth, but tetrahedrite was undoubtedly more 
abundant in the upper than in the lower tunnel. In the North Star 
mine, on Little Giant Peak, a change in the character of the ore is 
