264 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



same rocks are met in otlier mines and the gangiie minerals and the relations 

 of these substances to the vein rock are those most usual in California. 

 This fact is an important one, for it proves that deposits indistinguishable 

 from those found in the Redington, New Almaden, and other mines may be 

 formed] n the same manner as those at Sulphur Bank, by precipitation from 

 hot springs of volcanic origin. 



Partl}^, perhaps, on account of the degree to Avhich the hot water and 

 foul gases interfere with mining operations the pro.specting of this property 

 has been neglected, and tliere is an insufficient opportunity to study the 

 structural relations of the ore and the fissures. I can, however, see no 

 reason to suppose that the deposit is exhausted. A drift should be run 

 through the ground which shows solfataric action beneath the surface mine 

 at a depth of at least 200 feet, and from this gallery at least one cross-cut 

 should be driven, so that the hopeful ground would be completely inter- 

 sected in two directions. It would probably be found that these drifts 

 would meet one or more dikes of basalt, the direction of which would mark 

 the main fissure S3"stem ; but for some hundreds of feet from the surface the 

 structure and the disposition of ore are probably very irregular, and a sys- 

 tem of straight drifts and cross-cuts would be the only thorough method 

 of exploration. 



The abandoned mines on Mt. Konocti appear to have had an origin 

 entirely similar to that of the Sulphur Bank. Their chief interest is due to 

 the fact that they occur in andesitic lavas, thus adding to the list of differ- 

 ent rocks in which cinnabar in some quantity is found and increasing the 

 probability that all the cinnabar is derived from a single source. 



Little Sulphur Bank and Borax Lake A fcW llUUdred fcCt tO the CaSt of tlie mud 



flat of Borax Lake, and just at the edge of the obsidian area, is the so-called 

 Little Sulphur Bank. Here slight excavations only have been made. These 

 show a considerable quantity of impure sulphur, and I was positively in- 

 formed that traces of cinnabar had been found, though not enough to 

 encourage further exploration. No water flowed from this locality during 

 my visit, but the ground was moist and hot in spots. It is possible that 

 during some seasons hot water may still find its way to the surface and drain 

 into Borax Lake. Everything thus indicates that the locality is properly 



