GENERAL CHARACTER OF THE ORE DEPOSITS. 
values largely silver. In quartzite and schist, in metamorphosed 
limestones composed of quartz, garnet, epidote. and calcite, and in 
limestone zones in which silification extended beyond the qua 
vein pyrite is the predominant sulphide, with gold values alone or 
in excess of silver. It is probable that the relative abundance and 
variety of sulphides were determined by the wall rock, the more 
siliceous rock tending to precipitate from the waters auriferous 
pyrite and the calcareous rock precipitating argentiferous galena 
and chalcopyrite. The secondary ores of this subdivision include 
malachite, azurite, ehrysocolla, native copper, brochantite, cerussite, 
emmonsite (or durdenite), native gold, and horn silver, while chloro- 
bromides of silver are reported. Chalcocite is probably of secondary 
origin. Two or more of these ores are associated with hematite and 
limonite or with a heavily stained jaspery quartz with conchoidal 
fracture. Gypsum, and at one place sulphur, are secondary gangues 
of less wide distribution. The secondary minerals replace the 
wall rock and in part fill open fissures. In many places cavities in 
the secondary ores are frosted by later quartz crystals. The Tokop 
veins belong to this subdivision and their similarity to veins 
in the granite of Old Camp and their reported extension into the 
granite beneath indicate that the quartz veins in the granite and 
limestone are contemporaneous in age and of like origin, a conclu- 
sion entirely in accord with the character of both the gangues and 
ores of types A 3 and B 1. The quartz veins in the granite (A 3) 
are not demonstrably of pegmatitic origin and yet their form, 
here lenslike, there sigmoid and independent of apparent fault- 
ing, is, in many instances, more closely allied to that of a 
pegmatite dike than to that of a water-deposited vein. In the 
Paleozoic rocks surrounding granite masses these quartz veins are 
fbundant, a fact exemplified by the clustering of mining camps 
round the post-Jurassic intrusive masses. At a distance from the 
[granite the veins decrease in number and in size, and finally the 
pame ores replacing the limestone occur without quartz, as ai 
Duprite. It is probable that the quartz veins in granite and limestone 
jvere deposited by heated waters, in part at least the magmatic 
vaters of the granite, but much more remotely connected with the 
nagma than those which formed the pegmatite dikes. The re- 
llemblance between the ores of these veins and those of the veins 
lilong contacts (B 3) is striking. The latter deposits may have been 
laid down by waters from portions of the granite deeply buried and 
Itill molten, or by waters from the white quartz-monzonite porphyry, 
In igneous rock probably genetically related to the granite. 
The Lida, Bare Mountain, and Oriental Wash deposits, and some 
if those of Chloride Cliff, Montezuma, Oak Spring, and Southern 
