202 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
rich stringers, although very irregular in detail, are remarkably per- 
sistent along the hanging-wall side of the main lode. They possess, 
moreover, a regular internal structure. Next their walls there is usu- 
ally a thin layer of fluorite. Then follows a narrow band, from one- 
sixteenth to one-eighth of an inch in width, of rosin-yellow sphalerite 
and galena, with a few minute specks of chalcopyrite. The medial 
portion of the stringer is occupied by white quartz carrying a little 
sericite and calcite.. The gold occurs chiefly free in this white quartz, 
especially close to the dark ore lines near the walls of the stringer. 
It is firmly embedded in the quartz and is often distinctly visible, 
although not occurring in large masses. 
When the ore is crushed and panned, the concentrates contain 
abundant free gold in irregular hackly particles, averaging about 
0.25 mm. in diameter. Microscopic examination shows that the vast 
majority of these gold particles have the characteristics of original 
gold that has been embedded in vein quartz. A very few small, rod- 
like particles suggest a possible derivation from a telluride of gold. 
Chemical tests reveal the presence of a very small amount of some 
telluride in the ore, but it has not been detected by the eye and is 
not present in sufficient amount to determine its mineral species. 
Microscopic and chemical investigation shows that the value of the 
ore is chiefly in free gold and not in telluride of gold. 
The quartz in portions of the Camp Bird lode is often very glassy 
in appearance and shows little trace of mineralization, even when 
carrying some $20 per ton. Ore below $8 or $10 is not removed. The 
average value of all the material removed from drifts and stopes on 
the lode is probably not far from $40 per ton. The average on good 
stopes, however, may be three or four times this. According to a 
statement by Mr. J. W. Benson, manager of the Camp Bird mines, the 
material removed in merely running the main drift, waste included, 
ran in places about $1,600 per linear foot. Much of the vein quartz 
on the upper level (300 feet above main adit) is shattered and stained 
with black oxide of manganese. The shattering of the brittle quartz 
does not appear, however, to be associated with any very pronounced 
post-mineral movement, nor has it any known effect on the tenor of 
the ore. A little rhodochrosite and considerable calcite occur in the 
lode, the latter often filling vugs or comb structure in the quartz. A 
soft, white, putty-like substance, which proves to be chiefly kaolin, is 
also common in the quartzose portions of the lode. 
Not enough development has yet been reached to determine the 
shape of the pay shoots. The ore body on the west drift of the main 
level is about 1,200 feet in length. Other pay shoots occur along the 
vein, separated by pinches. They are said to be increasing in length 
as they are followed down, The ore bodies east of the crosscut are 
generally wider, but of lower grade than the large one west of it. 
About 1,700 feet west of the crosscut tunnel on the main level the 
