THE COMSTOCK LODE. 63 



and resembles the sugary variety far more than that of the Virginia vein, which 

 it touches. The latter mass is entirely barren, and possesses a fissile, almost 

 schistose structure. Little or no silver occurred in it, and its barrenness was 

 only occasionally varied by accidental specimens of gold. 



Upon Atlas-Plate 10 is a cross section through the Mexican mine, on the 

 plane of that company's shaft. The west wall here, of propylite, descends at 

 an average eastern dip of 47°; the Virginia quartz sheet, 50 feet thick, follows 

 it down to the seventh level, from thence narrowing to six feet on the tenth 

 station. As usual, the east fissure presents toward the vein a conchoidal 

 curve, joining the west quartz-body on the eighth station, 598 feet below the 

 datum-point. In cross section the quartz which follows the east wall is of 

 crescent shape, 40 feet wide on the fourth station, tapering to a mere blade at 

 the surface and a narrow edge on the seventh station. This body was charged 

 with the celebrated Ophir-Mexican bonanza. Eighty feet west, and lying 

 quite concentric with this, is a second thin sheet of quartz, curving down and 

 terminating on the west wall, a little above the seventh station. The main 

 east vein was of the typical ore-channel quartz, the thin middle sheet red and 

 blocky; while the heavy Virginia body, lining the west wall, was of fissile gray 

 blocks. 



Fig. 1, Atlas-Plate 12, shows the Ophir-Mexican bonanzas. In the upper 

 and north portion it will be seen that a nearly circular body lay concentric and 

 to the west of the main deposit of ore, overlapping it a little toward the north. 

 This western body, occupying the thin seam seen in the cross section, 

 extended 300 feet from north to south, and 250 feet in depth. The outlines 

 of the main eastern bonanza are very curious. From a width of 500 feet on 

 the surface, it descended with a general triangular outline to 675 feet in depth, 

 the northern boundary being more defined than the southern; the latter line 

 recurves toward the center of the bonanza. Near the lower extremity a bar- 

 ren portion occupied the middle of the deposit, extending from the Latrobe 

 adit down to 30 feet below the eighth station. The bonanza gave out at a 

 point indicated upon the cross section, and explorations were carried to a con- 

 siderable distance below without resulting in any favorable developments. 

 The company are now engaged in sinking a new shaft, several hundred feet to 

 the east of their old works, and will soon attack the lode by very deep levels. 



