404 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



the liill under the basalt. At the time of my visit it was inaccessible, but 

 I was assured by the watchman, an old miner, that a dike of the lava was 

 encountered and that at its contact with the inclosing rock cinnabar oc- 

 curred. Basalt does not elsewhere in this di.strict come in contact with 

 ore, but the Redington, Lake, Manhattan, and Reed mines and a number of 

 prospects showing cinnabar, as well as the mineral springs, are grouped 

 around the edges of the basalt area. Considering the occurrences near 

 Knoxville in the light of the facts developed near the ^Etna Springs and at 

 Sulphur Bank, there appears to me to be no doubt wliatever that all three 

 localities have been charged with cinnabar in the same maimer. 



No two mines on the quicksilver belt possess a stronger similarity than 

 the New Idria and the Redington. Each is close to the contact between a 

 very large metamorphic area and unaltered rocks ; each carried large quan- 

 tities of metacinnabarite ; eacli was very irregular in structure on the upper 

 levels and developed well defined fissures below, and there is no diff'erence 

 in the association of minerals in the two mines. At New Idria, however, 

 there are no direct means of determining the method of genesis. No sul- 

 phurous gases or hot water now enter the mines, and the nearest known 

 basaltic area is 10 miles away. At the Manzanita also no eruptive rocks 

 are found, though there is abundant evidence of the action of liot springs. 

 Th'Te is nothing whatever to justify tlie supposition that the deposits of 

 .NOV i.iria are due to different causes than those which led to the formation 

 of ores at Knoxville and other localities north of San Francisco. 



The New Almaden, Enriquita, and Guadalupe mines lie nearly in a 

 straight line, along which quicksilver has been found at numerous points. 

 No hot gases or water are found in the mines, but nearly parallel with them 

 and at an average distance of about a mile is a rhyolite dike, which has 

 been followed for several miles. This association of course suggests that 

 heated waters of the volcanic type must at some time have reached the sur- 

 face in the neighborhood, and probably along the line of the deposits. 



The relations described in the foregoing paragraphs appear sufficient to 

 establish the facts that no grounds exist for supposing the various cinnabar 

 deposits to have been formed by different methods and that a considerable 

 number of them are due to the action of hot sulphur springs. In the sue- 



