294 8B. Silliman on the Mining Districts of Arizona. 
This is true of by far the greater number of all the outcrop- 
pings in the District. There is another set of lodes, however, 
much less numerous than the first, whose general direction is 
northwest and southeast, or more exactly 20° W.: these 
lodes, if prolonged, must obviously intersect, at certain points, 
some of the east-and-west lodes. They differ not only in their 
course and direction, but essentially in their mineralogical con- 
stitution. The first series, the east-and-west, are quartz Jodes, 
characterized by the presence of feldspar and fluor spar as the 
peculiar associate minerals; showing also rather rarely at sur- 
face metallic sulphurets and free gold. The second set of lodes 
may be called calcareous, being composed to a great extent of 
magnesian carbonate of lime or dolomite, flanked in some cases 
by quartz linings with polished walls, and as a general rule quite 
barren and unpromising in their outcrop. The Virginia, Olive 
Oatman, and Buffalo are conspicuous examples of the calca- 
reous lodes. A third class of lodes is observed in the San 
Francisco District whose main direction is northeast and south- 
west. This class is very small, not including more than three 
or four, namely, the Pride of Mexico, Triumvirate, Wright, and 
Resources in timber and water,—San Francisco District, like all 
the neighboring regions of the Colorado, is entirely destitute of 
timber, and at present is very imperfectly supplied with water. 
Timber is said, however, to exist in considerable abundance,— 
cotton-wood, cedar, pitch-pine, and nut-pine,—-on or near the 
banks of the Colorado, within 100 miles of Silver Creek; at 
points from which it can be brought at a moderate cost for the 
supply of fuel and mining timber to meet the future demands of 
this district. ‘ : 
When we remember the experience in Nevada, especially the 
dearth of water on Mt. Davidson, in the early history of mining 
on the Comstock lode in Virginia City, and its present compara- 
tive abundance there as the result of mining operations, we are 
encouraged to believe that a similar result may be expected 2 
San Francisco District, especially since the very limited explora~ 
tions which have been carried out here have resulted in the 
discovery of water even in the dries 
a single hour, convert the dry arroya into a broad and roaring 
water courses find an abundant supply of water at a few feet 
