188 SOUTHWESTERN NEVADA AND EASTERN CALIFORNIA. 
OLD CAMP. 
The almost deserted village of Old Camp, near Gold Mountain, 
is situated 30 miles west of south of Golclfield and 20 miles southeast 
of Lida. Abandoned mines and prospects are numerous in the vicin- 
ity and a number of prospects are being developed 2 or 3 miles south 
of the village. 
The Central mine, which supplied the ore used in the mill at Old 
Camp, may be taken as a type of ore deposits in the granite of this 
region. This mine is situated on the side of a dee}) gulch H miles 
north of east of the mill. Five tunnels, with an average length of 
300 feet, pierce the granite and all are situated on a single vein or 
system of connecting veins. The feldspars of the granite within 20 
feet of the vein are considerably kaolinized and the biotite is bleached 
or altered to a sericitic mineral. The quartz vein, or rather zone, 
within which the numerous connecting quartz veinlets and stringers 
occur, is from \\ to 6 feet wide, the proportional amount of quartz 
increasing with the narrowing of the zone. The ordinary veinlets 
;irc from ii to 5 inches wide. The zone also contains many ellipsoidal 
and globular areas of quartz which, at leasl in the plane of observa- 
tion, are independent masses. The quartz zone in some places changes 
its direction 90 c within 100 feet. While minor postmineral faults 
are common, the displacement ranging from 6 inches to 7 feet, the 
major changes in strike and dip are evidently parts of the original 
structure. 
The quartz i- white and translucent or slightly smoky, with a 
strong vitreous luster. Vugs with inch-long crystals are rather 
rare. Tn places the clear quartz seems to grade into a gray chalce- 
donic form, the deposition of which by ordinary waters can scarcely 
be doubted. Esolated crystals of pyrite, with very rare crystals of 
chalcopyrite and galena, are embedded in the quartz, while the former 
abundance of pyrite in particular is shown by numerous iron-stained 
cavities of cubical form. Both hematite and limonite occur in the 
porous quartz, and where these are abundant gold values rise. An 
occasional malachite -tain and a cerussite coating are also present. 
Dendrites of manganese dioxide occur in the granite, and are probably 
derived from the alteration of the granite rather than from a de- 
composing gangue mineral. Horn silver is reported to be present in 
small amount-, but was not seen. The ore is free-milling, the arras- 
tres, now abandoned, having saved about 75 per cent of the assay 
value. Films of a bluish-white chalcedony were noted at a number of 
places. Some of it was deposited prior to the oxidation of the pyrite 
and some was deposited after partial or complete oxidation. 
While the quartz is rather similar to the quartz of pegmatitic 
origin in the district, and the form of the ore deposit rather suggests 
that of a pegmatitic dike, the apparent gradation into chalcedony indi- 
