THE COMSTOCK LODE. 51 



Waters above the 800-foot level are usually about 70° F,, whicli is also 

 the average heat of the rocky material of the vein. In the 1,040-foot level of 

 the Crown Point, and the lowest drifts from the Empire-Imperial, waters, 

 apparently rising from below, are found of a temperature of 102° F. 



The reader is referred to Atlas-Plate 6, for the arrangement of bonanzas. 

 This Plate, on a" scale of 200 feet to the inch, is a longitudinal elevation of mine- 

 works, and is tinted with purple to indicate the silver bodies. In the southern 

 part are the group of small ore-bodies in the single vein which traverses the 

 Uncle Sam, Overman, and the Segregated Belcher. In the western vein first 

 occurs the Belcher bonanza, of irregular, rounded outline ; next north, after a 

 barren interval, is the Crown Point west bonanza; succeeded again on the north 

 by the oblique spur representing the west vein in the Gold Hill mines. In 

 the east vein is the Crown Point bonanza, lying east of, and below the former. 

 This is a wide-spread deposit, clouded irregularly through the region within 

 the dotted line upon the Plate. After continuing down vertically to the 800- 

 foot level, it pitches thence northward, and expands rapidly in the Yellow 

 Jacket. In cross-section the ore of this bonanza shows a tendency to split into 

 parallel zones in the vein, ending upward, like wedges, in the quartz. 



In the great Gold Hill bonanza the mode of occurrence can be better 

 understood by a glance at Atlas-Plate 6 than by a lengthy description. The 

 quartz in the ore-bearing parts of the veins does not in any particular differ 

 from that in the barren portions. It is usually either reduced to blocks which 

 are crushed roughly together, or else shattered to a fine sugary state. There 

 are portions, as on the 700-foot level of the Yellow Jacket and Kentuck, 

 where it is a fine powder. So little compact, rocky quartz is there, that the 

 ore has been wholly removed \\dthout blasting. Commingled with this sugary 

 quartz are small, angular bits of propylite, and more or less clay infiltrations. 

 The bonanzas, as defined, give, in one sense, an erroneous impression, their 

 boundaries only representing the limits of the pay ore, on a grade rarely less 

 than $20 per ton. Throughout the uncolored parts of the Plate, the quartz has 

 only a small tenure of ore. The minerahzatiou and probable origin of these 

 bonanzas will be discussed at the close of this chapter. The Gold Hill bonanza 

 descended fi'om 250 to 550 feet, and although explorations have been pushed 

 500 feet further, the quartz is barren. In the Empire-Imperial lowest drift a 



