218 GEOLOGY OF THE COMSTOCK LODE. 



The quantity of i)yrite corresponds fairly well with the deficiency of iron 

 in the clays. Taking into consideration that these clays must have con- 

 tained chlorite corresponding to about 18 per cent, of augite, it appears 

 from the water contents that those from the Chollar and the Hale <& Nor- 

 cross can have included little or no kaolin. Those from the Yellow Jacket 

 and the Savage, on the other hand, may have contained both chlorite and 

 kaolin, but the latter only to the extent of a few per cent. 



Kaolinization not prevalent at Washoe. Thc Weight of OvidenCe is thuS reaSOUably 



strong that in the regions thus far exploited on and near the Comstock, 

 kaolinization, if it has taken place at all, has occurred only to a very trifling 

 extent, and that the degeneration of the feldspars results almost wholly in a 

 mixture of silica, calcite, and unrecognizable minerals, earthy in texture, in 

 part nearly opaque, and of a light color. 



Occurrence of ore and the accompanying rocks. As may be SeCU frOm the mapS aud 



sections, the Comstock Lode is several miles long, and is found in contact 

 with various rocks. The fissure is not simple, but ramified, and might have 

 been represented as still more complex, for the quartz veins struck by the 

 McKibben Tunnel in Spanish Ravine, and by the Peytona and other work- 

 ings on Cedar Hill, are unquestionably either stringers joining the Lode at 

 unknown points, or subsidiary parallel veins due to the same chain of dy- 

 namical and chemical causes as the Comstock. It appears from the longi- 

 tudinal vertical projection that but a small fraction of the fissure has been 

 filled with ore. This statement, however, requires explanation and qualifi- 

 cation. Nearly all the vast mass of quartz on the Comstock contains con- 

 siderable quantities of silver and gold, but none, of course, is extracted 

 which will not pay for working. While auriferous gravels may yield a 

 handsome profit when they contain considerably less than ten cents per ton, 

 and gold quartz may sometimes pay which contains two or three dollars, 

 Comstock ores carrying less than about twenty dollars can usually be 

 extracted only at a loss. Geologically the Comstock must be considered 

 as filled with metalliferous gangue, enriched at numerous spots, which are 

 known by the Spanish mining term "bonanzas." 



Vastly the most productive area has been that portion of the main 

 Lode between the Overman and the south end of the Sierra Nevada mine. 



