Jansome.] LODES OF SILVER LAKE BASIN. 147 
sistent lodes, which may be referred to as the Silver Lake and Titus- 
ville lodes. The general course of the fissures of this group is nearly 
northwest and southeast. The second group embraces a number of 
shorter lodes, having a general average course about N. 25° W., and 
lying between the two chief lodes of the first group. The members of 
the second group are locally spoken of as " north-and-south veins" — 
an obviously inaccurate expression. 
The general dip of all the productive lodes in the basin is northeast- 
erly, although some of them are nearly vertical and often dip locally 
to the southwest. Those of the first group frequently have a much 
flatter dip than those of the second group, and the ore is generally of 
lower grade and more irregular in its occurrence. Large bunches of 
ore are separated by relatively barren portions of the lode. As a rule 
the product is a lead-silver ore, consisting chiefly of galena accompa- 
nied by sphalerite, chalcopyrite, pyrite, and sometimes tetrahedrite. 
In some cases the silver maybe so low as to be subordinate in impor- 
tance to the lead. The lodes of the second group have a much steeper 
dip, the average being probably near 80°. Their ore bodies are usu- 
ally more regular and of higher grade. Galena is still the most promi- 
nent ore mineral, but chalcopyrite and pyrite are generally more 
abundant, and the ore may cany several ounces of gold per ton. 
These lodes have been best explored toward the north, where some of 
them form junctions with the Silver Lake lode. Several of them 
pinch and die out in a few small, irregular stringers before reaching 
this fissure. Others, such as the New York City and Royal veins, 
reach and connect with the master lode. The general relations of the 
lodes of the two groups can perhaps be best understood from fig. 2, 
page 51, which is a generalized and diagrammatic sketch of the plan 
)f the principal fissures exploited in the Silver Lake and Iowa mines, 
m the west side of Silver Lake. The Silver Lake lode is fully as long 
igain as shown. It has been exploited on the northwest through the 
)ld Nevada mine and is known to extend into the head of Blair Gulch. 
Toward the southeast it passes under the lake and is probably con- 
iinuous with the lode of the Royal Tiger mine. Just before cross- 
ng the southeast rim of the basin, the Tiger lode divides into two 
wanches, neither of which has been traced far beyond the point of 
livergence. A plat of the principal claims of Silver Lake Basin and 
.icinity is shown in PI. XIII. 
As the lodes of the second group approach the junction with the 
Silver Lake vein they become poor. Their courses are also deflected 
oward the west, as indicated in the sketch. The country rock in the 
/ near the junction is usually shattered and traversed by numerous 
juartz stringers. Some of these are irregular, but there is often 
loticeable a radiation of the stringers outward from the angle of junc- 
ion. In some instances a breccia has resulted, the fragments being 
jemented by quartz and themselves altered into aggregates of quartz, 
