SILVER PEAK RANGE, MONTEZUMA DISTRICT. 
vertical bedding planes southwest of Alkali Spring. Small faults 
usually reverse, are common in the Cambrian rocks, while zone- of 
brecciation in the limestone indicate that differential movement has 
occurred at many places. The Siebert lake beds are approximately 
horizontal, although flexures and normal faults occur. The normal 
north-south fault west of Montezuma Peak has a throw probably 
amounting to several thousand feet. The uplift of this range since 
Miocene time has been great, since the Siebert lake beds, once be- 
neath a lake, have been elevated and eroded into mountains. 
ECONOMIC GEOLOGY. 
Two mining camps, Montezuma and Lida, are located in this spur 
of the Silver Peak Range. 
MONTEZUMA DISTRICT. 
The Montezuma mining district was organized in 1867, and soon 
afterwards several mines were opened in the country west of Monte- 
zuma Peak. In 1886 a mill was erected in the gulch to the north- 
vest of the mountain. Active work ceased in 1887, but at present 
number of prospectors are reopening old i:>roperties and locating 
|iew claims. The district product, estimated at $500,000, was 
reighted in wagons to Belmont, 65 miles away. At present only a 
ew shallow prospect holes and the dumps of the old mines are ac- 
essible for examination. The mineralized area lies to the west of 
ontezuma Peak, in Cambrian rocks. 
In the old mines the chief gangue is quartz, with rarely a little 
alcite and kaolinitic material. Vugs filled with quartz crystals 
>ccur in the quartz. The ores at the surface are cerussite, malachite, 
zurite, manganese dioxide, and limonite, and associated with these 
ncl replacing them in depth are galena, chalcocite, and pyrite. The 
allies are largely in silver, the gold values being uniformly low. 
hlorobromides of silver are reported, but were not seem 
A prospect hole exposes a quartz vein having white quartz-mon- 
onite porphyry as the hanging wall and limestone as the foot wall. 
halcopyrite is the original sulphide, and malachite with less limon- 
e, azurite, and a little native copper are the secondary ores. The 
ative copper forms thin sheets in cracks and small nodules in the 
ein. Malachite partially replacing limestone was noted at a num- 
er of other places. 
At Montezuma copper and lead sulphides with quartz fill open fis 
res in limestone. Some, probably all, of the deposition followed 
e pre-Tertiary dike injection. Later the veins were crushed, and 
rface waters altered the sulphides to carbonates, oxides, native 
etals, and probably haloid salts. This chemical breakdown of the 
lphides continues to the present day, as is shown by the fact that 
